Mutations in specific DNA mismatch repair (MMR) genes cause Lynch syndrome (often called hereditary non-polyposis colorectal cancer), which is characterized by a predisposition to colorectal cancer and other primary cancers. The colorectal tumours are characterized by an early age of onset and are found predominantly in the proximal colon.


At least four MMR genes are known to cause Lynch syndrome when mutated - MLH1, MSH2, MSH6 and PMS2. Since 1993, hundreds of distinct genomic variants have been identified throughout these genes, and there are few mutation hot spots. A large number of these alterations are missense variants, intronic variants and synonymous changes.


Determining the pathological significance of these variants is difficult; one approach is to review the published literature to determine if others have identified the variant in question and in what clinical circumstances it has been observed. To assist in this process we have catalogued all alterations found in these MMR genes in the literature.


Included in this database are only those variants which have been published in peer-reviewed journals. We have not yet attempted to catalogue variants which have not been published or found on other websites (e.g. InSiGHT). We have provided a means for database users to submit unpublished variants and, in the future, we will include unpublished data in a separate searchable database.


Disclaimer: This database is meant to be a catalogue of known MMR gene variants. We have made no attempt to interpret the pathological significance of these variants. However, during the course of reviewing relevant articles we altered the names of many published variants to reflect the recent recommendations of the HGVS.

There are currently 2499 distinct entries in our database.
Last updated on 07/10/2009

Please use the following citation when referencing this database and website:
M.O. Woods, P. Williams, A. Careen, L. Edwards, S. Bartlett, J. McLaughlin, H. B. Younghusband. (2007). A new variant database for mismatch repair genes associated with Lynch syndrome. Hum. Mut. 28: 669-673.
The MMR Genes Variant Database is not being updated. For the most accurate and up-to-date information on variants in these genes, and other hereditary colon cancer genes, please proceed to the International Society for Gastrointestinal Hereditary Tumours (InSiGHT) database