Genetics

Question 1

describe the genetic inheritance of tuberous sclerosis

Answer 1

AD condition in TSC1 and 2 genes on chromosomes 9 and 16 for tuberin and hamartin which causes inactivation of tumour suppressors

Question 2

presentation of tuberous sclerosis

Answer 2

infantile seizures (cortical tubers)
ash-leaf macule/shagreen patches
periungual fibromas
facial angiofibroma

Question 3

define genetic heterogeneity

Answer 3

mutations in different genes leads to the same phenotype

Question 4

example of a condition that shows genetic heterogeneity

Answer 4

tuberous sclerosis

Question 5

what is activated in neurofibromatosis 1

Answer 5

GDP-Ras pathway

Question 6

presentation of NF1

Answer 6

cafe au lait macules
neurofibromas
axillary or inguinal freckling
optic glioma
Lisch nodules
bony lesions

Question 7

define disease penetrance

Answer 7

how likely people are to show features of the disease

Question 8

define disease expression

Answer 8

different people are affected differently

Question 9

define haploinsufficiency

Answer 9

only one copy of gene is working so half functional protein is made

Question 10

dominant negative

Answer 10

expression of abnormal protein interferes with normal protein

Question 11

define gain of function

Answer 11

mutant protein gains new function affecting cell processes

Question 12

define complete loss of protein

Answer 12

AR- 2 faulty copies of gene produce no protein