Lynch Syndrome

Question 1

5 steps of MMR process

Answer 1

1. MSH2 notcies strand specificty/there is a mismatch
2. MLH1 cleaves either side of mismatch
3. Helicase unzips+exonuclease removes bad base
4. DNA pol 3 fills in gap
5. ligase

Question 2

Two rep errors recognized by MMR

Answer 2

mismatch and insertion deletion loops

Question 3

Explain microsattelite instability and how associated with DNA MMR defects

Answer 3

Caused by froeward/backward lipase and no MMR, instability may cause translocations and combinations of chroms as well asdletions of key segments of DNA

Question 4

List 2 dna mmr proteinsmost commonly associated with HNPCC

Answer 4

MLH1-methylated (silenced), MSH2

Question 5

what is the function of the two proteins most commonly associated with HNPCC

Answer 5

MLH1 endonuclease activity and MSH2-notice that new strand not same as parental strand

Question 6

Mode of inheritance

Answer 6

Autosomal dominant and epigenetic methylaition of MLH

Question 7

Location

Answer 7

proxmimal prtion of right colon

Question 8

forward.backward slippage

Answer 8

foreward-deltion, backward addition

Question 9

Detect MSI?

Answer 9

PCR and immunobistochemistry

Question 10

Presentation

Answer 10

Cancer before 45, cancer in proxmial colon, pattern of cancer in family