A 34-year-old woman with major depressive disorder presents for follow-up. She has failed adequate trials of fluoxetine, paroxetine, and venlafaxine over the past 3 years. She reports excellent adherence and denies substance use. Serum drug levels were consistently subtherapeutic. Physical examination and laboratory results are unremarkable.
Which of the following is the most likely explanation for her treatment resistance?
A. Reduced serotonin receptor sensitivity causing pharmacodynamic tolerance
B. Ultra-rapid CYP2D6 metabolism leading to accelerated drug clearance
C. Poor gastrointestinal absorption due to subclinical malabsorption
D. Increased P-glycoprotein activity at the blood–brain barrier
E. Nonadherence masked by inaccurate self-reporting
B. Ultra-rapid CYP2D6 metabolism leading to accelerated drug clearance
Rationale
This patient has:
* Multiple antidepressant failures
* Across drug classes
* With documented subtherapeutic levels
* And good adherence
Boards love to trick you into blaming “nonadherence.” When labs support adherence, suspect CYP polymorphisms.
Two siblings, ages 6 and 3, present with chronic productive cough, recurrent pneumonia, and pancreatic insufficiency. Both parents are healthy with no known medical conditions. Genetic testing confirms cystic fibrosis in both children.
What is the most accurate recurrence risk for future children of these parents?
A. 0%
B. 25%
C. 50%
D. 75%
E. 100%
B. 25%
Rationale
Cystic fibrosis is an autosomal recessive disorder.
This means:
* Both parents are carriers (heterozygous)
* Each child receives one allele from each parent
Recessive disease = 25% affected, 50% carrier, 25% normal—every pregnancy.
A 52-year-old man presents with progressive muscle weakness and cognitive decline. His father and grandfather died in their 50s with similar symptoms. Genetic testing confirms an autosomal dominant neurodegenerative disorder.
Which statement best describes the genetic risk to his children?
A. All children will inherit the disease
B. Each child has a 25% risk of inheritance
C. Each child has a 50% risk of inheritance
D. Only male children are at risk
E. Risk depends on maternal genotype
C. Each child has a 50% risk of inheritance
Rationale
Autosomal dominant disorders:
* Require only one abnormal allele
* Are typically heterozygous
* Show vertical transmission
Autosomal dominant = 50% risk, no skipping generations.
A 38-year-old woman delivers an infant with hypotonia, epicanthal folds, and congenital heart disease. Karyotype shows trisomy 21. Further testing reveals a Robertsonian translocation involving chromosomes 14 and 21.
Which statement is most appropriate regarding future pregnancies?
A. Recurrence risk is negligible because this was due to nondisjunction
B. Future risk is unrelated to parental genetics
C. Both parents should undergo chromosomal analysis
D. Only maternal age determines recurrence risk
E. Genetic counseling is unnecessary
C. Both parents should undergo chromosomal analysis
Rationale
Most Down syndrome cases are due to nondisjunction.
However:
This case involves a Robertsonian translocation.
This means:
* One parent may be a balanced carrier
* Carrier parents have increased recurrence risk
* Multiple affected children possible
Down syndrome + translocation = evaluate parents.
An 8-year-old boy presents with easy bruising and prolonged bleeding. He is diagnosed with hemophilia A. His maternal uncles were also affected. His mother is asymptomatic.
What is the probability that his mother is a carrier?
A. 0%
B. 25%
C. 50%
D. 75%
E. Nearly 100%
E. Nearly 100%
Hemophilia A is X-linked recessive.
Key facts:
* Affected males have only one X
* That X must come from mother
* Father provides Y
Affected male with X-linked disease = mother is a carrier until proven otherwise.
