Association of parathyroid tumors in multiple endocrine neoplasia type 1 with loss of alleles on chromosome 11.

Familial multiple endocrine neoplasia type 1 (MEN-1) is an autosomal dominant disorder characterized by the combined occurrence of tumors of the parathyroid glands, the pancreas, and the pituitary gland. Pancreatic tumors have previously been shown to be associated with the loss of alleles on chromosome 11; we therefore looked for similar genetic alterations in specimens of parathyroid tumors, which are the most common feature of MEN-1. We obtained parathyroid tumors and peripheral-blood leukocytes from six patients with MEN-1; 18 cloned human DNA sequences from chromosome 11 were then used to identify restriction-fragment-length polymorphisms. A loss of heterozygosity was detected in parathyroid tumors from three of the six patients with MEN-1; this finding demonstrated that allelic deletions on chromosome 11 are involved in the monoclonal development of parathyroid tumors in patients with MEN-1. In addition, studies of three affected families (with 17 affected members and 51 unaffected members) established linkage with the oncogene INT2 (peak lod score, 3.30, at 0 percent recombination); the MEN-1 gene was thus mapped to the pericentromeric region of the long arm of chromosome 11 (11q13). Our location of the MEN-1 gene at 11q13 is close to the location previously reported. We conclude that a single inherited locus on chromosome 11, band q13, causes MEN-1 and that the monoclonal development of parathyroid and pancreatic tumors in patients with MEN-1 involves similar allelic deletions on chromosome 11.