Hereditary mixed polyposis syndrome: (HMPS) A cancer family syndrome characterized by the development of a variety of different types of polyps in the colon, including atypical juvenile polyps and adenomas of the colon, and by the development of colorectal carcinoma (cancer of colon and rectum). HMPS is inherited in an autosomal dominant manner. The HMPS gene locus is on chromosome 15 in region 15q13-q14. HMPS is also known as colorectal adenoma and carcinoma 1 (CRAC1).
It has been uncertain whether HMPS is a distinct disorder or a variant of an established disease called juvenile polyposis. The odds currently appear in favor of it being either a distinct disorder or a genetically distinct form of juvenile polyposis since the genes known to cause juvenile polyposis are in chromosomes 10q22.3 and 18q21.1.