A 28-year-old patient with a family history of beta-thalassemia undergoes genetic testing. The results show a base pair substitution in the beta-globin gene that does not alter the amino acid sequence due to codon redundancy. The APRN explains that this mutation is most likely:
A. Missense, leading to a dysfunctional hemoglobin protein.
B. Nonsense, causing premature termination of the polypeptide chain.
C. Silent, with no clinical consequences.
D. Frameshift, shifting the reading frame and likely causing severe disease.
C. Silent, with no clinical consequences.
Full Rationale: According to the chapter (pages 143-144, Fig. 4.6), mutations are alterations in genetic material. Base pair substitutions can be silent if they do not change the amino acid due to the redundancy of the genetic code (64 codons for 20 amino acids). In beta-thalassemia, pathogenic mutations are often nonsense (premature stop codon) or frameshift (insertion/deletion not in multiples of 3, shifting the frame and often leading to early stops). However, this substitution is silent, as it exploits codon degeneracy and has no effect on the protein. The chapter notes that many substitutions are silent and have no consequence, distinguishing them from missense (single amino acid change) or nonsense mutations.
Teaching Points: Trick overcome: Don’t assume all substitutions are pathogenic—recall codon redundancy (e.g., multiple codons for serine). Trap avoidance: In exams, distractors like A/B/D play on common diseases; cross-check if the mutation affects the amino acid. Pitfall prevention: Memorize mutation types with mnemonics like “Silent = Same (no change); Missense = Mistake (wrong acid); Nonsense = Nonsense (stops early); Frameshift = Frame wrecked (shifted sequence).” Practice by listing examples from the chapter (e.g., sickle cell as missense).
A newborn screens positive for phenylketonuria (PKU), an autosomal recessive disorder. The parents deny exposure to environmental toxins, but the APRN notes the mutation rate for this gene is approximately 10^{-6} per generation. The most accurate explanation for the mutation’s origin is:
A. Induced by mutagens like radiation or chemicals, despite no reported exposure.
B. Spontaneous, occurring naturally without external agents.
C. Frameshift due to insertion from viral integration.
D. Nonsense from base pair substitution triggered by consanguinity.
B. Spontaneous, occurring naturally without external agents.
Full Rationale: The chapter (page 144) states that mutations are rare, with spontaneous rates of 10^{-4} to 10^{-7} per gene per generation, varying by gene. Mutagens (e.g., radiation, nitrogen mustard) increase rates, but most mutations, including in PKU, are spontaneous. Consanguinity increases recessive disease risk but doesn’t cause mutations.
Trap avoidance: Consanguinity (D) is a red herring for AR diseases; it uncovers existing mutations, doesn’t create them. Strategy: When no exposure history, default to spontaneous; link to replication proofreading by DNA polymerase.
During a lecture on gene expression, an APRN student is asked about the process where mRNA is synthesized from DNA. A mutation in the promoter region leads to reduced transcription factor binding. Which statement accurately describes this scenario?
A. Transcription occurs in the 3’ to 5’ direction, replacing thymine with uracil in the template strand.
B. The template strand is read 5’ to 3’, producing mRNA with adenine pairing to thymine.
C. RNA polymerase binds the promoter, synthesizing mRNA in the 5’ to 3’ direction using the template strand read 3’ to 5’.
D. Translation factors initiate at the promoter, leading to polypeptide formation in the nucleus.
C. RNA polymerase binds the promoter, synthesizing mRNA in the 5’ to 3’ direction using the template strand read 3’ to 5’.
Full Rationale: The chapter (pages 145-146, Fig. 4.7) describes transcription: RNA polymerase binds the promoter (start sequence), reads the DNA template strand 3’ to 5’, synthesizing mRNA 5’ to 3’ (antiparallel). Uracil replaces thymine. Mutation in promoter reduces transcription factor binding (Fig. 4.8), lowering gene expression. Option A reverses directionality; B has wrong base pairing (adenine pairs uracil in RNA); D confuses transcription with translation (cytoplasm, ribosome).
Teaching Points: Trick overcome: Directionality traps—memorize “Synthesis always 5’ to 3’; template read 3’ to 5’.” Trap avoidance: Don’t mix DNA (thymine) with RNA (uracil); chapter emphasizes uracil pairs adenine. Pitfall prevention: Separate transcription (nucleus, mRNA) from translation (cytoplasm, protein); use visuals like Fig. 4.7. Strategy: Draw arrows for processes; recall transcription factors as “master regulators” for expression control.
A 35-year-old pregnant woman undergoes amniocentesis showing an extra chromosome 21 in the fetus. The APRN counsels on risks. Which is the most likely mechanism and associated disease?
