A database to support the interpretation of human mismatch repair gene variants

Germline mutations in the mismatch repair (MMR) genes MLH1, MSH2, MSH6, or PMS2 can cause Lynch syndrome. This syndrome, also known as hereditary nonpolyposis colorectal cancer (HNPCC), is an autosomal dominantly-inherited disorder predominantly characterized by colorectal and endometrial cancer. Truncating MMR gene mutations generally offer a clear handle for genetic counseling and allow for presymptomatic testing. In contrast, the clinical implications of most missense mutations and small in-frame deletions detected in patients suspected of having Lynch syndrome are unclear. We have constructed an online database, the Mismatch Repair Gene Unclassified Variants Database (www.mmruv.info), for information on the results of functional assays and other findings that may help in classifying these MMR gene variants. Ideally, such mutations should be clinically classified by a broad expert panel rather than by the individual database curators. In addition, the different MMR gene mutation databases could be interlinked or combined to increase user-friendliness and avoid unnecessary overlap between them. Both activities are presently being organized by the International Society for Gastrointestinal Hereditary Tumours (InSiGHT; www.insight-group.org).