RESUMEN
This prospective study was designed to identify etiological factors of lower gastrointestinal bleeding and study the [LOH] of NF1 gene in cases of colorectal cancer among the attendants of gastrointestinal tract [GIT] out-patient clinic in El-Minia University hospital in sex months interval. During the period between February and August 2004, [4500] patients presented to the GIT out-patient clinic, Eighty [80] patients of them were complaining of bleeding per rectum. These 80 patients subjected to history taking, clinical examination, abdominal ultrasound, stool analysis, trial of medical treatment and colonoscopy, and study of LOH of NF1 gene in cases of tumours. We found that: 30% of cases of bleeding per rectum showed internal piles, while 10% of patients showed ulcerative colitis and 13.8% showed non specific colitis and 1.3% showed solitary rectal ulcer. Colorectal polyps were found in 11.3% of cases, cancer colon was found in 10% of cases, while normal colonic mucosa was found in 10% of cases. Rectal varices represented 5% of cases, while stenotic lesions represented 1.3% of cases and angiodysplasia represented 1.3% of cases. Juvenile polyps were the commonest colorectal polyps as they were detected in 33.3% of all cases of polyps. Double colonic lesions were detected in 13.8% of cases in our study. LOH was studied in cancer cases and the polyps to detect if it is precancerous or not. Out of the 10% diagnosed as colon cancer, 7% had LOH of NF1 gene while out of 11.3% of the polyp cases only 2% showed LOH. The most common colorectal lesions were internal piles followed by colorectal polyps and inflammatory and ulcerative colonic lesions. A tumor suppressor gene which is NF1 play and important role in cancer development. Screening program for early detection of premalignant and [or] early malignant lesions are highly recommended