Familial adenomatous polyposisFeb 3, 2020
Familial adenomatous polyposis (SAP) is a hereditary disease in which multiple formations develop on the mucous membrane of the colon, in another way – polyps. In most cases, there are no clinical symptoms, and the diagnosis is a "random finding" during routine examinations. This condition requires constant monitoring, since without appropriate treatment, it leads to the development of a malignant tumor of the colon at the age of 40 years. The incidence is 1 in 8,000-14,000 people.
Polyps are detected by the age of 15 in 50% of patients, and by the age of 35-in 95%. This rare genetic disease is based on chromosomal rearrangements in the long arm of the 5th chromosome, affecting the APC gene (the gene for adenomatous polyposis of the colon), both in tumor cells (non-inherited mutation) and in normal cells (hereditary mutation), which leads to the loss of suppressor genes that prevent tumor cell transformation.
SAP is a disease with an autosomal dominant type of inheritance, that is, the disease will manifest itself in each next generation. With GLANDERS in the colon and rectum, ≥ 100 adenomatous polyps growing on the surface of the intestine are detected. If > 100 polyps are detected during colonoscopy (i.e., the doctor evaluates the condition of the inner surface of the colon with an endoscope), patients, as well as their relatives of the 1st degree of kinship, should undergo genetic testing to detect a specific mutation. If genetic testing is not possible, it is necessary to screen and examine the patient's relatives annually, starting from the age of 12, by sigmoscopy-examination of the rectal mucosa; the frequency of screening examinations decreases with each decade. The probability of developing adenomatous polyposis of the colon in children of patients by the age of 35 is 50%, so they need an annual rectoromanoscopy. Polyps are usually evenly distributed throughout the colon from the blind to the anal canal, which makes it impractical to perform more burdensome and expensive procedures (colonoscopy and irrigoscopy). If control over the course of the polyps is not possible, or if the colon and rectum are not removed, the probability of developing colon cancer by the age of 70 is estimated to be 80%.
Clinically, the disease is most often asymptomatic - there may be hidden blood loss with feces, but there may also be various extra-intestinal formations of both benign and malignant nature (Gardner's syndrome).
Patients also have an increased risk of duodenal cancer (5-11%), pancreatic cancer (2%), thyroid cancer (2%), brain tumors (medulloblastoma with a frequency of < 1%), liver cancer (and hepatoblastoma-malignant tumors that develop in childhood, with a frequency of 0.7% in children aged
Timely genetic diagnostics can identify the "invisible killer", prevent the development of many dangerous pathologies and prolong the life of the patient, as well as help determine the tactics of actions for his relatives.
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