Genetics 7- trinucleotide repeat disorders

Question 1

Trinucleotide repeat disorders show the lhenomenon of

Answer 1

Anticipation

Question 2

Symptoms of the disease are worse and age if presentation of earlier

Answer 2

Anticipation

Question 3

What’s the mechanism behind the repeats in a gene?

Answer 3

Hypermethylation of the cytosine bases creating expansion of the gene beyond stability

Question 4

Give 5 examples of trinucleotide repeat disorders

Answer 4

1. Fridreichs ataxia
2. Huntington disease
3. spinocerebellar ataxia
4. Fragile X syndrome
5. Myotonic Dystrophy

Question 5

Give all their repeats

1. Fridreichs ataxia
2. Huntington disease
3. spinocerebellar ataxia
4. Fragile X syndrome
5. Myotonic Dystrophy

Answer 5

1. GAA
2. CAG
4. CGG
5. CTG

Question 6

Most common mental retardation in males

Answer 6

Fragile X syndrome

Question 7

CGG repeat

Answer 7

Fragile X syndrome

Question 8

More than 200 repeats of CGG cause hypermetilation of cytosine sand silencing of FMR1 gene.

Answer 8

Fragile X syndrome

Question 9

Second most common congenital mental retardation after Down’s syndrome

Answer 9

Fragile X syndrome

Question 10

Short term memory deficits, mild to severe mental retardation, elongated face, maxillary excess, large protruding ears, macroorchidism, mitral valve prolapse (MVP) is most common cardiovascular finding. Repetitive movements such as hand slapping, hypotonia

Answer 10

Fragile X syndrome
Gene FMR1
Repeat CGG