What is the primary effect of loss of function mutations in cancer?

Loss of function mutations in cancer primarily lead to the inactivation of protein functions. These mutations typically affect tumor suppressor genes, which are critical for controlling cell growth and preventing tumor formation. When a loss of function mutation occurs, the normal regulatory mechanisms provided by these proteins are disrupted.

For example, if a mutation in a tumor suppressor gene like TP53 occurs, the resulting protein may be unable to properly regulate the cell cycle or initiate apoptosis (programmed cell death) in the presence of DNA damage. This inactivation contributes to uncontrolled cell proliferation and tumor progression, which is a hallmark of cancer.

Understanding this mechanism highlights the importance of tumor suppressor genes in maintaining cellular integrity and how their dysfunction can lead to malignancy. Enhanced or normal protein functions, lack of impact, or increased production of proteins do not correctly represent the consequences of these mutations in the context of cancer pathology.