Trinucleotide repeat disorders

Question 1

List the 4 trinucleotide repeat disorders

Answer 1

Fragile X Huntington’s Mytonic dystrophy Friedreich ataxia

Question 2

(CTG)n

Answer 2

Myotonic dystrophy

Question 3

(CGG)n

Answer 3

Fragile X

Question 4

Mode of inheritance: Fragile X syndrome

Answer 4

X-linked

Trinucleotide repeat

Question 5

What causes myotonic dystrophy?

Answer 5

Expansion of DMPK1 gene = abnormal expression of myotonin protein kinase

Question 6

(CAG)n

Answer 6

Huntington’s

Question 7

Fragile X syndrome is 2nd most common cause of:

Answer 7

Inherited intellectual disability

(after Downs)

Question 8

Muscle wasting + frontal balding + cataracts + testicular atrophy

Answer 8

Myotonic dystrophy (expansion of CTG in DMPK gene)

Question 9

(GAA)n

Answer 9

Friedrich ataxia

Question 10

Marcoorchidism + long face + large jaw + everted ears + autism + MVP

Answer 10

Fragile X syndrome

(Xtra large ears, balls, jaw)