MLPA-based LOH analyses. A: The MSH2/MLH1-MLPA analysis profile of healthy control DNA. B: germline del5-6 MLH1 (SK-22 patient). C: SK-22 tumor, homozygous del5-6 of MLH1 indicating LOH at LGR. D: SK-14 germline, MSH2 del1-7. E: SK-14 tumor, retention of heterozygosity at LGR region. F: SK-20 germline, dup5-6 MSH2. G: SK-20 tumor, retention of heterozygosity at LGR region. Arrows, deleted/duplicated exons; asterisk, LOH.