52. Lynch syndrome

Question 1

Lynch syndrome is AKA

Answer 1

Hereditary non polyposis colorectal cancer ( HNPCC)

Question 2

Lynch syndrome - definition/ mode of inheritance/ course

Answer 2

AD mutation of DNA mismatch repair genes with subsewuent microsattelite instability –> 80% progress to CRC ( proximal colon in always involved)

Question 3

lynsch syndrome - cancers ?

Answer 3

1. Colorectal ( de novo, not from adenatous polyp)
2. ovarian
3. endometrial
4. skin

Question 4

• A woman is diagnosed with endometrial cancer and has multiple relatives with skin and colorectal cancer. What syndrome do you suspect?

Answer 4

Lynch syndrome, or HNPCC (requires 3 relatives with Lynch syndrome across 2 generations, at least 1 found before age 50)

Question 5

• Hereditary nonpolyposis colon cancer, or Lynch syndrome, involves mutations of DNA ____ genes. It is of autosomal ____ inheritance.

Answer 5

Mismatch repair; dominant

Question 6

• If working up a patient for HNPCC, what part of the bowel do you biopsy? What gene mutation would you look for in the biopsied tissue?

Answer 6

The proximal colon (is always involved); screen for mutations of DNA mismatch repair genes with subsequent microsatellite instability

Question 7

• What percentage of patients with HYPNCC will progress to have colorectal cancer?

Answer 7

Approximately 80%