Germline mutations in the multiple endocrine neoplasia type 1 gene: Evidence for frequent splicing defects

Multiple endocrine neoplasia type 1 (MEN 1) is a familial cancer syndrome c haracterized by parathyroid hyperplasia, pituitary adenomas, and neuroendoc rine tumors of the pancreas and duodenum. In 1997, the MEN 1 tumor suppress or gene was identified, and numerous germline mutations have been reported to be distributed throughout the gene. We used single strand con formationa l variant (SSCV) analysis to search for germline mutations in the members o f 33 kindreds with a confirmed diagnosis of MEN 1. SSCV analysis revealed 2 5 conformational Variants representing germline mutations that are predicte d to result in loss of normal menin function. Twenty different disease-asso ciated mutations were identified: five resulting in potential abnormal RNA spicing, two missense mutations, seven nonsense mutations, and six frameshi ft mutations. The aberrant splice products were identified and confirmed by RT-PCR and direct sequence analysis for two of the five splice mutations. Sixteen of the 20 (80%) mutations identified have not been previously repor ted. Mutations were not identified in eight kindreds with signs and symptom s consistent with MEN 1, The SSCV analysis revealed mutations in 76% (25 of 33) of the kindreds investigated, thus showing SSCV analysis to be a relia ble mutation detection strategy. One-fifth of the mutations identified in t his study involve intron sequences, therefore, highlighting the importance of including intron sequences in the search for germline mutations in the M EN 1 gene. The need to investigate the entire gene when characterizing new MEN 1 families presents challenges in the translation of genetic studies to efficient clinical diagnostic tests. Hum Mutat 13:175-185, 1999. (C) 1999 Wiley-Liss, Inc.