Loss of heterozygosity (LOH) is a genetic event that results in the loss of one parent's contribution to the cellular DNA. It often occurs in regions of chromosomes that harbor tumor suppressor genes, which are crucial in preventing uncontrolled cell growth. When an individual has a mutation in one allele of a tumor suppressor gene, the other allele usually compensates. However, if the wild-type allele is lost, the cell is left with a defective gene, which may lead to cancer development.
