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[Frequency and significance of APC gene mutations in malignant degeneration of Barrett esophagus].

The frequency and importance of APC gene mutations in patients with adenocarcinoma in Barrett's esophagus were evaluated. Tissue samples were obtained by endoscopic biopsy or after surgery in 43 patients. DNA analysis was performed with PCR SSCP and DNA sequencing of the mutation cluster region (Exon 15) of the APC gene. Our analysis demonstrated an infrequent occurrence of APC gene mutations in Barrett's cancer (n = 3) and dysplastic Barrett's mucosa (n = 1). Therefore, the functional significance of the frequently observed APC allelic losses (LOH) must be questioned, as a single allelic loss is not sufficient for a complete gene inactivation. It might however be, that a target gene responsible for the molecular pathogenesis of Barrett's cancer is located outside the APC region on chromosome 5q21. 5q allelic losses could however, serve as a marker for the malignant potential of Barrett's epithelium, as they occur with a high frequency in an early stage of carcinogenesis.