Young: Medical Genetics - Extended Matching Questions

Table of Contents

1. Chapter 1
   1. Question 1
   2. Question 2
2. Chapter 2
   1. Question 1
   2. Question 2
3. Chapter 3
   1. Question 1
   2. Question 2
4. Chapter 4
   1. Question 1
   2. Question 2
5. Chapter 5
   1. Question 1
   2. Question 2
6. Chapter 6
   1. Question 1
   2. Question 2
7. Chapter 7
   1. Question 1
   2. Question 2
8. Chapter 8
   1. Question 1
   2. Question 2
9. Chapter 9
   1. Question 1
   2. Question 2
10. Chapter 10
    1. Question 1
    2. Question 2
11. Chapter 11
    1. Question 1
    2. Question 2
12. Chapter 12
    1. Question 1
    2. Question 2
13. Chapter 13
    1. Question 1
    2. Question 2
14. Chapter 14
    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: Mendelian inheritance

Options:

1. Variable expression
2. Reduced penetrance
3. Anticipation
4. Compound heterozygosity
5. Digenic inheritance
6. Uniparental disomy
7. Germline mosaicism
8. Genomic imprinting

Each of the situations below is an example of an unusual genetic feature or mechanism. Select the most appropriate feature or mechanism from the options listed.

1

Scenario 1   Unaffected parents have two children with the autosomal dominant disorder osteogenesis imperfecta, which is known to show complete penetrance. Choose... Variable expression Reduced penetrance Anticipation Compound heterozygosity Digenic inheritance Uniparental disomy Germline mosaicism Genomic imprinting If, as is stated, penetrance is complete, then the only possible explanation, other than non-paternity, is germline mosaicism in one of the parents. See Page 82.Incorrect. See Page 82.Your answer has been saved.

2

Scenario 2   A grandfather, father, and grandson are referred because of an unusual hand malformation which is known to show autosomal dominant inheritance. However, on careful examination only the grandfather and grandson are found to be affected. Choose... Variable expression Reduced penetrance Anticipation Compound heterozygosity Digenic inheritance Uniparental disomy Germline mosaicism Genomic imprinting Complete absence of manifestation represents reduced penetrance, in contrast to different degrees of expression which is referred to as variable expression/expressivity. See Page 72.Incorrect. See Page 72.Your answer has been saved.

3

Scenario 3   A child with cystic fibrosis is found on testing to have inherited different mutations from each parent. Choose... Variable expression Reduced penetrance Anticipation Compound heterozygosity Digenic inheritance Uniparental disomy Germline mosaicism Genomic imprinting Compound heterozygosity (different mutations in homologous alleles) is common in conditions such as cystic fibrosis, for which over 1000 different mutations have been identified. See Page 74.Incorrect. See Page 74.Your answer has been saved.

4

Scenario 4   A child with cystic fibrosis is found to have inherited two copies of its carrier mother's mutation. Choose... Variable expression Reduced penetrance Anticipation Compound heterozygosity Digenic inheritance Uniparental disomy Germline mosaicism Genomic imprinting Uniparental disomy is usually caused by nondisjunction followed by trisomy rescue. A small number of children with autosomal recessive conditions such as cystic fibrosis have been found to have inherited two copies of one parent's mutant allele as a result of uniparental isodisomy. See Page 83.Incorrect. See Page 83.Your answer has been saved.

5

Scenario 5   A family is referred in which an autosomal dominant disorder is showing increasing severity in succeeding generations. Choose... Variable expression Reduced penetrance Anticipation Compound heterozygosity Digenic inheritance Uniparental disomy Germline mosaicism Genomic imprinting Anticipation can manifest as either increasing severity or earlier age of onset in succeeding generations. The explanation usually lies in expansion of a triplet repeat mutation. See Page 81.Incorrect. See Page 81.Your answer has been saved.