Tumor MLH1 methylation was detected in 23 tumors from 22 SLS cases where the concordance between the two internal assays was 100% and, in all but one of the tumors, there was loss of expression of MLH1 protein by IHC (a single MLH1 methylation positive tumor SLS005 showed solitary loss of PMS2). The gene discussed is MLH1; the disease is neoplasm.