Sporadic follicular thyroid tumors show loss of a 200-kb region in 11q13 without evidence for mutations in the MEN1 gene.

Loss of heterozygosity (LOH) in 11q13 where the tumor suppressor gene for multiple endocrine neoplasia type 1 (MEN 1) is located has been demonstrated in several tumor types, including follicular thyroid tumors, but whether the MEN1 gene is actually involved in their tumorigenesis is not known. In the present study, the involvement of the MEN1 gene in follicular thyroid tumors was investigated. By using 14 MEN1-linked microsatellite markers, LOH was demonstrated in 12 out of 60 follicular thyroid tumors: 2/18 adenomas, 4/15 atypical adenomas, 1/6 Hürthle cell adenomas, 1/9 carcinomas, 3/6 Hürthle cell carcinomas, and 1/6 anaplastic carcinomas. In the tumors with LOH, a single minimal region of overlapping deletions was mapped to the 200-kb interval between D11S4946 and D11S4939. Tumors that showed 11q13 LOH were screened for mutations of the MEN1 gene using single-strand conformation analysis. Abnormal shifts detected in seven tumors in two exons were sequenced, which revealed two different polymorphisms present in both tumor and constitutional DNA, but without somatic mutation. Taken together, these results suggest that in this region, a tumor suppressor gene other than MEN1 might be involved in the tumorigenesis of follicular thyroid tumors. Genes Chromosomes Cancer 26:35-39, 1999.