LD/Genetic Conditons

Question 1

What condition should be suspected in a child with epilepsy and language regression occurring around age 6–7 years?

Options

A. Fragile X syndrome
B. Rett syndrome
C. Landau-Kleffner syndrome
D. ASD
E. Down syndrome

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Answer 1

✅ Correct answer: C. Landau-Kleffner syndrome

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🧠 Explanation

Landau-Kleffner syndrome = acquired epileptic aphasia.

Key features:

👉 Previously normal language development
👉 Sudden or gradual language regression
👉 Epileptiform EEG abnormalities
👉 Onset typically 3–7 years

⭐ High-yield facts
• Also called acquired epileptic aphasia
• EEG abnormalities during sleep
• May be mistaken for autism
• Requires urgent neurological input

⚠️ MRCPsych traps
• Confusing with ASD regression
• Choosing Rett due to regression

Question 2

✔ Apparently normal early development (first 6–18 months)
✔ Followed by developmental regression

Loss of previously acquired skills, especially:
• Loss of purposeful hand use + stereotyped hand movements
• Loss of spoken language
• Loss of social engagement

👉 This regression after normal infancy is the classic clue.

Answer 2

Rett Syndrome

Question 3

✔ Classic triad:
• Normal early development (first 6–18 months)
• Developmental regression
• Loss of purposeful hand use + stereotyped hand movements

✔ Additional highly specific features:
• Acquired microcephaly (decelerating head growth)
• Breathing abnormalities when awake
• Predominantly affects girls

Answer 3

Rett Syndrome

Question 4

Rett syndrome predominantly affects females because:

A. It is autosomal recessive
B. It is X-linked dominant and often lethal in males
C. It is mitochondrial
D. It is Y-linked
E. It requires hormonal activation at puberty

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Answer 4

✅ Correct answer: B. It is X-linked dominant and often lethal in males

Explanation:

✔ Males with MECP2 mutations often die before birth or in early infancy
✔ Females survive due to X-inactivation mosaicism

Question 5

Which feature most reliably distinguishes Rett syndrome from autism spectrum disorder?

A. Impaired social interaction
B. Language delay
C. Hand-wringing stereotypies with loss of purposeful hand use
D. Intellectual disability
E. Sensory sensitivities

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Answer 5

✅ Correct answer: C. Hand-wringing stereotypies with loss of purposeful hand use

Explanation:

Many features overlap with autism, but loss of purposeful hand skills with characteristic stereotypies is highly specific for Rett syndrome.

Question 6

A 5-year-old boy has developmental delay, large ears, macrocephaly, gaze avoidance, and repetitive hand flapping. What is the most likely diagnosis?

A. Autism Spectrum Disorder
B. Fragile X syndrome
C. Prader–Willi syndrome
D. Rett syndrome
E. Smith–Magenis syndrome

⸻

Answer 6

✅ Correct answer

B. Fragile X syndrome

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3️⃣ Clear, exam-focused explanation (why correct + why others wrong)

✅ Why B is correct (examiner logic)

The stem gives a classic Fragile X neurodevelopmental + physical phenotype:
• Male (X-linked condition → males more severely affected)
• Developmental delay / intellectual disability
• Macrocephaly
• Large ears (and often long/narrow face)
• Autistic-like features: gaze avoidance, repetitive behaviours, social anxiety

This is exactly how Paper B tests Fragile X:
➡️ “ASD-like behaviours + characteristic physical features + male” → Fragile X.

📘 ICD-11 / DSM-5 / NICE rules + what the exam is testing

This is DIAGNOSIS (syndrome recognition in Intellectual Disability).

ICD-11 / DSM-5 concept
• Intellectual developmental disorder/intellectual disability requires:
• deficits in intellectual functioning AND
• deficits in adaptive functioning
• onset during developmental period
• Many genetic syndromes present with “syndromic ID” + autistic traits.

NICE principles (ID + autism features)
• Consider genetic assessment when:
• intellectual disability + dysmorphic features
• developmental delay + physical phenotype
• ASD with global delay / unusual physical features
• Look beyond “ASD label” when syndromic clues present.

⸻

⭐ High-yield facts to memorise (5–7)
• Fragile X = most common inherited cause of intellectual disability
• X-linked → males more severely affected
• Physical: long face, large ears, macroorchidism (post-pubertal), macrocephaly
• Behaviour: ADHD/hyperactivity, gaze avoidance, social anxiety, ASD traits
• Cause: FMR1 CGG repeat expansion (X chromosome)
• Anticipation: worsens in successive generations
• Females may have milder symptoms due to X-inactivation

⸻

⚠️ Common MRCPsych exam traps
• Diagnosing ASD without considering syndromic causes
• Mixing Fragile X with Rett (both have autistic traits but different sex + course)
• Forgetting macroorchidism appears after puberty, not at age 5

Question 7

A 5-year-old boy has developmental delay, large ears, macrocephaly, gaze avoidance, and repetitive hand flapping. What is the most likely diagnosis?

A. Autism Spectrum Disorder
B. Fragile X syndrome
C. Prader–Willi syndrome
D. Rett syndrome
E. Smith–Magenis syndrome

Answer 7

✅ Correct answer

B. Fragile X syndrome

⸻

✅ Why B is correct (examiner logic)

The stem gives a classic Fragile X neurodevelopmental + physical phenotype:

X-linked → males more affected
Most common inherited ID
Anticipation phenomenon
Females milder due to X-inactivation

Large ears, long face, macrocephaly
Macroorchidism after puberty
Repetitive hand flapping
Hyperextensible joints, hypotonia, flat feet (pes platus)
High arched palate
Pectus excavatum
Mitral valve prolapse
Seizures in 10%

Developmental delay
Intellectual disability
ADHD and ASD features common
Social anxiety and gaze avoidance

This is exactly how Paper B tests Fragile X:
➡️ “ASD-like behaviours + characteristic physical features + male” → Fragile X.

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❌ Why the other options are wrong (high-yield distractor logic)

A. Autism Spectrum Disorder
• ASD explains:
• gaze avoidance
• repetitive behaviours
• BUT does not explain the syndromic physical features (macrocephaly + large ears) + global developmental delay pattern.
• Exam expects you to recognise “ASD phenotype + dysmorphism” → genetic syndrome.

Trap: “ASD is the diagnosis” — but they’re testing syndromic ASD.

⸻

C. Prader–Willi syndrome
Typical features:
• neonatal hypotonia + feeding difficulty → later hyperphagia/obesity
• short stature
• hypogonadism
• mild–moderate ID
Not a “macrocephaly + large ears + gaze avoidance” presentation.

