Chromosomal instability in multiple endocrine neoplasia type 1. Cytogenetic evaluation with DEB test.

Multiple endocrine neoplasia type 1 (MEN 1) is an autosomal dominant condition with high penetrance and variable expressivity, in which tumors or hyperplasia occur in two or more endocrine organs. Some authors have investigated chromosomal instability in MEN 1 and MEN 2; the results are controversial. Chromosome analyses were performed on lymphocytes from seven patients with MEN 1, four healthy first-degree relatives (three of whom were children), six phenotypically normal volunteers, and three patients with Fanconi's anemia. To evaluate chromosomal instability we analyzed phytohemagglutinin-stimulated lymphocyte cultures with and without diepoxibutane. We observed an increase in the frequency of spontaneous chromosomal alterations in four patients. After the DEB test we found an increase in chromatid breakages, gaps, and exchange figures. These findings support the inclusion of the MEN 1 syndrome among the disorders with "chromosomal instability."