RT Journal Article SR Electronic T1 Complex genetic predisposition to cancer in an extended HNPCC family with an ancestral hMLH1 mutation. JF Journal of Medical Genetics JO J Med Genet FD BMJ Publishing Group Ltd SP 636 OP 640 DO 10.1136/jmg.33.8.636 VO 33 IS 8 A1 P Hutter A1 A Couturier A1 R J Scott A1 P Alday A1 C Delozier-Blanchet A1 F Cachat A1 S E Antonarakis A1 F Joris A1 M Gaudin A1 L D'Amato A1 J M Buerstedde YR 1996 UL http://jmg.bmj.com/content/33/8/636.abstract AB Hereditary non-polyposis colorectal cancer (HNPCC) is characterised by a genetic predisposition to develop colorectal cancer at an early age and, to a lesser degree, cancer of the endometrium, ovaries, urinary tract, and organs of the gastrointestinal tract other than the colon. In the majority of families the disease is linked to mutations in one of the two mismatch repair genes, hMSH2 or hMLH1. We have found a novel hMLH1 nonsense mutation in a Swiss family with Lynch syndrome, which has been transmitted through at least nine generations. A different tumour spectrum of neoplasms of the skin, soft palate, breast, duodenum, and pancreas was observed in three branches of this family, where there was a virtual absence of colonic tumours. The hMLH1 mutation could not be detected in members of these branches suggesting that at least a second genetic defect predisposing to cancer is segregating in part of the kindred.