⸻

D. Rett syndrome
• Almost exclusively females
• Normal early development → then regression (6–18 months)
• loss of purposeful hand use + hand-wringing stereotypies
• microcephaly (acquired) often later
Not male, not macrocephaly.

⸻

E. Smith–Magenis syndrome
• Distinct phenotype:
• sleep disturbance (inverted melatonin rhythm)
• self-injury, impulsivity
• coarse facial features, short stature
• Not the classic “large ears + macrocephaly + autism-like” Fragile X package.

⸻

4️⃣ 📘 ICD-11 / DSM-5 / NICE rules + what the exam is testing

This is DIAGNOSIS (syndrome recognition in Intellectual Disability).

ICD-11 / DSM-5 concept
• Intellectual developmental disorder/intellectual disability requires:
• deficits in intellectual functioning AND
• deficits in adaptive functioning
• onset during developmental period
• Many genetic syndromes present with “syndromic ID” + autistic traits.

NICE principles (ID + autism features)
• Consider genetic assessment when:
• intellectual disability + dysmorphic features
• developmental delay + physical phenotype
• ASD with global delay / unusual physical features
• Look beyond “ASD label” when syndromic clues present.

⸻

5️⃣ ⭐ High-yield facts to memorise (5–7)
• Fragile X = most common inherited cause of intellectual disability
• X-linked → males more severely affected
• Physical: long face, large ears, macroorchidism (post-pubertal), macrocephaly
• Behaviour: ADHD/hyperactivity, gaze avoidance, social anxiety, ASD traits
• Cause: FMR1 CGG repeat expansion (X chromosome)
• Anticipation: worsens in successive generations
• Females may have milder symptoms due to X-inactivation

⸻

6️⃣ ⚠️ Common MRCPsych exam traps
• Diagnosing ASD without considering syndromic causes
• Mixing Fragile X with Rett (both have autistic traits but different sex + course)
• Forgetting macroorchidism appears after puberty, not at age 5

Question 8

Symptoms vary in severity, with males often more affected than females.

Developmental/Cognitive: Mild to moderate intellectual disability, developmental delays (delayed speech/language), and short attention span.

Behavioral: ADHD-like behaviors (hyperactivity, impulsivity, restlessness), social anxiety, extreme shyness, and hand-biting or hand-flapping.

Physical Features: Long, narrow face, large ears, flexible fingers, flat feet, and, after puberty, large testicles.

Medical Complications: Potential for seizures, ear infections, and connective tissue issues like mitral valve prolapse.

Answer 8

Fragile X Syndrome

Question 9

A 5-year-old boy has developmental delay, large ears, macrocephaly, gaze avoidance, and repetitive hand flapping. What is the most likely diagnosis?

A. Autism Spectrum Disorder
B. Fragile X syndrome
C. Prader–Willi syndrome
D. Rett syndrome
E. Smith–Magenis syndrome

Answer 9

✅ Correct answer

B. Fragile X syndrome

⸻

The stem gives a classic Fragile X neurodevelopmental + physical phenotype:
• Male (X-linked condition → males more severely affected)
• Developmental delay / intellectual disability
• Macrocephaly
• Large ears (and often long/narrow face)
• Autistic-like features: gaze avoidance, repetitive behaviours, social anxiety

This is exactly how Paper B tests Fragile X:
➡️ “ASD-like behaviours + characteristic physical features + male” → Fragile X.

⸻

❌ Why the other options are wrong (high-yield distractor logic)

A. Autism Spectrum Disorder
• ASD explains:
• gaze avoidance
• repetitive behaviours
• BUT does not explain the syndromic physical features (macrocephaly + large ears) + global developmental delay pattern.
• Exam expects you to recognise “ASD phenotype + dysmorphism” → genetic syndrome.

Trap: “ASD is the diagnosis” — but they’re testing syndromic ASD.

⸻

C. Prader–Willi syndrome
Typical features:
• neonatal hypotonia + feeding difficulty → later hyperphagia/obesity
• short stature
• hypogonadism
• mild–moderate ID
Not a “macrocephaly + large ears + gaze avoidance” presentation.

⸻

D. Rett syndrome
• Almost exclusively females
• Normal early development → then regression (6–18 months)
• loss of purposeful hand use + hand-wringing stereotypies
• microcephaly (acquired) often later
Not male, not macrocephaly.

⸻

E. Smith–Magenis syndrome
• Distinct phenotype:
• sleep disturbance (inverted melatonin rhythm)
• self-injury, impulsivity
• coarse facial features, short stature
• Not the classic “large ears + macrocephaly + autism-like” Fragile X package.

⸻

📘 ICD-11 / DSM-5 / NICE rules + what the exam is testing

This is DIAGNOSIS (syndrome recognition in Intellectual Disability).

ICD-11 / DSM-5 concept
• Intellectual developmental disorder/intellectual disability requires:
• deficits in intellectual functioning AND
• deficits in adaptive functioning
• onset during developmental period
• Many genetic syndromes present with “syndromic ID” + autistic traits.

NICE principles (ID + autism features)
• Consider genetic assessment when:
• intellectual disability + dysmorphic features
• developmental delay + physical phenotype
• ASD with global delay / unusual physical features
• Look beyond “ASD label” when syndromic clues present.

⸻

⭐ High-yield facts to memorise (5–7)
• Fragile X = most common inherited cause of intellectual disability
• X-linked → males more severely affected
• Physical: long face, large ears, macroorchidism (post-pubertal), macrocephaly
• Behaviour: ADHD/hyperactivity, gaze avoidance, social anxiety, ASD traits
• Cause: FMR1 CGG repeat expansion (X chromosome)
• Anticipation: worsens in successive generations
• Females may have milder symptoms due to X-inactivation

⸻

⚠️ Common MRCPsych exam traps
• Diagnosing ASD without considering syndromic causes
• Mixing Fragile X with Rett (both have autistic traits but different sex + course)
• Forgetting macroorchidism appears after puberty, not at age 5

Question 10

Which gene mutation is associated with Fragile X syndrome?

