Multiple endocrine neoplasia type 1 (MEN 1) is an autosomal dominantly inherited syndrome, characterized by the combined occurrence of tumors of the parathyroid glands, endocrine pancreas, and anterior pituitary gland.
The MENIN gene, which is a kind of tumor suppressor gene, is located at the chromosomal locus 11q13. It consists of one untranslated exon and nine exons encoding the menin protein.
We report a case of a 22-yearss-old woman with MEN type 1, who was proven to have a mutation in the MENIN gene. The patient was admitted because of repeated hypoglycemia. The fasting plasma glucose level was 32 mg/dL. Seventy two hours fasting test showed an the insulin/glucose ratio as 0.33. Endoscopic ultrasonography detected multiple masses on the pancreas. The arterial-stimulated venous sampling (ASVS) with calcium showed sudden step up of insulin at the head and tail portions of the pancreas. The sellar MRI showed a pituitary mass that produced prolactin. Instead of a pathologic diagnosis from operational specimen, the genetic analysis revealed a mutation in the MENIN 1 gene (exon 2, 200~201insAGCCC).