TP53 and Li-Fraumeni syndrome: LOH has been observed to be evident in fewer than one-half (44%) of the 36 tumors formed in 28 Li-Fraumeni syndrome (LFS) or Li-Fraumeni-like (LFL) patients who harbor germline mutations of the p53 gene (two prominent mutant codons encode R273H and R175H in humans) [28].