Genetics

Question 1

Heteroplasmy

Answer 1

mitochondria may have different genomes so all not affected by same disorder

Question 2

Characteristics of screening test

Answer 2

high specificity and sensitivity

Question 3

Characteristics of inborn errors of metabolism

Answer 3

• monogenic
• autosomal recessive or X- linked
• few are dominant
• erros based through families

Question 4

Genetic anticipation

Answer 4

• age of onset decreases and severity increases

Question 5

Genetic heterogeneity

Answer 5

1. Same gene, different symptoms e.g CF vs CAVD
2. Same disease, different genes e.g Haemophilia A vs B
3. Same disease, different genes, different inheritance pattern e.g different forms of epidermolysis bullosa may be autosomal dominant or recessive

Question 6

Incomplete penetrance:

Answer 6

symptoms not always present in individual with disease causing mutation

Question 7

Variable expressivity:

Answer 7

severity of disease varies between individuals with same mutation

Question 8

Phenocopy:

Answer 8

same disease but different underlying causes

Question 9

Epistasis:

Answer 9

one gene suppresses action of other nonallelic gene