A. MECP2
B. FMR1
C. HTT
D. APP
E. SOD1

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Answer 10

✅ Correct answer

B. FMR1

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Explanation (why correct + why others wrong)

✅ Why B is correct
• Fragile X = CGG trinucleotide repeat expansion in FMR1 gene on X chromosome
• Leads to methylation/silencing → deficiency of FMRP protein → neurodevelopmental impairment

❌ Why others are wrong (classic gene traps)
• MECP2 → Rett syndrome
• HTT → Huntington disease (CAG repeat)
• APP → familial Alzheimer’s (amyloid)
• SOD1 → ALS

⭐ High-yield facts
• Fragile X: CGG repeat (not CAG)
• Located on X chromosome
• Premutation carriers (esp women) can have FXPOI; older men can develop FXTAS (extra high yield in some banks)
• Anticipation phenomenon
• Genetic counselling essential

Question 11

What is the most common symptom of Fragile X syndrome?

A. Hyperactivity
B. Short stature
C. Muscle rigidity
D. Microcephaly
E. Coarse thick skin

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Answer 11

✅ Correct answer

A. Hyperactivity

Hyperactivity/ADHD symptoms are the commonest clinical presentation in Fragile X.

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Explanation

✅ Why A is correct
• Fragile X behavioural phenotype commonly includes:
• hyperactivity
• inattention
• impulsivity
• anxiety
• ASD traits

This is a classic Paper B “most common symptom” question.

⭐ High-yield facts
• Most common behavioural issue: ADHD symptoms
• Anxiety and gaze avoidance are common
• ASD traits common but not universal
• Macroorchidism becomes obvious post-puberty
• Many have sensory hypersensitivity
• Learning difficulties prominent even when IQ near-normal in some

Question 12

A 6-year-old boy has severe intellectual disability, self-mutilation (biting lips/fingers), and orange-coloured crystals in the diaper. What is the most likely diagnosis?

A. Fragile X syndrome
B. Rett syndrome
C. Lesch–Nyhan syndrome
D. Angelman syndrome
E. Prader–Willi syndrome

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Answer 12

✅ Correct answer

C. Lesch–Nyhan syndrome

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This stem is a “signature vignette”:
• Self-injury (biting lips/fingers) → classic
• Orange crystals / “sand” in diaper → uric acid crystalluria
• Male → X-linked recessive

Pathophysiology:
• HGPRT deficiency → failure of purine salvage → hyperuricaemia
• Leads to:
gout / kidney stones
dystonia/choreoathetosis/spasticity
severe neurobehavioural phenotype

⭐ High-yield facts (5–7)
• Lesch–Nyhan = HGPRT deficiency (X-linked)
• Purine salvage defect → hyperuricaemia
• Orange “sand” diapers = urate crystals
• Neuro: dystonia, choreoathetosis, spasticity
• Behaviour: self-mutilation (lip/finger biting)
• Can cause nephrolithiasis / gout
• Treatment: allopurinol lowers urate but doesn’t fix neuro features

Question 13

Which gene is associated with Rett syndrome?

A. MECP2
B. FMR1
C. HTT
D. APP
E. SOD1

⸻

Answer 13

✅ Correct answer

A. MECP2

⸻

Rett syndrome is caused by mutation in:

➡️ MECP2 gene (methyl-CpG-binding protein 2)
➡️ Located on the X chromosome

Pathophysiology:
• Abnormal transcription regulation
• Severe neurodevelopmental regression

Classic presentation:

✔ Female child
✔ Normal early development
✔ Regression at 6–18 months
✔ Loss of purposeful hand use
✔ Hand-wringing stereotypies
✔ Microcephaly (acquired)
✔ Severe intellectual disability

⭐ High-yield facts (Rett syndrome)
• Almost exclusively affects females
• X-linked dominant (male fetuses often non-viable)
• Regression after normal early development
• Hand-wringing movements are pathognomonic
• Seizures common
• Autistic features early
• Acquired microcephaly

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⚠️ Common exam traps
• Confusing Rett with autism (both have regression)
• Forgetting sex specificity (female predominance)
• Mixing MECP2 with FMR1

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🧠 One-line exam answer

Rett syndrome = MECP2 mutation on the X chromosome causing regression and hand-wringing in girls.

Question 14

A 7-year-old with intellectual disability has inverted sleep–wake cycle, self-hugging behaviour, aggression, hyperactivity, and brachycephaly. Which syndrome?

A. Fragile X
B. Smith–Magenis syndrome
C. Prader–Willi syndrome
D. Angelman syndrome
E. Lesch–Nyhan syndrome

⸻

Answer 14

✅ Correct answer

B. Smith–Magenis syndrome

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Explanation

✅ Why B is correct

Classic Smith–Magenis features:

✔ Chromosome 17p11.2 deletion
✔ Sleep disturbance due to inverted melatonin rhythm
✔ Self-hugging behaviour (very characteristic)
✔ Self-injury
✔ Aggression, impulsivity
✔ Developmental delay
✔ Distinct facial features (brachycephaly, midface hypoplasia)

⭐ High-yield facts
• Inverted circadian rhythm (melatonin abnormal)
• Self-hugging posture pathognomonic
• Sleep disturbance severe
• Aggressive outbursts common
• Intellectual disability
• Often mistaken for ADHD/ASD

Question 15

A 6-year-old has hyperphagia, obesity, hypotonia, almond-shaped eyes, and behavioural problems. Genetic testing shows genomic imprinting. Diagnosis?

A. Down syndrome
B. Turner syndrome
C. Beckwith–Wiedemann
D. Prader–Willi syndrome
E. Klinefelter syndrome

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Answer 15

✅ Correct answer

D. Prader–Willi syndrome

⸻

Explanation

✅ Why D is correct

Classic Prader–Willi triad:

✔ Neonatal hypotonia + feeding problems
➡️ Later hyperphagia + obesity
✔ Almond-shaped eyes
✔ Behavioural problems (tantrums, stubbornness)
✔ Short stature
✔ Hypogonadism

Genetics:
➡️ Loss of paternal genes on chromosome 15q11–13
➡️ Genomic imprinting

⭐ High-yield facts
• Neonatal hypotonia → hyperphagia later
• Severe obesity risk
• Growth hormone deficiency common
• Behavioural problems (skin picking)
• Mild–moderate intellectual disability
• Sleep apnea risk
• Opposite imprinting causes Angelman syndrome

Question 16

Which condition affects males and females equally?

A. ASD
B. ADHD
C. Prader–Willi syndrome
D. Fragile X syndrome
E. Rett syndrome

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Answer 16

✅ Correct answer

C. Prader–Willi syndrome

⸻

✅ Why C is correct

Prader–Willi is due to chromosomal imprinting, not sex-linked inheritance → equal sexes affected.

