Hereditary adenomatosis of the colon and rectum: clinical features of eight families from northern Italy.

Adenomatosis coli (or familial polyposis of the large bowel) and related syndromes are relatively rare diseases characterized by an autosomal dominant mode of inheritance. In these diseases, the entire colorectal mucosa is covered by hundreds (often innumerable) polyps of various dimensions. In addition, several extracolonic abnormalities have been reported. In the present study, we describe the clinical features of eight families from northern Italy fulfilling the diagnostic criteria of adenomatosis coli. Information was available on 123 unaffected and 30 affected family members. The most relevant findings of the study can be summarized as follows. 1) Gene frequency was calculated to be between 1:7,300 and 1:19,000. Segregation ratio in affected branches was 0.57, with a gene penetrance of nearly 60% and a male:female ratio of 1.73. 2) Extracolonic manifestations were present in all families and in 15 of 30 affected patients, the most frequent being cutaneous cysts and retinal lesions. No case fulfilling the classical criteria of Gardner syndrome was observed. 3) When the diagnosis of adenomatosis followed the appearance of symptoms, colorectal cancer had usually already developed, whereas no malignant changes were observed in individuals diagnosed in the asymptomatic stage. When colectomy with ileorectal anastomosis was the treatment of choice, polyps tended to recur in the rectal stump, and long-term endoscopic follow-up was necessary. In conclusion, adenomatosis coli may account for a definite proportion of colorectal neoplasms observed in the general population. Taking into consideration the genetic base of the disease, it follows that individuals at risk should be closely monitored for several years. Moreover, clinical investigations should not be limited to the large bowel, but should be extended to the skin, upper digestive tract, fundus oculi, bones, and probably other organs.