Clinical and pathological features of hereditary mixed polyposis syndrome: report on a South African family.
BACKGROUND
Hereditary mixed polyposis syndrome is characterised by multiple large-bowel polyps of differing histological types including a mixture of atypical juvenile polyps, hyperplastic polyps and adenomas. Affected individuals are thought to have an increased risk of malignancy, possibly via the juvenile polyposis pathway.


METHODS
A 51-year-old woman (with a history of a colectomy for polyps during childhood) presented with rectal bleeding. Endoscopy demonstrated small rectal polyps which were hyperplastic on histology. A family tree was drawn up and the three children of the proband underwent flexible sigmoidoscopy.


RESULTS
Endoscopic surveillance of the three children revealed one who had a similar phenotype to the mother. This child underwent colectomy and ileorectal anastomosis. The pathological specimen revealed more than 70 polyps, with a combination of juvenile retention, hyperplastic, adenomatous and inflammatory polyps. A second child had multiple small hyperplastic polyps, and the third had a normal colon. Although the gene locus for the disorder has been mapped, neither the gene nor the disease-causing mutation has been defined.


CONCLUSIONS
A rare inherited polyposis syndrome has been identified in a South African family. Where clinical suspicion of a possible inherited condition exists, investigating at-risk first-degree relatives confirms the inherited nature of the disease. It is possible to use genetic haplotyping (i.e. with a range of markers in the area of the gene) to provide statistical risk to immediate relatives and therefore those at highest risk.
Ibirogba
S B
SB
Colorectal Unit, Department of Surgery, Groote Schuur Hospital and University of Cape Town.
Algar
U
U
Goldberg
P A
PA
Duffield
M
M
Vorster
A
A
Ramesar
R
R
D011125:Adenomatous Polyposis Coli / Q000235:genetics* / Q000473:pathology* / Q000601:surgery; D000328:Adult; D002884:Chromosomes, Human, Pair 15 / Q000235:genetics; D003082:Colectomy; D003106:Colon / Q000473:pathology*; D005260:Female; D005819:Genetic Markers; D006239:Haplotypes; D006801:Humans; D008297:Male; D008875:Middle Aged; D012306:Risk; D013019:South Africa
D005819:Genetic Markers