Young: Medical Genetics - Extended Matching Questions

Table of Contents

1. Chapter 5
   1. Question 1
   2. Question 2

Question 2

Instructions: Each group of extended matching questions consists of lettered options followed by a list of numbered problems/questions. For each numbered problem/question select the one lettered option that is most closely answers the question. You can use the lettered options once, more than once, or not at all.

Theme: Genes for Mendelian disorders: types of mutations

Options:

1. Point mutation
2. Large frame-shift deletion
3. CGG triplet repeat expansion
4. Small 3 base pair deletion
5. Large in-frame deletion
6. CAG triplet repeat expansion
7. Insertion
8. Inversion

Each of the patients below has a genetic disorder. Select the type of mutation which is most likely to be the cause of his or her disorder.

1

Scenario 1   A 42-year-old man with Becker muscular dystrophy. Choose... Point mutation Large frame-shift deletion CGG triplet repeat expansion Small 3 base pair deletion Large in-frame deletion CAG triplet repeat expansion Insertion Inversion Becker muscular dystrophy (BMD) is caused by mutations in dystrophin, the same gene which causes Duchenne muscular dystrophy. In BMD the mutation is usually an in-frame deletion resulting in production of a truncated but partially functional protein product. Page 111.Incorrect. See Page 111.Your answer has been saved.

2

Scenario 2   A 9-year-old boy with Fragile X syndrome. Choose... Point mutation Large frame-shift deletion CGG triplet repeat expansion Small 3 base pair deletion Large in-frame deletion CAG triplet repeat expansion Insertion Inversion Fragile X syndrome is caused by expansion of a CGG triplet repeat which is much more unstable when transmitted by a female. Page 112.Incorrect. See Page 112.Your answer has been saved.

3

Scenario 3   A 12-year-old girl with cystic fibrosis. Choose... Point mutation Large frame-shift deletion CGG triplet repeat expansion Small 3 base pair deletion Large in-frame deletion CAG triplet repeat expansion Insertion Inversion Approximately 70% of all cystic fibrosis mutations in Western Europe consist of a 3 base pair (single codon) deletion of the 508th residue in CFTR. This mutation is commonly referred to as ΔF508. Page 107.Incorrect. See Page 107.Your answer has been saved.

4

Scenario 4   A 50-year-old woman with Huntington disease. Choose... Point mutation Large frame-shift deletion CGG triplet repeat expansion Small 3 base pair deletion Large in-frame deletion CAG triplet repeat expansion Insertion Inversion Huntington disease is caused by expansion of a CAG triplet repeat in the first exon of the Huntington disease gene. Page 105.Incorrect. See Page 105.Your answer has been saved.

5

Scenario 5   A 5-year-old boy with Duchenne muscular dystrophy. Choose... Point mutation Large frame-shift deletion CGG triplet repeat expansion Small 3 base pair deletion Large in-frame deletion CAG triplet repeat expansion Insertion Inversion Approximately 60% of boys with Duchenne muscular dystrophy have a large frameshift deletion in the gene which encodes dystrophin. Page 111.Incorrect. See Page 111.Your answer has been saved.