Genetics

Question 1

autosomal dominant

Answer 1

males and females affected equally
there are affected individuals in multiple generations
transmission by both sexes and to both sexes

Question 2

autosomal recessive

Answer 2

males and females affected equally
affected individuals usually only in 1 generation
affects siblings
risk when parents are related - consanguineous

Question 3

x-linked recessive

Answer 3

males almost exclusively affected
transmitted through unaffected carrier females
no male-to-male transmission
if father is affected all daughters will be carriers

Question 4

x-linked dominant

Answer 4

males and females affected
often females more often affected
females less severely affected than males
affected males can transmit to daughters but not sons
no male-to-male transmission

Question 5

examples of x-linked dominant conditions

Answer 5

fragile X syndrome
Rett syndrome
Incontentia pigmenti

Question 6

Y-linked inheritance

Answer 6

affects males only
affected males must transmit to their sons
only male-male transmission

Question 7

how to determine pattern of inheritance?

Answer 7

prove it isn’t the others

Question 8

familial hypercholesterolaemia

Answer 8

affects 1/500 in most populations
raised cholesterol from young age - >7.5mmol/L
family history of premature coronary heart disease
mutation of LDL receptor/ APOB
autosomal dominant

Question 9

100% penetrance

Answer 9

all individuals who carry the abnormal gene become affected by the disease

Question 10

reduced penetrance

Answer 10

not all individuals who carry the abnormal gene become affected by the disease

Question 11

how to calculate risk

Answer 11

multiply penetrance by risk of inheritance