Abstract
Multiple endocrine neoplasia type II (MEN-II or Sipple's syndrome) is an autosomal dominant disorder characterized by medullary thyroid cancers, pheochromocytomas, and parathyroid adenomas. A blind analysis of high resolution G-banded chromosomes was performed on blood specimens from eight MEN-II individuals from three unrelated families and six control subjects. Seven of eight MEN-II patients and one of six control subjects were determined to have a deletion at 20p12.2. These findings support the hypothesis that MEN-II patients have a 20p12.2 deletion (chi 2 = 6.99; p less than 0.01). Genomic DNA from seven of the eight MEN-II patients was studied using the DNA probe, D20S5, localized by in situ hybridization to 20p12. The probe binding site is not deleted in some MEN-II patients, as demonstrated by the presence of two alleles detected as restriction fragment length polymorphisms. Thus, D20S5 does not hybridize to DNA sequences that are deleted based on cytogenetic analysis in MEN-II patients.