A. Polyploidy from complete nondisjunction, leading to Turner syndrome.
B. Structural deletion on an autosome, causing cri du chat syndrome.
C. Aneuploidy via meiotic nondisjunction, resulting in Down syndrome.
D. Mitochondrial DNA aberration, associated with Leigh syndrome.
C. Aneuploidy via meiotic nondisjunction, resulting in Down syndrome.
Full Rationale: The chapter (pages 147-150, implied in outline) covers chromosomes: somatic diploid (46), gametes haploid. Aberrations include aneuploidy (extra/missing chromosome, e.g., trisomy 21 from nondisjunction during meiosis, causing Down syndrome). Polyploidy (A) is multiples (e.g., triploidy 69, lethal); structural (B) like deletions (cri du chat on 5p); mitochondrial (D) is extranuclear, maternal. Maternal age increases nondisjunction risk.
Teaching Points: Trick overcome: Confusing numerical (aneuploidy) with structural—recall aneuploidy affects whole chromosomes. Trap avoidance: Turner is monosomy X (45,X), not polyploidy; link syndromes to specifics (Down = trisomy 21). Pitfall prevention: Mitochondrial is non-chromosomal (chapter exception); always check inheritance (maternal). Strategy: Use karyotype visuals (Fig. 4.12); calculate risks with age (e.g., >35 higher for Down).
A pedigree shows a rare neurologic disorder affecting multiple generations, with equal male/female involvement and no skipping, but one unaffected individual has an affected parent and child. The APRN identifies this as:
A. Autosomal recessive, with consanguinity explaining the pattern.
B. X-linked recessive, due to no male-to-male transmission.
C. Autosomal dominant with incomplete penetrance.
D. Mitochondrial, with maternal transmission only.
C. Autosomal dominant with incomplete penetrance.
autosomal dominant (AD) diseases are rare (<1/500), show vertical transmission, equal sexes, 50% recurrence risk per child (heterozygote parent). Incomplete penetrance (not all with genotype show phenotype) can mimic skipping, but overall no true skips; mitochondrial (D) maternal only.
Trap avoidance: Equal sexes points away from X-linked; chapter notes AD no skips typically. Pitfall prevention: New mutations explain isolated cases (page 18); don’t assume full penetrance.
A couple from a small community presents for preconception counseling. Both are carriers for cystic fibrosis, a disorder with horizontal pedigree pattern and 25% risk per child. The APRN notes increased risk due to:
A. Autosomal dominant pattern with variable expressivity.
B. Consanguinity, increasing likelihood of shared recessive alleles.
C. X-linked inheritance, with the wife as obligate carrier.
D. Incomplete penetrance, reducing actual disease expression.
B. Consanguinity, increasing likelihood of shared recessive alleles.
Full Rationale: PDF search (page 19) describes autosomal recessive (AR): rare, skips generations, horizontal (siblings), increased with consanguinity (shared ancestry uncovers recessives). CF is classic AR, 25% risk if both carriers. AD (A) vertical; X-linked (C) sex-biased; penetrance (D) more AD issue.
Teaching Points: Trick overcome: Horizontal pattern = AR; consanguinity not always present but heightens risk. Trap avoidance: Distractors like A/D confuse with AD features—recall AR needs two copies. Pitfall prevention: Don’t overlink to X-linked without male bias. Strategy: Use pedigrees (chapter examples); screen high-risk populations (e.g., Caucasians for CF).
A pedigree shows hemophilia affecting males across generations, with no male-to-male transmission but affected uncles and grandsons through females. One branch shows a female with mild symptoms. The APRN classifies this as:
A. Autosomal dominant, sex-influenced with higher female expression.
B. X-linked recessive, with the female possibly having skewed X-inactivation.
C. Autosomal recessive, explained by consanguinity.
D. Mitochondrial, due to cytoplasmic inheritance.
B. X-linked recessive, with the female possibly having skewed X-inactivation.
Full Rationale: Chapter outline and PDF (page 23) cover X-linked: more males, no male-male transmission (fathers pass X to daughters). Recessive (XLR) like hemophilia; females carriers, but can show symptoms with skewed inactivation (uneven X silencing). AD sex-influenced (A) like breast cancer (page 23) more females but autosomal; AR (C) equal sexes; mitochondrial (D) all offspring from mom.
