RESUMEN
Bannayan-Riley-Ruvalcaba syndrome (BRRS) is a rare hamartomatous polyposis condition with features of macrocephaly, intestinal juvenile polyposis, developmental delay, lipomas, and pigmentation spots of the male genitalia. An autosomal dominant pattern of inheritance exists in some families, but others appear as sporadic cases. Germ-line mutations in PTEN, a tyrosine phosphatase and putative tumor suppressor gene, have been demonstrated in two families with BRRS, and chromatin loss at the PTEN gene locus on chromosome 10q23 has been demonstrated in two BRRS patients. Germ-line mutations in PTEN have also been described in Cowden disease and in a small number of patients with juvenile polyposis syndrome. In an attempt to assess the nature of PTEN mutations in BRRS, we analyzed three sporadic BRRS patients for chromosome 10q23 deletion or PTEN germ-line mutations. All 3 patients demonstrated no loss of parental alleles at 15 chromosome 10q23 markers that encompassed the region of PTEN. In addition, analysis of mRNA and genomic DNA revealed no nonsense, missense, or insertion/deletion mutations of PTEN. Thus, other mechanisms besides mutation of PTEN must have occurred to cause BRRS in these patients. We speculate that BRRS and juvenile polyposis syndrome may have a heterogeneous etiology to cause their syndromes.
Asunto(s)
Mutación de Línea Germinal/genética , Síndrome de Hamartoma Múltiple/genética , Pólipos Intestinales/genética , Monoéster Fosfórico Hidrolasas , Trastornos de la Pigmentación/genética , Proteínas Tirosina Fosfatasas/genética , Proteínas Supresoras de Tumor , ADN/genética , Discapacidades del Desarrollo/genética , Humanos , Masculino , Fosfohidrolasa PTEN , ARN Mensajero/genética , SíndromeRESUMEN
BACKGROUND & AIMS: Bannayan-Riley-Ruvalcaba syndrome is a congenital syndrome with characteristic features of macrocephaly, cognitive and motor dysfunction, subcutaneous and visceral lipomas and hemangiomas, and intestinal juvenile polyposis. It has been suggested that Bannayan-Riley-Ruvalcaba syndrome may be a variant of juvenile polyposis coli because of the shared features of intestinal juvenile polyps. The aim of this study was to precisely map loss of DNA from 2 patients with intestinal juvenile polyposis and karyotypic abnormalities involving chromosome 10q. METHODS: DNA was extracted from peripheral leukocytes drawn from each patient and each patient's biological parents. The DNA was amplified by polymerase chain reaction using primers specific for microsatellites located on chromosome 10q. RESULTS: Precise mapping localized a maximal distance of 1.0 cM that was commonly deleted from each patient's genome, between D10S541 and D10S1735. This area overlaps the region for Cowden disease, a distinct hamartomatous intestinal polyposis syndrome with increased risk of breast and thyroid carcinoma. CONCLUSIONS: The three hamartomatous polyposis syndromes, Bannayan-Riley-Ruvalcaba syndrome, juvenile polyposis coli, and Cowden disease, may share the same genetic defect because of their common map localization to chromosome 10q23.