MutL Homolog 1 (MLH1)

MLH1 was identified as a locus frequently mutated in hereditary nonpolyposis colon cancer (HNPCC). It is a human homolog of the E. coli DNA mismatch repair gene mutL, consistent with the characteristic alterations in microsatellite sequences (RER+ phenotype) found in HNPCC. Alternatively spliced transcript variants encoding different isoforms have been described, but their full-length natures have not been determined. The level of expression varied among different samples. All isoforms were found in 43 to 100% of the mononuclear blood cell samples, as well as in other tissues. The authors cautioned that knowledge of existence of multiple alternative splicing events not caused by genomic DNA changes is important for the evaluation of the results of molecular diagnostic tests based on RNA analysis.