hereditary colorectal pathologies Flashcards
incidence of FAP
1% population
1.8 new patients per million
inheritance of fap
autosomal dominant
what is the mutation for fap
APC gene 5q21 adenomatous polyposis coli gene -tumour suppressor gene
what does APC protein do
binds to beta catenin and prevents it translocating to the nucleus and upregulating expression
extra-intestinal features of fap
- Duodenal polyps occur in 100% of patients If long enough
- Gastric fundal polyps in 50%
- Skull osteomas seen in gardners syndrome
Congenital hypertrophy of the retinal pigment epithelium - Epidermoid cyst
- Desmoid tumours- arise in mesentry or on abdominal wall that are benign but become large and obstruct- give tamoxifen
what is hnpc also known as
Lynch syndrome
what is the criteria for hnpcc
Amsterdam criteria
>3 family members with histologicall proven cc
-one relative being a 1st degree relative of the other2
->2 generations affected
-age at onset <50 in at least 1 family member
-uterine cancer in 1 or more relatives acceptable as part of 3 member family
what is hnpcc
mutation in DNA mismatch repair gene
life time risk of cancer for hnpcc m and f
80% males
30% females
inheritance of hnpcc
autosomal dominant
what is microsatellite instability
defect in MLH1 promoter
- accumulate lots of replication errors
- repetitive DNA eg CAT
types of mutations
- missense: replace 1 base pair=different protein made
- nonsense: brings protein to an end
- insertion/ deletion and duplication
- frameshift: protein is non functional from above types
- repeat expansion: nucleotide repeats that can increase the number of times repeated
what is Hirschsprung disease
disease in which the Meissner and Auerbach plexus in certain segments of the bowel are missing from birth
treatment hirschsprung
take out aganglionic segment
what is pyloric stenosis
born with narrowed pylorus so cut it
where is the mutation in peutz jegher
mutation in STK11 gene which is a tumour suppressor gene
what types of polyps do you get in peutz jegher
Haemartomatous
inheritance of pj
autosomal dominant
what is MAP
MUTYH associated polyposis
MAP inheritance
Autosomal recessive
treatment of MAP
Once identified resection and ileoanal pouch reconstruction is recommended
screening for FAP
Annual flexible sigmoidoscopy from 15 years
If no polyps found then 5 yearly colonoscopy started at age 20
screening for hnpcc
Colonoscopy every 1-2 years from age 25