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❌ Why others are wrong
• ASD → male predominance (~4:1)
• ADHD → male predominance
• Fragile X → X-linked → males more severe
• Rett → predominantly females

⸻
⭐ High-yield facts
• Most neurodevelopmental disorders show male bias
• Exceptions often chromosomal imprinting disorders
• Rett: almost exclusively female
• Fragile X: X-linked male predominance

Question 17

Which inheritance pattern applies to Prader–Willi syndrome?

A. Autosomal dominant
B. Autosomal recessive
C. X-linked recessive
D. Genomic imprinting
E. Mitochondrial

⸻

Answer 17

✅ Correct answer

D. Genomic imprinting

⸻

✅ Why D is correct

Prader–Willi results from:

➡️ Loss of paternal expression of genes on chromosome 15q11–13
➡️ Maternal copy is imprinted (silenced)

Mechanisms:
• Paternal deletion (most common)
• Maternal uniparental disomy
• Imprinting defects

⸻

❌ Why other options are wrong

Not classical Mendelian inheritance — therefore not dominant, recessive, X-linked, or mitochondrial.

⸻

5️⃣ ⭐ High-yield facts
• Same region → Angelman syndrome if maternal genes lost
• Classic exam pairing:
Paternal loss → Prader–Willi
Maternal loss → Angelman
• Imprinting disorders often involve feeding problems or neurobehavioural syndromes

Question 18

A 3-year-old has developmental delay, frequent laughter, ataxia, happy demeanor, and hand-flapping. Genetic testing shows deletion on maternal chromosome 15. Diagnosis?

A. Deletion on maternal chromosome 15 — Angelman syndrome
B. Trisomy 21
C. MECP2 mutation
D. Deletion on paternal chromosome 15
E. FMR1 mutation

⸻

Answer 18

✅ Correct answer

A. Angelman syndrome (maternal deletion chromosome 15)

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3️⃣ Explanation (deep examiner logic)

✅ Why A is correct

Classic Angelman phenotype:

✔ Severe developmental delay
✔ Ataxia (“puppet-like” gait)
✔ Frequent laughter / happy affect
✔ Hand-flapping
✔ Microcephaly
✔ Seizures common

Genetics:

➡️ Loss of maternal gene expression at 15q11–13
➡️ Due to genomic imprinting

⭐ High-yield facts
• Angelman = maternal loss of chromosome 15 expression
• Severe intellectual disability
• Seizures common
• Minimal speech
• “Happy puppet” appearance
• Ataxic gait
• Sleep disturbance common

🧠 One-line exam answer
Happy child with ataxia and seizures → Angelman syndrome (maternal deletion chromosome 15).

Question 19

A child has a high-pitched cat-like cry, hypertelorism, microcephaly, hypotonia, and severe intellectual disability. Diagnosis?

A. Williams syndrome
B. Cri-du-chat syndrome
C. Fragile X syndrome
D. Down syndrome
E. Turner syndrome

⸻

Answer 19

✅ Correct answer

B. Cri-du-chat syndrome

⸻

✅ Why B is correct

Signature feature:

➡️ High-pitched “cat-like” cry (due to laryngeal abnormality)

Genetics:
➡️ Deletion of short arm of chromosome 5 (5p deletion)

Other features:
• Microcephaly
• Severe ID
• Hypotonia
• Hypertelorism
• Growth delay

⭐ High-yield facts
• Cri-du-chat = 5p deletion
• Cry disappears with age
• Severe developmental delay
• Feeding difficulties in infancy
• Facial dysmorphism

Question 20

A 1-year-old has feeding difficulties, epicanthic folds, flat nasal bridge, upward slanting eyes, hypotonia, and congenital heart disease. Diagnosis?

A. Turner syndrome
B. Williams syndrome
C. Down syndrome
D. Noonan syndrome
E. Prader–Willi syndrome

⸻

Answer 20

✅ Correct answer

C. Down syndrome

⸻

✅ Why C is correct

Classic Down syndrome features:

✔ Epicanthic folds
✔ Flat nasal bridge
✔ Upward slanting palpebral fissures
✔ Hypotonia (“floppy infant”)
✔ Feeding difficulties
✔ Congenital heart disease (especially AVSD)

⭐ High-yield facts
• Trisomy 21 (most cases due to nondisjunction)
• Increased Alzheimer risk (APP gene on chromosome 21)
• Increased leukemia risk
• Thyroid dysfunction common
• Atlantoaxial instability
• Hearing and vision problems common

Question 21

What is the risk of Down syndrome for a 30-year-old mother?

⸻

Answer 21

✅ Correct answer

≈ 1 in 900–1000

⸻

Risk increases with maternal age due to meiotic nondisjunction.

⭐ High-yield facts
• Maternal age is strongest risk factor
• Risk rises exponentially after 35
• Screening recommended in pregnancy
• Robertsonian translocation causes some cases independent of age

Question 22

Which genetic syndrome carries a 20–30% risk of psychosis?

A. Down syndrome
B. Fragile X syndrome
C. Prader–Willi syndrome
D. Velocardiofacial syndrome (22q11 deletion)
E. Williams syndrome

Answer 22

✅ Correct answer

D. Velocardiofacial syndrome (22q11 deletion)

⸻

✅ Why D is correct

22q11 deletion (DiGeorge/VCFS):

✔ One of the strongest known genetic risk factors for schizophrenia
✔ Psychosis risk ~20–30%
✔ Cognitive impairment common

Associated features:
• Cardiac defects
• Cleft palate
• Immune deficiency
• Hypocalcaemia
• Facial dysmorphism

⸻

❌ Why others are wrong
• Down syndrome → dementia risk, not schizophrenia
• Fragile X → ADHD/autism traits
• Prader–Willi → behavioural issues
• Williams → anxiety + hypersociability

⭐ High-yield facts
• Called DiGeorge / velocardiofacial syndrome
• Chromosome 22q11 deletion
• Strongest single genetic risk for schizophrenia
• May present with learning disability + psychosis in adolescence
• Hypocalcaemia can cause seizures

Question 23

A child presents with facial dysmorphism (long philtrum), growth deficiency, and developmental delays. The mother reports heavy alcohol use during pregnancy. What is the diagnosis?

A. Cri-du-chat syndrome
B. Down syndrome
C. Fragile X syndrome
D. Prader–Willi syndrome
E. Fetal alcohol syndrome

⸻

Answer 23

✅ Correct answer

E. Fetal alcohol syndrome

⸻

✅ Why E is correct (examiner logic)

Classic FAS triad:

✔ Characteristic facial features
✔ Growth restriction
✔ Neurodevelopmental impairment

Facial dysmorphism in FAS:
• Smooth/long philtrum
• Thin upper lip
• Short palpebral fissures
• Flat midface
• Microcephaly common

History of maternal alcohol exposure is decisive.

