Among them, hMLH1-A21V (homolog to Ser16 in S. cerevisiae Mlh2) has been found in Lynch Syndrome patients and is classified as pathogenic, while the hMLH1-E23D mutation (homolog to Ser18 in S. cerevisiae Mlh2) as well as the hMLH1-P309L (homolog to Pro332 in S. cerevisiae Mlh2) have been classified as uncertain. The gene discussed is PMS1; the disease is Lynch syndrome.