Fragile X

Question 1

What is the genetic basis of FX?

Answer 1

Mutation of fragile X chromosome: CGG repeat expanded in FMR1 gene

Question 2

What is the prevalence for each gender?

Answer 2

1 in 4000 males, 1 in 8000 females

Question 3

What are the differences between the amount of repeats in the X chromosome?

Answer 3

5-40 = typical
55-200 = premutation: 1 in 250 people
200+ = full mutation

Question 4

Why is FX more severe in males?

Answer 4

No secondary X chromosome to rely on

Question 5

What are the physical features of FX?

Answer 5

Large, protruding ears
Long face
Fair hair/skin

Question 6

What are the cognitive features of FX?

Answer 6

Average IQ of 40

Difficulties with attention switching and inhibition

Question 7

Describe the behavioural phenotype.

Answer 7

• Social anxiety/shyness/gaze aversion
• Impulsivity/hyperactivity
• Repetitive speech
• Hand flapping/biting/SIB/compulsive behaviours

Question 8

Are those with FX sociable?

Answer 8

Yes - willing to interact, motivated but also anxious

Question 9

Describe Roberts et al. (2007) findings.

Answer 9

Approach in FX: warm-up effect

- more approaching behaviours by day 2

Question 10

What percentage avert eye-gaze?

Answer 10

children: 83-88%, adults: 98%

Question 11

What percentage of males have social anxiety?

Answer 11

60%

Question 12

What percentage of males have social communication impairments?

Answer 12

30%

Question 13

What percentage of those with FX have autism?

Answer 13

30%

Question 14

What did Moss et al. (2013) describe about ASD in FX?

Answer 14

ASD is a similar pattern of behaviours/deficits, but milder in FX than ASD alone

Question 15

What did Cornish et al. (2007) state about ASD/FX?

Answer 15

Different mechanisms cause similar behaviours in the disorders.
- e.g. eye gaze aversion: social indifference vs social anxiety

Question 16

What were Crawford et al.’s (2015) findings on social processing?

Answer 16

• Face processing with eye tracking: ASD vs FX
• FX spent 1/3 time looking at eye regions: 0.05 v 0.15
• FX look to eye at same speed, but look away quicker
• FX look at faces and bodies = TD, unlike ASD