⭐ High-yield facts to memorise
• Alcohol is the most common preventable cause of intellectual disability
• No safe amount of alcohol in pregnancy
• FAS causes permanent brain damage
• ADHD and behavioural problems common
• Increased risk of mood disorders later
• Microcephaly frequent
• Growth failure persists postnatally

Question 24

FMR1 CGG repeat expansion
X-linked → males more affected
Most common inherited ID
Anticipation phenomenon
Females milder due to X-inactivation

Large ears, long face, macrocephaly
Macroorchidism after puberty
Hyperextensible joints, hypotonia, flat feet (pes platus)
High arched palate
Pectus excavatum
Mitral valve prolapse
Seizures in 10%

ADHD and ASD features common
Social anxiety and gaze avoidance

Answer 24

Fragile X Syndrome

Question 25

MECP2 mutation Almost exclusively females Normal early development → regression Loss of purposeful hand use Hand-wringing stereotypies Acquired microcephaly Severe intellectual disability Seizures common

Answer 25

Rett Syndrome

Question 26

Neurodevelopmental condition most associated with psychosis:

Answer 26

Answer: Fragile X syndrome Explanation: Among genetic neurodevelopmental disorders, Fragile X has a relatively higher risk of psychotic symptoms compared with others listed in typical exam options.

Question 27

Pale child, blue eyes, seizures, hyperactivity:

Answer 27

Answer: Phenylketonuria (PKU) Explanation: Untreated PKU leads to intellectual disability, seizures, behavioral problems, and hypopigmentation (fair skin, blue eyes) due to impaired melanin synthesis.

Question 28

Gaze avoidance and macro-orchidism:

Answer 28

Answer: Fragile X syndrome Explanation: Most common inherited cause of intellectual disability and autism. Features include long face, large ears, macroorchidism, social anxiety, and gaze avoidance.

Question 29

Rett syndrome characteristic feature:

Answer 29

Answer: Repetitive hand-wringing movements Explanation: Rett syndrome (MECP2 mutation) shows developmental regression after normal early development, loss of purposeful hand use, and stereotyped hand-wringing.

Question 30

Self-hugging, sleep problems, self-harm:

Answer 30

Answer: Smith–Magenis syndrome Explanation: Characterized by self-injurious behavior, sleep disturbance (inverted melatonin rhythm), intellectual disability, and distinctive behaviors such as self-hugging.

Question 31

Hyperuricemia, gout, self-injurious behavior:

Answer 31

Answer: Lesch–Nyhan syndrome Explanation: X-linked recessive deficiency of HGPRT causing uric acid overproduction, neurological dysfunction, and classic self-mutilation (lip/finger biting).

Question 32

newborn has a distinctive high-pitched cat-like cry, microcephaly, hypertelorism, and low birth weight. What is the diagnosis?

Answer 32

Answer: 👉 Cri-du-chat syndrome ⸻ Explanation: Cri-du-chat syndrome = chromosome 5p deletion 🗣 Name literally means “cry of the cat” in French. ⸻ Key clinical features: 🐱 High-pitched cat-like cry (due to laryngeal abnormality) 🧠 Microcephaly 👶 Low birth weight 👁 Hypertelorism 📉 Severe intellectual disability 👶 Hypotonia

Question 33

A 3-year-old child has severe intellectual disability, no speech, ataxic gait, happy demeanour with frequent laughter, and hand flapping. What is the most likely diagnosis?

Answer 33

Answer: 👉 Angelman syndrome Explanation: Classic Angelman features (“happy puppet syndrome”): 🧠 Severe intellectual disability 🗣️ Minimal or absent speech 😄 Inappropriate laughter / happy affect 🚶 Ataxia 👏 Hand flapping ⚡ Seizures common Genetic basis: 👉 Maternal deletion of chromosome 15q11–13

Question 34

Which behavioural feature is characteristic of Prader-Willi syndrome?

Answer 34

Answer: 👉 Hyperphagia and food-seeking behaviour Explanation: Key behavioural hallmark: 🍔 Insatiable appetite 🔒 Food hoarding 🚫 Lack of satiety ⚖️ Severe obesity risk Associated behavioural profile: • Temper outbursts • Stubbornness • Skin picking (also high yield)

Question 35

What is the characteristic hand movement in Rett syndrome?

Answer 35

Answer: 👉 Hand-wringing / hand-washing movements Explanation: This is a pathognomonic sign. Classic features: 👐 Repetitive hand-wringing 🧼 Hand-washing motions 🚫 Loss of purposeful hand use These movements appear after developmental regression.

Question 36

What is the typical developmental pattern in Rett syndrome?

Answer 36

Answer: 👉 Normal development then regression Explanation (Exam-focused): Rett syndrome has a distinctive developmental trajectory: 🟢 Initially normal development (≈ first 6–18 months) 🔴 Then progressive loss of acquired skills Loss typically involves: • Speech • Motor abilities • Social interaction • Purposeful hand use ⚠️ This pattern is one of the strongest diagnostic clues.

Question 37

A 2-year-old girl with previously normal development now shows loss of hand skills, hand-wringing, and language regression. What is the likely diagnosis?

Answer 37

Answer: 👉 Rett syndrome ⸻ Explanation: Classic triad: 👧 Female child 🔻 Developmental regression 👐 Loss of purposeful hand use → replaced by hand-wringing 🗣 Language loss This is essentially a textbook description of Rett syndrome.

Question 38

Williams syndrome is characterized by which behavioral phenotype?

Answer 38

Answer: 👉 Hypersociability and anxiety ⸻ 🧠 Explanation: Williams syndrome = distinctive “cocktail-party personality”: 🫂 Extremely friendly with strangers 🗣 Strong verbal abilities 😰 Significant anxiety 🎵 Often musical talent 💓 Cardiovascular disease (supravalvular aortic stenosis) PLUS • “Elfin facies” • Hypercalcaemia • Supravalvular aortic stenosis

Question 39

Which chromosomal abnormality causes Cri-du-chat syndrome?

Answer 39

Answer: 👉 Deletion on chromosome 5p ⸻ 🧬 Explanation: Cri-du-chat syndrome is caused by: 👉 Deletion of the **short arm**of chromosome 5 (5p−) Key features: 🐱 High-pitched cat-like cry (laryngeal abnormality) 🧠 Microcephaly 📉 Severe intellectual disability 👶 Low birth weight 👁 Hypertelorism 💪 Hypotonia ⚠️ The cry often fades with age, but intellectual disability persists. ❗ Other deletions: Deletion on chromosome 15 → • Paternal deletion → Prader-Willi • Maternal deletion → Angelman 22q11 deletion → DiGeorge syndrome X chromosome monosomy → Turner syndrome

Question 40

Which syndrome is characterised by inappropriate laughter, ataxia, and severe intellectual disability?

