Genetic disorders Flashcards
When should screening colonoscopy be started for patients with HNPCC?
20-25 years old or 10 years before the age of the youngest diagnosed relative with CRC
When should a patient with any first degree relative with colorectal cancer begin screening colonoscopy?
age 40 or 10 years before the age of the youngest relative receiving a CRC diagnosis with repeat colo every 5 years if normal
What mode of transmission is HNPCC and what cancers are patients predisposed to?
autosomal dominant; characterized by cancer in the colon, female genital tract, and occasionally other sites; mutation in DNA mismatch repair
Amsterdam criteria for HNPCC:
3 relatives with CRC, over 2 generations, and 1 appearing before age 50
Features of Cowden syndrome:
autosomal dominant mutation of juvenile polyposis syndrome characterized by hamartomatous polyps of colon and associated with breast and thyroid cancer
Autosomal recessive disease associated with mutation in MYH gene and associated with 10 or more synchronous polyps that are predominantly right sided:
Mut Y homolog Associated Polyposis (MAP)
What types of cancer are increased risk with MAP:
CRC, duodenum, ovarian, bladder, thyroid, and skin
mutation and transmission of Peutz Jeghers Syndrome:
germ line mutation in STK11, autosomal dominant
Associated with hamartomatous polyps, mucosal pigmented lesions, and episodes of intussusception from the polyps
Colorectal adenomatous polyposis syndrome with CNS tumors. 2/3 have APC mutation
Turcot syndrome
What mutation and mode of transmission is FAP?
APC mutation; autosomal dominant
Features of Cowden’s disease:
marcocephaly, trichilemmomas, and tumors of thyroid, breast, uterus, and skin with variable types of colon polyps
Most common genetic defect involved in colon cancer:
APC
Genetic mutations of HNPCC:
MLH-1, MSH2, PMS2, MSH6
treatment of HNPCC once colon cancer has occurred:
total proctocolectomy with ileorectal anastomosis
Most common cause of cancer related deaths in patients with FAP who have already had a colectomy
periampullary and duodenal adenocarcinomas