Teaching Points: Trick overcome: No male-male = X-linked flag, but check for female involvement (skewed inactivation). Trap avoidance: Sex-influenced (A) is autosomal (e.g., baldness); chapter distinguishes. Pitfall prevention: Mitochondrial all maternal offspring affected. Strategy: Trace transmission: Fathers to daughters only in XLR; practice with pedigrees.
A patient with severe combined immunodeficiency (SCID) is considered for gene therapy. The APRN explains the ex vivo approach, which involves:
A. Direct injection of viral vectors into the body to target cells in vivo.
B. Isolating patient cells, modifying them genetically outside the body, then reinfusing.
C. Using CRISPR to induce frameshift mutations in faulty genes.
D. Predicting drug response based on CYP2D6 polymorphisms for antidepressants.
B. Isolating patient cells, modifying them genetically outside the body, then reinfusing.
Full Rationale: Chapter intro (page 140, Fig. 4.2) describes gene therapy: ex vivo (modify autologous cells outside, reinfuse); in vivo (direct targeting). SCID often ex vivo. A is in vivo; C misuses CRISPR (for correction, not induction); D is pharmacogenomics (Emerging Box, page 143, CYP2D6 for drug metabolism, not therapy).
Teaching Points: Trick overcome: Distinguish ex/in vivo (Fig. 4.2)—ex = “outside.” Trap avoidance: Pharmacogenomics distractor (D) from box; it’s prediction, not therapy. Pitfall prevention: CRISPR for edits, but context is therapy type. Strategy: Link to clinical (ex vivo safer for immune diseases); recall “ex vivo = extract, edit, return.”
Which process results in the synthesis of messenger RNA (mRNA)?
A. Translation at the ribosome
B. Transcription using a DNA template
C. Replication mediated by DNA polymerase
D. RNA splicing in the cytoplasm
B. Transcription using a DNA template
Rationales
* A (Incorrect): Translation produces a polypeptide, not mRNA.
* B (Correct): Transcription uses DNA as a template to synthesize mRNA.
* C (Incorrect): Replication produces DNA, not RNA.
* D (Incorrect): RNA splicing occurs in the nucleus and modifies pre-mRNA; it does not create mRNA de novo.
Which feature distinguishes RNA from DNA?
A. Double-stranded structure
B. Presence of thymine
C. Ribose sugar
D. Ability to undergo replication
C. Ribose sugar
Rationales
* A: RNA is single-stranded.
* B: RNA contains uracil, not thymine.
* C (Correct): RNA contains ribose rather than deoxyribose.
* D: Replication is a DNA function.
The redundancy of the genetic code refers to which concept?
A. Each gene codes for multiple proteins
B. Multiple codons can specify the same amino acid
C. One codon may code for several amino acids
D. Codons vary in length depending on the gene
B. Multiple codons can specify the same amino acid
Rationales
* A: One gene generally codes for one primary protein.
* B (Correct): Redundancy provides protection against some mutations.
* C: Each codon specifies only one amino acid.
* D: Codons are always triplets.
Which enzyme is primarily responsible for DNA replication and proofreading?
A. RNA polymerase
B. DNA ligase
C. DNA polymerase
D. Reverse transcriptase
C. DNA polymerase
Rationales
* A: RNA polymerase is used in transcription.
* B: DNA ligase joins DNA fragments.
* C (Correct): DNA polymerase synthesizes DNA and performs proofreading.
* D: Reverse transcriptase is viral.
Which statement about mutations is correct?
A. Mutations occur frequently during replication
B. Mutations affect all genes equally
C. Mutations are rare events with gene-specific rates
D. Most mutations result in disease
C. Mutations are rare events with gene-specific rates
Rationales
* A: Proofreading limits mutation frequency.
* B: Mutation rates vary among genes.
* C (Correct): This reflects textbook language.
* D: Most mutations are neutral
A normal human somatic cell contains how many chromosomes?
A. 23
B. 46
C. 22
D. 44
B. 46
Rationales
* A: Haploid gametes contain 23.
