Biochemistry

Question 1

Cause of Xeroderma Pigmentosum

Answer 1

autosomal recessive enzyme deficiency (an excistion endonuclease) leads to lack of nucleotide excision repair, and thus sensitivity to sunlight because can’t fix pyrimidine (thymine) dimers

Question 2

Cause for Lynch Syndrome (Hereditary nonpolyposis colorectal cancer)

Answer 2

mismatch repair enzymes methylate template strand to differentiate from newly synthesized strand –> defective enzymes result in retention of erros in DNA replication. incomplete penetrance