8: Fragile X Syndrome

Question 1

Name clinical presentations for fragile X (6).

Answer 1

1. Long and protruding ears
2. Long, thin face with prominent jaw
3. Epicanthal folds
4. High-arched palate
5. Increased head circumference
6. Large testes

Question 2

Normal people have 6-50 FMR1 gene repeats. Carriers have _____. Significantly affected people have _____.

Answer 2

Up to 200.

More than 200.

Question 3

High risk populations for fragile X (3).

Answer 3

1. Children with IDD of unknown etiology.
2. Children with family hx of IDD.
3. Persons diagnosed with autism spectrum disorder.

Question 4

What medications can be used for behavior problems (3)?

Answer 4

1. Ritalin
2. Dexedrine
3. Clonidine

Question 5

What causes the problems in fragile X?

Answer 5

Absence of FMR1 protein production.

Question 6

Do males or females have milder symptoms of fragile X?

Answer 6

Females. Affects both sexes, but females have milder symptoms (likely d/t more than 1 X chromosome).

Question 7

T/F Estimated 1:5,000 are born with fragile X.

Answer 7

True

Question 8

What is the average age of diagnosis (2)?

Answer 8

1. Males: 36 months

2. Females: 42 months

Question 9

The X gene has a unique, _____ expansion.

Answer 9

Trinucleotide. Everyone has FMR1, but when the repeat expansion increases in size, it causes silencing of the gene. This leads to a deficiency or lack of the FMR1 protein.

Question 10

Where is the mutation in fragile X?

Answer 10

Fragile MR 1 (FMR) gene located at Xq27.3

Question 11

Why might females have milder symptoms?

Answer 11

They have 2 X chromosomes.