Fragile X

Question 1

Fragile X linked to mutation in ____ gene which affects ____ protein

Answer 1

Gene = FMR1
Protein = FMRP

Question 2

Size matters regarding the CGG repeats, how many repeats for:
Typical:
Premutation:
Full mutation:

Answer 2

Typical: 6-44 repeats
Premutation: 55-200 repeats
Full mutation: >200 repeats

Question 3

FMRP is a binding protein that regulates the ____ of proteins and interacts with what ion channel?
hint: transcription or translation

Answer 3

FMRP regulates TRANSLATION of proteins and interacts with K+ channel to decrease the amount of neurotransmitters released.

Question 4

Where can FMRP be found and what would a loss of FMRP cause

Answer 4

It is present at the synapses and represses synaptic proteins. Loss of FMRP = increase in neurotransmitters/synaptic proteins thus increased excitability.

Question 5

Physical phenotype: list 5

Answer 5

1. large ears
2. long narrow face
3. prominent forehead
4. Sensory sensitivities esp.sounds
5. low muscle tone

Question 6

Cognitive phenotype: list 3 weaknesses and 2 strengths

Answer 6

Weaknesses

1. low IQ (mostly 50-60)
2. poor maths skills
3. poor spatial skills

Strengths

1. strong visual memory
2. strong long-term memory
3. . strong language compared to IQ

Question 7

Behavioural phenotype: list 3 weaknesses and 3 strengths

Answer 7

Weaknesses

1. attention problems
2. hyperactivity
3. delayed speech
4. delays in motor skills, esp fine motor skills e.g. feeding, dressing and handwriting.
5. Clumsy

Strengths

1. highly social
2. strong sense of humour
3. good verbal imitation

Question 8

In what way is anxiety different for girls than boys in fragile x?

Answer 8

Girls have higher social anxiety whereas boys have higher anxiety in new situations

Question 9

What two conditions are sometimes co morbid?

Answer 9

30% have ASD (in expression of behavioural phenotypes) and most have ADHD

Question 10

List 3 medical conditions associated with fragile X

Answer 10

1. Seizures = 20%
2. heart issues
3. eye problems
4. ear infections
5. Premature ovarian failure in premutation carriers and late onset neurodegenerative disorder FXTAS

Question 11

Prevalence of Fragile X in boys vs girls

Prevalence of premutation carriers

Answer 11

Fragile X = 1:4500 males, 1:9000 females

Premutation carrier = 1:1000 males, 1:400 females