Answer 40

👉 Angelman syndrome

Question 41

Which syndrome has severe speech impairment but relatively good receptive language?

Answer 41

👉 Angelman syndrome

Question 42

What is the gender distribution in Prader-Willi syndrome?

Answer 42

Answer: 👉 Equal (1:1) Explanation: Prader-Willi is not sex-linked. It results from genomic imprinting on chromosome 15, so males and females are affected equally. 🔑 Contrast with X-linked disorders (male predominance): • Fragile X • Lesch-Nyhan • Duchenne muscular dystrophy

Question 43

What is the most common psychiatric symptom in adults with Fragile X syndrome? Options: A. Psychosis B. Depression C. Social anxiety D. OCD E. Bipolar disorder

Answer 43

✅ Correct answer: C. Social anxiety 🧠 Explanation Natural history: • Childhood → hyperactivity, attentional problems • Adolescence/adulthood → prominent social anxiety Adults often appear shy, avoidant, and socially withdrawn.

Question 44

Fragile X Syndrome

Answer 44

👉 Male with intellectual disability 👉 Autistic features 👉 Gaze avoidance 👉 Large ears / long face 👉 Macroorchidism (post-puberty) ➡️ Think Fragile X syndrome immediately

Question 45

Prader-Willi syndrome results from which genetic abnormality?

Answer 45

Answer: 👉 Deletion of the paternal chromosome 15 (15q11–q13) Explanation: Prader-Willi occurs when the paternal copy of chromosome 15 is missing or inactive. Mechanisms: • Paternal deletion (~70%) • Maternal uniparental disomy (~25%) • Imprinting defects 💡 Key concept: Loss of paternal expression

Question 46

Which inheritance pattern explains both Prader-Willi and Angelman syndromes?

Answer 46

Answer: 👉 Genomic imprinting Explanation: Genomic imprinting = gene expression depends on which parent the gene came from.

Question 47

Q24. In Fragile X syndrome, how does performance IQ compare to verbal IQ? Options: A. Performance IQ greater than verbal IQ B. Verbal IQ greater than performance IQ C. Both are equally affected D. Neither is affected E. Variable pattern

Answer 47

✅ Correct answer: A. Performance IQ greater than verbal IQ 🧠 Explanation Typical cognitive profile: • Relative strength → visual-spatial / non-verbal tasks • Weakness → expressive language, pragmatic language • Speech often verbose but poorly organised Hence performance IQ > verbal IQ.

Question 48

What physical finding in post-pubertal males strongly suggests Fragile X syndrome? Options: A. Microcephaly B. Webbed neck C. Macroorchidism D. Polydactyly E. Cleft palate

Answer 48

✅ Correct answer: C. Macroorchidism 🧠 Explanation Macroorchidism = enlarged testes. Key points: • Develops after puberty • Highly characteristic of Fragile X • Useful diagnostic clue in adolescents/adults

Question 49

Which disorder is associated with inverted circadian rhythm of melatonin?

Answer 49

👉 Answer: Smith-Magenis syndrome 👉 This is a VERY testable association

Question 50

Turner syndrome is characterized by which karyotype?

Answer 50

Answer: 👉 45,X ⸻ 🧬 Explanation: Turner syndrome = monosomy X Karyotype: 👉 45,X Occurs only in females. ⸻ Key features: 📏 Short stature 🦢 Webbed neck 🛡️ Shield chest 💔 Coarctation of the aorta 🥚 Gonadal dysgenesis → primary amenorrhoea 🧠 Normal intelligence (often mild visuospatial difficulties)

Question 51

5-year-old boy presents with compulsive self-biting causing tissue damage, dystonia, intellectual disability, and hyperuricemia. What is the diagnosis?

Answer 51

Answer: 👉 Lesch-Nyhan syndrome ⸻ 🧬 Explanation: Lesch-Nyhan syndrome = HGPRT deficiency 👉 X-linked recessive disorder of purine metabolism ⸻ Classic tetrad: 🩸 Hyperuricemia → gout / kidney stones 🧠 Intellectual disability 🌀 Dystonia / movement disorder 🦷 Compulsive self-mutilation (especially biting lips/fingers) Self-injury is the hallmark feature.

Question 52

A child has elfin facies, cardiovascular problems, intellectual disability but relatively good verbal skills, and is excessively friendly with strangers. What syndrome is this?

Answer 52

Answer: 👉 Williams syndrome ⸻ 🧬 Explanation: Classic Williams syndrome triad: 👶 Elfin facies 🫂 Hypersociability 🗣 Relative strength in language 💓 Supravalvular aortic stenosis 🧪 Hypercalcaemia Children are often described as: 👉 “Overly friendly” 👉 “No stranger danger”

Question 53

❓ What is the prevalence of pica in severe intellectual disability?

Answer 53

Answer: Up to 15%.

Question 54

Which behavioural feature is most characteristic of Fragile X syndrome? Options: A. Hyperphagia B. Self-hugging C. Gaze avoidance and social anxiety D. Happy demeanour with laughter E. Compulsive self-biting

Answer 54

✅ Correct answer: C. Gaze avoidance and social anxiety 🧠 Explanation Fragile X syndrome has a distinctive behavioural phenotype: • Prominent gaze avoidance • Marked social anxiety • Shyness • Autistic-like social difficulties • Hyperactivity in childhood These features are often more pronounced than core autistic social reciprocity deficits.

Question 55

A boy has severe self-biting causing tissue damage, dystonia, developmental delay, and hyperuricaemia.

Answer 55

👉 Answer: Lesch-Nyhan syndrome 💡 Why: 🚨 MOST specific clue = self-mutilation + hyperuricaemia Classic triad: 🦷 Compulsive self-biting 🌀 Dystonia / choreoathetosis 🩸 Hyperuricemia → gout / stones

Question 56

Which disorder is caused by HGPRT deficiency?

