Colorectal cancer is the third most common form of cancer in males and the second most common in females [1]. Although the majority of such cases are sporadic, about a quarter of cases may involve some hereditary predisposition. A small proportion are familial, in which a very strong genetic predis­position to develop colorectal cancer is passed on within affected families. Hereditary non polyposis colorectal cancer (HNPCC) and familial adenoma-tous polyposis (FAP) are the most common familial forms of colorectal cancer. A small number of FAP cases involve germline mutations in the MYH gene, and are sub-grouped as MYH-associated polyposie (MAP) [1].

MYH-associated polyposis is caused by germline mutations in the base excision repair (BER) gene MUTYH (MYH) located on chromosome 1p34.3-p32.1, which contains 16 exons. The first descrip­tion of an affected family was reported in 2002 [2]. The phenotype is often indistinguishable from that of an attenuated autosomal dominant FAP caused by mutations in the APC gene, but in MAP, the number of adenomas is often lower (from five to more than 100), and affected patients are often sporadic cases. Two mutational hot-spots have been identified in the MYH gene, p.Tyr165Cys and p.Gly382Asp [3], corresponding to approximately 90% of the muta­tions identified in affected Caucasians [4].

The only mutation reported in two unre­lated Moroccan patients living abroad is the c.1186_1187insGG, p.Glu 396fsX42, within exon 13 [2]. We searched for these three mutations in the MYH gene, in a patient referred to the Department of Medical Genetics in Rabat, Morocco.

Case Report. A 53-year old man, born of non consanguineous healthy parents, was referred to our department for colorectal cancer and genetic coun­seling. His brothers and sisters are healthy and they never showed any digestive problems. His clini­cal history started with asthenia related to anemia, which was accompanied by gastric pain, intermit­tent abdominal colic, and on fibroscopy showed the presence of many polyps. A rectal injection of bar­ium hydroxide in double contrast confirmed multi-ples polyps and showed a suspect nodule in the right colon. Pathological examination found the biopsied polyps to be adenocarcinoma of Duke. Some 80 from whole blood by standard methods, and the two exons 7 and 13 were amplified by poly-merase chain reaction (PCR) and sequenced on an ABI PRISM™ 310 genetic analyzer (Applied Biosystems, Foster City, CA, USA) to detect the p.Tyr165Cys, p.Gly382Asp and c.1186_1187insGG MYH mutations. Any mutation was confirmed on a second independent DNA sample.