Pedigree

Question 1

Outline probands

Answer 1

Induvidual affected by a genetic condition or who is concerned they are at risk
Usually the first person in a family who brings the concern of a genetic disorder to the attention of healthcare professionals
(Denoted by an arrow)

Question 2

Outline autosomal dominant inheritance

Answer 2

-50% risk in offspring

Question 3

Outline autosomal recessive inheritance

Answer 3

25% risk in offspring

Question 4

Outline X-linked recessive inheritance

Answer 4

-no male to male transmission as only pass on Y chromosome to son
-males affected almost inclusively
-transmitted through unaffected female carriers

Question 5

Outline Y-linked inheritance

Answer 5

-affect males only

Question 6

Outline mitochondrial inheritance

Answer 6

-conditions can appear in every generation of a family
-females pass on mitochondria but both genders can be affected

Question 7

Outline anticipation as a mechanism

Answer 7

Expansion due to slippage during DNA replication
Above a threshold where the gene stops functioning normally

Question 8

Outline detection of repeats in anticipation

Answer 8

-use PCR with one fluorescent primer and one standard primer
-bind either side of the repeat region
-capillary electrophoresis- exact size (s) of alleles. & number of repeats detected using laser