engleski

Molecular diagnostic of familial adenomatous polyposis in paediatrics

Background: FAP is well-defined inherited autosomal dominant disease with a high penetrance rate, characterized by multiple adenomatous polyps in the colon and rectum. Besides the colonic polyps, patients develop so called extra colonic manifestations, such as polyps in the upper gastrointestinal tract, osteoma, desmoid tumors, epidermoid cysts and congenital hypertrophy of retinal pigment epithelium. Children of affected individuals are at 50% risk of inheriting the disease. For these at risk members of the family, annual endoscopy is recommended because the incidence of the development of cancer in these gene carriers is almost 100%, if no surgical treatment is carried out. Presymptomatic diagnosis of FAP using linkage markers has been the most commonly used method to identify risk individuals in FAP families ; however, the number of families in which an informative test result is found is limited because information on pedigree structure or linkage markers may be inadequate. Identification of APC mutations in FAP families now facilitates the diagnosis of those individuals at a prior 50% risk. Direct analysis of gene alterations may reveal the gene carriers among all the family members. Method: Genomic DNA was isolated from peripheral blood of patients and their relatives (two families). Polymerase chain reaction (PCR) was performed using specific pairs of primers. PCR products were analyzed by electrophoresis on Spreadex EL 300 gels. Results: The genetic analysis confirmed the APC gene codon 1309 germ-line mutation of the APC gene in two children (7- and 9-year-old) not yet having colorectal adenomas, but having inherited APC gene mutation from their mother who died from colon carcinoma aged 35. APC gene mutation analysis also confirmed the diagnosis of FAP in one child, 13-year-old girl having colorectal adenomas as a first case of FAP in that family. Conclusions: Electrophoresis using Spreadex gels provides a simple and rapid method for determination of the most frequent germ-line mutations in the APC gene. We use this method in presymptomatic diagnostics but also to confirm the diagnosis of FAP in the differential diagnostics of the polyposis syndromes. Because FAP patients have a very high risk of colorectal cancer, identification of the individual risk in family members is important to prevent cancer deaths and children detected as a gene mutation carriers can be early included in surveillance program.

FAP; paediatrics; genetics

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