Numerous cancers are caused by a genetic phenomenon termed "loss of heterozygosity," LOH. This phenomenon led to the identification of genes termed tumor suppressors, because it is the loss of their function that leads to cancer. Which of the following has been shown to result from defects in a tumor suppressor gene as a consequence of LOH?

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Li-Fraumeni syndrome is associated with defects in the tumor suppressor gene TP53, which can result from loss of heterozygosity.  Li-Fraumeni syndrome is a rare inherited form of cancer that involves breast and colon carcinomas, soft tissue sarcomas, osteosarcomas, brain tumors, leukemia, and adrenocortical carcinomas. These tumors develop at an early age in LFS patients. The tumor suppressor gene found responsible for LFS is p53. Mutant forms of p53 are found in approximately 50% of all tumors. The normal p53 protein functions as a transcription factor that can induce either cell cycle arrest or apoptosis (programmed cell death) in response to DNA damage.

Numerous Cancers Are Caused by a Genetic Phenomenon Termed "Loss