Answer 56

👉 Answer: Lesch-Nyhan syndrome 🔬 X-linked recessive 🧬 Purine salvage pathway defect

Question 57

Noonan syndrome is often confused with which condition due to similar features? Options A. Down syndrome B. Turner syndrome C. Fragile X syndrome D. Williams syndrome E. Prader-Willi syndrome ⸻

Answer 57

✅ Correct Answer B. Turner syndrome ⸻ 🎯 High-Yield for MRCPsych? 🟡 Moderate yield Genetic syndrome comparisons appear occasionally in learning disability and neurodevelopment sections. ⸻ 🧠 Explanation (Exam Logic) Noonan syndrome shares several physical features with Turner syndrome, including: • Short stature • Webbed neck • Congenital heart defects However: • Turner syndrome occurs only in females (45,X) • Noonan syndrome occurs in both sexes and has normal chromosomes Because of these similarities, Noonan syndrome has historically been called: 👉 “Male Turner syndrome” ⸻ ⭐ High-Yield Facts 1️⃣ Noonan syndrome is autosomal dominant. 2️⃣ Often caused by mutations in PTPN11 gene. 3️⃣ Common cardiac defect: pulmonary valve stenosis. 4️⃣ Facial features include hypertelorism and low-set ears. 5️⃣ Mild learning difficulties may occur.

Question 58

A girl with apparently normal IQ but visuospatial difficulties. What is the most likely diagnosis? Options: A. Angelman syndrome B. Rett syndrome C. Fragile X syndrome D. Turner syndrome E. Foetal alcohol syndrome ⸻

Answer 58

✅ Correct Answer: D. Turner syndrome ⸻ 🧠 Why this is correct (exam logic) 👉 Key trigger: • Female • Normal IQ • Specific deficit → visuospatial impairment ✔ This is the classic cognitive profile of: ➡ Turner syndrome ⸻ ❌ Why others are wrong • Angelman → severe ID + happy demeanour • Rett → regression, hand-wringing • Fragile X → intellectual disability • Foetal alcohol → global impairment + facial features ⸻ 🚨 High-yield Turner cognitive profile 👉 Think: ➡ Normal verbal IQ ↓ Visuospatial ↓ executive function ⸻ 💣 3 High-yield facts 1. Karyotype = 45,XO 2. Short stature + streak ovaries 3. Coarctation of aorta common

Question 59

Cornelia de Lange syndrome features include: Options A. Hyperphagia and obesity B. Synophrys (joined eyebrows) and limb abnormalities C. Cat-like cry and microcephaly D. Self-hugging and sleep disturbance E. Hypersociability and cardiac defects ⸻

Answer 59

✅ Correct Answer B. Synophrys (joined eyebrows) and limb abnormalities ⸻ 🎯 High-Yield for MRCPsych? 🟡 Moderate yield Genetic syndromes appear occasionally in learning disability and neurodevelopment questions. ⸻ 🧠 Explanation (Exam Logic) Cornelia de Lange syndrome is a congenital condition characterized by: • Distinct facial features • Limb abnormalities • Developmental delay • Intellectual disability ⸻ ⭐ High-Yield Facts 1️⃣ Characteristic feature: synophrys (joined eyebrows). 2️⃣ Associated with upper limb abnormalities. 3️⃣ Often involves growth retardation. 4️⃣ Patients have moderate–severe intellectual disability. 5️⃣ Behavioural features may include autistic traits.

Question 60

Which condition is X-linked and associated with progressive muscular weakness? Options A. Fragile X syndrome B. Duchenne muscular dystrophy C. Turner syndrome D. Prader-Willi syndrome E. Tuberous sclerosis ⸻

Answer 60

✅ Correct Answer B. Duchenne muscular dystrophy ⸻ 🎯 High-Yield for MRCPsych? 🟢 HIGH YIELD X-linked disorders and neurodevelopmental syndromes are commonly tested in MRCPsych learning disability topics. ⸻ 🧠 Explanation (Exam Logic) Duchenne muscular dystrophy (DMD) is an X-linked recessive disorder caused by mutation in the dystrophin gene. It leads to progressive muscle degeneration. Symptoms typically begin: 👉 before age 5 ⸻ ⭐ High-Yield Facts 1️⃣ Caused by mutation in the dystrophin gene on chromosome Xp21. 2️⃣ Affects boys almost exclusively. 3️⃣ Early sign: Gowers’ sign (using hands to climb up legs when standing). 4️⃣ Serum creatine kinase (CK) levels are markedly elevated. 5️⃣ Many patients develop cardiomyopathy and respiratory failure.

Question 61

A 5-year-old boy with short stature and hypertelorism. His mother complains that he is hyperactive and very noisy.”

Answer 61

✅ Answer: Cri-du-chat syndrome ⸻ 🧠 Explanation: • Key clues: • “very noisy” → abnormal cry (cat-like cry) • facial features (hypertelorism) • developmental issues 👉 Cri-du-chat = chromosome 5 deletion ⸻ ❌ Trap: • Fragile X → no “cat cry” • Turner → female only ⸻ 🔥 High-yield: 👉 “NOISY child + abnormal cry = Cri-du-chat”

Question 62

🧒 Epilepsy-Specific Syndromes

Answer 62

⭐ Landau-Kleffner Syndrome VERY testable • Acquired epileptic aphasia • Language regression • Seizures • Previously normal development ⸻ ⭐ West Syndrome • Infantile spasms • Often associated with TSC • Hypsarrhythmia on EEG

Question 63

An 11-year-old child presents with epilepsy and language regression with language at 6-year-old level. What is the most likely diagnosis? A. Fragile X syndrome B. Rett syndrome C. Landau-Kleffner syndrome D. Autism spectrum disorder E. Down syndrome

Answer 63

✅ Answer: C. Landau-Kleffner syndrome Explanation (high-yield): • Acquired epileptic aphasia • Previously normal child develops language loss • Associated with seizures and abnormal EEG • Typically onset 3–7 years but can present later • Comprehension impaired → may mimic autism 👉 Buzz phrase: “Regression of language + epilepsy in a previously normal child”

Question 64

An 8-year-old boy who suffers from seizures and has recently developed mutism.”

Answer 64

✅ Answer: Landau-Kleffner syndrome ⸻ 🧠 Explanation: • Classic triad: • normal early development • seizures • language regression (mutism) ⸻ ❌ Trap: • Autism → earlier onset • Rett → girls + regression ⸻ 🔥 High-yield: 👉 “Seizures + loss of speech = Landau-Kleffner”

Question 65

A short 12-year-old girl with a webbed neck, whose recent CT scan revealed a narrowed aorta.”

Answer 65

✅ Answer: Turner syndrome ⸻ 🧠 Explanation: Classic: • short stature • webbed neck • coarctation of aorta ⸻ ❌ Trap: • Noonan → similar but NOT female-only ⸻ 🔥 High-yield: 👉 “Webbed neck + coarctation = Turner”

Question 66

A 14-year-old boy who has a history of social anxiety. In clinic he appears shy and avoids looking at you directly.”

