[Clinical and genetic features of APC- and MYH-mutation-negative patients with multiple polyposis of large bowel that tested by conventional methods].

The genealogic analysis, molecular and clinical investigations has been carried out in 19 probands with multiple colorectal adenomas (approximately 100 or more). Twelve of these patients (63.1%) were APC and MYH mutation-negative. Three (25%) probands have positive family history. The median of the disease manifestation age in APC-negative patients was intermediate between the median of the disease manifestation age in APC- and MYH-positive patients. Extraintestinal manifestations in the APC-negative probands are more rare than in APC-positive patients. A half of APC- and MYH-negative probands with multiple polyposis had colorectal cancer. APC- and MYH-negative patients formed a genetically heterogenous group.