sentences:  HNPCC is most commonly caused by mutations in hMSH2 and hMLH1, but mutations in hMSH6 are linked to an atypical form of HNPCC.The penetrance of colorectal cancer seems to be lower in these mutations, meaning that a low proportion of hMSH6 mutation carriers present with the disease.Endometrial cancer, on the other hand, seems to be a more important clinical manifestation for female mutation carriers.