Fergus - Example Questions

Question 1

Write a note on Fragile X Syndrome
(6)

Answer 1

Trinucleotide (CGG) repeat on the 5’ untranslated region

Between 50 and 200 repeats

Exactly 170 or 200+ repeats results in methylation of promoter and failure of FMR1 gene

Mutation in FMR1 gene

RNA binding protein associated with polyribosomes

Fragile site at Xq27

Affects 1/2000 males

Question 2

Write a note on Cystic Fibrosis
(4)

Answer 2

Cystic Fibrosis Transmembrane conductance regulator gene found on chromosome 7

80% have small deletion delta F 508 mutation on exon 10

Deletion of last G of 507 isoleucine and first and second T of phenylalanine -> results in ATT = stop codon and loss of phenylalanine

1/19 people have it in Ireland

Question 3

Write a note on Duchenne muscular dystrophy
(9)

Answer 3

DMD - duchenne muscular dystrophy gene/dystrophin gene

Largest known gene -> makes dystrophin protein

79 exons -> 60% of mutation involve the deletion of at least one exon

Deletion on 5’ end from promoter to exon 19

Deletion on 3’ end from exon 40 to 79

Detected using a multiplex PCR (5’ and 3’ multiplex)

Two types: Duchenne and Becker

Affects 1 in 3500 male births

Causes severe muscle wasting

Question 4

How many people does DMD affect?

Answer 4

1 in 3500 males

Question 5

How do you diagnose DMD?

Answer 5

5’ and 3’ multiplex PCR