* B (Correct): Diploid somatic cells have 46 chromosomes.
* C: Autosomes alone number 44.
* D: Does not include sex chromosomes.
Which best describes a karyogram?
A. A genetic sequence map
B. A display of genes on a chromosome
C. An ordered display of chromosomes by size and centromere position
D. A diagram of meiotic crossover
C. An ordered display of chromosomes by size and centromere position
Rationales
* A: Refers to gene mapping.
* B: Describes loci, not karyograms.
* C (Correct): This is the definition used in the text.
* D: Refers to meiosis, not karyotyping.
Which condition represents aneuploidy?
A. Tetraploidy
B. Trisomy 21
C. Euploidy
D. Triploidy
B. Trisomy 21
Rationales
* A: Polyploidy, not aneuploidy.
* B (Correct): Aneuploidy involves extra or missing chromosomes.
* C: Euploidy is normal chromosome number.
* D: Polyploidy is lethal in humans
Why are monosomies typically more severe than trisomies?
A. Monosomies disrupt meiosis
B. Loss of genetic material has greater consequences than duplication
C. Trisomies occur more frequently
D. Monosomies only affect autosomes
B. Loss of genetic material has greater consequences than duplication
Rationales
* A: Severity is not based on meiotic mechanics.
* B (Correct): This is a high-yield textbook principle.
* C: Frequency does not determine severity.
* D: Monosomies can involve sex chromosomes.
Which chromosomal abnormality is most commonly observed in live births?
A. Autosomal monosomy
B. Autosomal trisomy
C. Sex chromosome aneuploidy
D. Polyploidy
C. Sex chromosome aneuploidy
Rationales
* A: Usually lethal.
* B: Less common than sex chromosome aneuploidy.
* C (Correct): Sex chromosome abnormalities are most frequent and less severe.
* D: Lethal.
In autosomal dominant inheritance, which feature is expected?
A. Skipped generations
B. Equal transmission to males and females
C. Only homozygotes affected
D. Parents usually unaffected
B. Equal transmission to males and females
Rationales
* A: Skipped generations suggest recessive inheritance.
* B (Correct): Autosomal traits affect both sexes equally.
* C: Heterozygotes are affected.
* D: Parents are typically affected.
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Ch 0145
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Ch 01 Test Bank13
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Ch 0245
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Ch 02 Test Bank13
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Ch 0371
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Ch 03 Trap Questions25
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Ch 03 New24
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Ch 03 Test Bank39
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Ch 0451
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Ch 04 Test Bank15
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Ch 0520
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Ch 05 Test Bank13
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Ch 0640
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2. Ch 07 Innate Immunity MCQ64
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2. Ch 07 Test Bank46
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2. Ch 08 Adaptive Immunity MCQ62
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2. Ch 08 Test Bank38
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2. Ch 09 Alterations MCQ50
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2. Ch 09 Test Bank41
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Ch 10 Infection MCQ48
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2. Ch 10 Test Bank29
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Ch 11 Stress MCQ57
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2. Ch 11 Test Bank22
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Ch 31 Cardiovascular MCQ0
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2. Ch 31 Test Bank39
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Ch 32 CV Alterations MCQ43
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2. Ch 32 Test Bank43
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Ch 33 Pediatric CV MCQ1
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Ch 33 Test Bank25
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3. Ch 37 Renal MCQ35
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3. Ch 37 Test Questions32
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3. Ch 38 Renal Alterations MCQ24
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3. Ch 38 Renal Alterations Test Bank31
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3. Ch 39 Pediatric Renal MCQ30
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3. Ch 39 Pediatric Renal Test Bank24
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3. Ch 15 Neurologic MCQ30
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3. Ch 15 Test Bank33
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3. Ch 16 Pain & Temperature MCQ29
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3. Ch 16 Test Bank41
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3. Ch 17 Alterations in Cognitive Systems MCQ30
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3. Ch 17 Test Bank44
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3. Ch 18 Brain Alterations MCQ0
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3. Ch 18 Test Bank33
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3. Ch 19 Neurobiology MCQ0
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3. Ch 19 Test Bank19
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3. Ch 20 Pedi Neurologic MCQ0
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3. Ch 20 Test Bank19
