Heterozygous Germ Line hCHK2 Mutations in Li-Fraumeni Syndrome

The hCHK2 gene encodes the human homolog of the yeast Cds1 and Rad53 G 2 checkpoint kinases, whose activation in response to DNA damage prevents cellular entry into mitosis. Here, it is shown that heterozygous germ line mutations in hCHK2 occur in Li-Fraumeni syndrome, a highly penetrant familial cancer phenotype usually associated with inherited mutations in the TP53 gene. These observations suggest that hCHK2 is a tumor suppressor gene conferring predisposition to sarcoma, breast cancer, and brain tumors, and they also provide a link between the central role of p53 inactivation in human cancer and the well-defined G 2 checkpoint in yeast.