IHC results were available in 20 of the 29 families; the tumour of 16 probands showed lack of staining (-ve) for MSH6, 2 tumours were -ve MSH2 but positive (+ve) for MSH6, 1 tumour showed isolated loss of MSH6 while 1 was uninformative for MSH6 but +ve for MLH1, MSH2 and PMS2. MSI results were available from 6 probands, all displaying MSI-High (unstable), 4 of them belonging to the -ve MSH6 group. The gene discussed is MLH1; the disease is neoplasm.