chromosomal disorders

Question 1

Results of Quadruple screen in Down syndrome

Answer 1

• low AFP
• high beta-hCG
• low estriol
• high inhibin A
• put them in alphabetical order then alternate, high, low, high, low

Question 2

Describe the mechanism of the trisomy 21

Answer 2

• maternal nondisjunction of homologous chromosomes during anaphase of meiosis I
• Associated with advanced maternal age
• Mosaicism

Question 3

Edward syndrome is trisomy of what chromosome?

Answer 3

• 18

- Edward has 6 letters and trisomy so 6x3=18

Question 4

Symptoms of Edward syndrome

Answer 4

• Intellecual disability
• Rocker bottom feet
• Micrognathia (undersized jaw)
• clenched hands
• Prominents occiput

Question 5

Describe the Quad screen in Edward syndrome

Answer 5

• Low beta-hCG, AFP and estriol

- normal inhibin A

Question 6

Patua syndrome is trisomy of what

Answer 6

13

Question 7

Clinical symptoms of patau

Answer 7

• Similary to Edward

- Holoprosencephaly, polydactyly, congenial heart disease

Question 8

Pregnancy screening of Patau?

Answer 8

• low beta-hCG

- low PAPP-A

Question 9

Describe the presentation of a double Y male (47,XYY)

Answer 9

• Phenotypically normal
• Tall
• Severe Acne
• Antisocial behavior
• Normal fertility
• Possible associated with autism spectrum disorders

Question 10

What is the chromosomal abnormality in Cri-du-chat syndrome?

Answer 10

-5p deletion

Question 11

Clinical features of Cri-du-chat

Answer 11

• Microcephaly
• moderate to severe intellectual disability
• HIGH-PITCHED CRYING and MEWING
• Epicanthal folds
• Cardiac abnormalities

Question 12

Genetic abnormality in William syndrome

Answer 12

microdeletion of long arm of chromosome 7

Question 13

Clinical features of William syndrome

Answer 13

• Elfin facies, Intellectual disability
• Hypercalcemia due to hypersensitivity to vitamin D
• Good verbal skills, friendliness with strangers
• “Think about Will Ferrel in ELF movie”