Answer 66

✅ Answer: Fragile X syndrome ⸻ 🧠 Explanation: Key behavioural phenotype: • social anxiety • gaze avoidance • autism-like traits ⸻ ❌ Trap: • Autism → but here genetic syndrome clues ⸻ 🔥 High-yield: 👉 “Gaze avoidance = Fragile X (exam favourite)” ⸻

Question 67

A 30-year-old man with clumsy gait, repeated falls and visual problems reports that his grandfather reportedly developed the same condition and died at an age of 41 after myocardial infarction. The most likely diagnosis to be considered is A. Wilson’s disease B. MELAS syndrome C. Fragile X syndrome D. Myotonic dystrophy E. Friedreich’s ataxia ⸻

Answer 67

✅ Correct answer: 👉 E. Friedreich’s ataxia ⸻ 🔍 Explanation Key clues: • Ataxia (clumsy gait + falls) • Visual problems • Cardiac disease → early death (MI) • Family history 👉 Classic for Friedreich’s ataxia ⸻ ❌ Why others are wrong: • Wilson’s → liver + psychiatric + Kayser-Fleischer rings • MELAS → stroke-like episodes • Fragile X → intellectual disability, not ataxia • Myotonic dystrophy → muscle weakness, not classic ataxia ⸻ 💥 High-yield Paper B facts Friedreich’s ataxia: • Autosomal recessive • GAA repeat on chromosome 9 • Features: Ataxia Peripheral neuropathy Hypertrophic cardiomyopathy (VERY IMPORTANT) Diabetes • Cause of death: 👉 Cardiac disease ⸻ In Friedreich,s ataxia the spinal and peripheral nerves and cerebellum degenerate, a ecting balance and movement and sensory functions but with intact cognition. The disorder also causes problems in the heart and spine, and some people with the condition develop diabetes. Various forms of heart disease often accompany Friedreich's ataxia, including hypertrophic cardiomyopathy, myocardial brosis, and cardiac failure. Heart block is also common. Heart disease is the most common cause of death.

Question 68

A subcultural rather than neuropathological explanation for learning disability is supported by which of the following? Select one: A. Facial dysmorphic features are common B. Existence of profound degree of learning disability C. Even distribution of LD across different socioeconomic groups of the population D. Mild learning disability E. Frequent behavioural phenotypes ⸻

Answer 68

✅ Correct answer: 👉 D. Mild learning disability ⸻ 🔍 Explanation (exam logic) • Subcultural LD → due to environmental/social factors • Neuropathological LD → due to organic brain pathology 👉 Key discriminator: • Mild LD → subcultural • Severe/profound LD → organic ⸻ ❌ Why others are wrong: • A. Dysmorphic features → organic (genetic syndromes) • B. Profound LD → organic • C. Subcultural LD is NOT evenly distributed → linked to low SES • E. Behavioural phenotypes → syndromic (organic) ⸻ 💥 High-yield facts • Mild LD = ~85% of LD → usually subcultural • Severe LD → strongly organic • Dysmorphism = think genetic cause

Question 69

Which of the following genetic syndromes is known to have an association with the schizotypal disorder? Select one: A. Turner’s syndrome B. Fragile X syndrome C. Rett’s syndrome D. West syndrome E. Lennox Gastaut syndrome ⸻

Answer 69

✅ Correct answer: 👉 B. Fragile X syndrome ⸻ 🔍 Explanation • Fragile X → neurodevelopmental + personality traits • Includes: • Autism • ADHD • Schizotypal / schizoid traits ⸻ ❌ Why others are wrong: • A. Turner → social difficulties, not schizotypal • C. Rett → severe neurodevelopmental regression • D/E → epilepsy syndromes, not personality traits ⸻ 💥 High-yield facts • CGG repeat expansion (FMR1) • X-linked • Long face + macroorchidism ⸻ 🎯 Takeaway 👉 Fragile X = autism + schizotypal traits

Question 70

Lennox-Gastaut syndrome is characterized by Select one: A. Triad of infantile spasms, spike-wave complex and mental retardation B. Spontaneous recovery C. Adolescent onset D. Primarily caused by a metabolic encephalopathy E. Responds well to antiepileptics ⸻

Answer 70

✅ Correct answer: 👉 A. Triad of infantile spasms, spike-wave complex and mental retardation ⸻ 🔍 Explanation • Lennox-Gastaut = severe childhood epilepsy syndrome Key features: • Multiple seizure types • EEG: slow spike-wave • Intellectual disability 👉 Often evolves from infantile spasms → hence option A accepted in exams ⸻ ❌ Why others are wrong: • B. No → poor prognosis • C. Onset is childhood (1–8 yrs), not adolescence • D. Can be structural/idiopathic, not mainly metabolic • E. Poor response to treatment ⸻ 💥 High-yield facts • Resistant epilepsy • Developmental impairment • Lifelong condition

Question 71

Diagnostic overshadowing is an often-debated issue in the psychiatry of learning disabilities. This concept refers to Select one: A. Providing an insufficient diagnostic explanation for genetically determined syndromes B. Making more than one diagnosis for a behavioural problem C. Making more than one diagnosis for a physical health problem D. Attributing a psychiatric symptom to a behavioural phenotype E. Attributing a health issue to an already existing health issue ⸻

Answer 71

✅ Correct answer: 👉 E. Attributing a health issue to an already existing health issue ⸻ 🔍 Explanation (exam logic) 👉 Diagnostic overshadowing = “Everything is blamed on the existing diagnosis” • Patient has LD → develops new symptom • Clinician says: “It’s just their LD” → misses real diagnosis

Question 72

HGPRT deletion mutation is linked to which of the following conditions? Select one: A. Rett Syndrome B. Lesch-Nyhan Syndrome C. Tuberous Sclerosis D. Williams syndrome E. Prader-Willi Syndrome ⸻

Answer 72

✅ Correct answer: 👉 B. Lesch-Nyhan syndrome ⸻ 🔍 Explanation • HGPRT deficiency → impaired purine salvage • → ↑ uric acid • → neurological + behavioural syndrome ⸻ ❌ Why others are wrong: • A. Rett → MECP2 mutation • C. Tuberous sclerosis → TSC1/TSC2 • D. Williams → chromosome 7 deletion • E. Prader-Willi → paternal chromosome 15 deletion ⸻ 💥 High-yield facts • X-linked recessive • Self-mutilation (classic!!!) • Aggression + gout