A novel deletion of the MEN1 gene in a large family of multiple endocrine neoplasia type 1 (MEN1) with aggressive phenotype.

Context: The MEN1 syndrome is associated with parathyroid, pancreatic and pituitary tumours and is caused by mutations in the MEN1 gene. In general, there is no genotype-phenotype correlation.

Objectives: To characterize a large family with MEN1 with aggressive tumour behaviour: malignant pancreatic endocrine tumours were present in five affected subjects and were the presenting features in three subjects.