Genetics

Question 1

What is the most common cause of Trisomy 21?

Answer 1

Non dysjunction during meiosis which is usually related to maternal age

Question 2

Which chromosome if the robertsonian translocation trisomy 21 usually attached to?

Answer 2

Chromosome 14

Question 3

Which chromosome is affected in Edwards syndrome and name 3 features

Answer 3

Trisomy 18. Rockerbottom feet, cardiac and renal problems, prominent occiput and flexed overlapping fingers

Question 4

Which chromosome is affected in Patua syndrome and name 3 features

Answer 4

Trisomy 13. Structural defects of the brain, eye defects, cleft lip and palate, polydactyly

Question 5

What chromsome is affected in cri du chat syndrome and name 3 features?

Answer 5

Deletion of the tip of the short arm of chromosome 5. High pitched mewing cry, microcephaly, developmental delay

Question 6

Which chromosome is affected in DiGeorge syndrome and name 3 features?

Answer 6

Microdeletion of chromosome 22q11. Congenital heart defects, thymic hypoplasia causing immunodeficiency, hypocalcemia secondary to hypoparathyroidism

Question 7

Which chromosome is affected in Williams syndrome and name 3 features?

Answer 7

Microdeletion of chromosome 7q11. Loss of elastin gene causes heart valve abnormalities, very friendly social personality

Question 8

What is the trinucleotide repeat sequence for Huntingtons?

Answer 8

CAG, autosomal dominant

Question 9

What is the trinucleotide repeat sequence for Fragile X?

Answer 9

CGG, X linked dominant

Question 10

What is the trinucleotide repeat sequence for myotonic dystrophy?

Answer 10

CTG. autosomal dominant

Question 11

What is the trinucleotide repeat sequence for Frederichs ataxia?

Answer 11

GAA, autosomal recessive

Question 12

What is the difference between Angelman and Prader Willi syndrome?

Answer 12

If the deletion occurs on chromosome 15 inherited from DAD = Prader Willi syndrome, if chromosome 15 deletion if inherited from MOM = Angelman syndrome

Question 13

What type of inheritance is hereditary spherocytosis?

Answer 13

autosomal dominant

Question 14

What type of inheritance is achodroplasia (dwarfism?)

Answer 14

autosomal dominant

Question 15

What are classic clinical features of Beckwith Weidmann syndrome?

Answer 15

Macroglossia, Gigantism, Hypoglycemia, Ompahlocoele

Question 16

What is the mode of inheritance for duchenne muscular dystrophy? What is the first screening test?

Answer 16

X linked recessive. Screening test- CK - will be grossly elevated

Question 17

What should be considered in any female patients presenting with an inguinal hernia?

Answer 17

Complete androgen insensitivity syndrome where phenotype 46XY can present with female genitalia

Question 18

Name two characteristics of fetal alcohol syndrome

Answer 18

Smooth philtrum and thin upper lip

Question 19

What chromosome is affected in neurofibromatosis type 1 and what type of inheritance pattern is it?

Answer 19

Chromosome 17 and autosomal dominant

Question 20

How many out of 7 does a clinical diagnosis of neurofibromatosis need to have?

Answer 20

2 out of 7. Genetic testing is not routinely advocated

Question 21

What genetic condition might you see lens dislocation and what type of inheritance is it?

Answer 21

Marfan syndrome- autosomal dominant

Question 22

What are some features of Fanconis anaemia and what inheritance is it?

Answer 22

Autosomal recessive, aplastic anaemia, sensorinueral defects, short statutre, skeletal abnormalities

Question 23

What inheritance pattern is sickle cell disease?

Answer 23

Autosomal recessive

Question 24

What does the newborn blood spot screen for?

Answer 24

6 metabolic diseases, cystic fibrosis, sickle cell disease, congenital hypothyroidism

Question 25

Name a limitation of array CGH

Answer 25

Can identify microdeletions and microduplications but cannot identify deletions or expansions in a single gene

Question 26

What is thrombocytopenia with absent radii and the inheritance pattern?

Answer 26

Missing radius bone but otherwise normal upper limbs, thrombocytopenia. Autosomal recessive

Question 27

What is Bloom syndrome and describe three features

Answer 27

Defect in DNA repair mechanisms- short stature, photosensitivity and telangetasia on the face

Question 28

Usually what type of inheritance pattern is Ehler Danlos?

Answer 28

Autosomal dominant

Question 29

Name a condition that causes reduced AFP

Answer 29

Trisomy 21, 18 and 13 and turner syndrome

Question 30

What is the triad normally seen in Pierre Robin syndrome?

Answer 30

microganthia (small jaw), glossoptosis, cleft palate

Question 31

Name three features of albright hereditary osteodystrophy

Answer 31

Short stature, obesity, shortening of the fourth & fifth metacarpals

Question 32

What inheritance pattern is cystic fibrosis?

Answer 32

Autosomal recessive

Question 33

What inheritance pattern is haemophilia A

Answer 33

Autosomal recessive

Question 34

What inheritance pattern is hereditary spherocytosis?

Answer 34

Autosomal dominant

Question 35

What is rapid aneuploidy screen?

Answer 35

Quick way of counting the number of Chromosomes 13, 18, 21 and the sex chromosomes. Result is usually in 24-48 hours compared to full karyotyping