Allele loss on chromosome 11 in a pituitary tumor from a patient with multiple endocrine neoplasia type 1.

We have examined the allele loss of chromosome 11 in a pituitary tumor from a patient with familial multiple endocrine neoplasia type 1 (MEN 1). The extensive loss of chromosome 11, including loci of D11S149, HRAS1 and F2, was detected by the loss of heterozygosity. All of the lost alleles of these loci were transmitted from the unaffected father and not from an affected mother. This is the first evidence of allele loss of chromosome 11 in a pituitary tumor of MEN 1 and supports the idea that similar allelic deletion of MEN1 locus on chromosome 11 is the common genetic basis for tumorigenesis in the pituitary, endocrine pancreas, and parathyroid gland in MEN 1.