Final answer:
An individual with an inherited cancerous mutation in a tumor suppressor gene is most likely to be heterozygous. This is due to the two-hit hypothesis where both alleles must be altered for cancer to develop. Homozygous conditions for tumor suppressor genes are rare and often not viable. A. Heterozygous
Step-by-step explanation:
Understanding Genotypes in Hereditary Cancer
If an individual inherits a cancerous mutation in a tumor suppressor gene, the most likely scenario is that the individual is heterozygous for the mutation. This means they carry one mutated allele and one normal allele. Tumor suppressor genes usually adhere to a genetic principle called the two-hit hypothesis, where both alleles of a tumor suppressor gene must be altered or 'hit' to knock out function. When someone is born with one defective allele, as in the case with inherited mutations such as those in BRCA1 or BRCA2, there's a higher likelihood for the second 'hit' to occur, leading to cancer.
The option C, homozygous, typically does not apply to tumor suppressor genes in hereditary cancers because having two mutant alleles from the start would likely result in an early onset of cancer, possibly even in utero, and might be incompatible with life. Therefore, most inherited mutations related to tumor suppressors present as heterozygous conditions, with the individual having a greatly increased risk of cancer if the second allele becomes mutated.
As mentioned, hereditary cancers often arise due to defective tumor suppressor alleles present in the germline mutations. These mutations increase the possibility of cancer development, as they may impair crucial DNA repair processes when activated or 'switched off'. It is important to note that the presence of a heterozygous genotype does not guarantee cancer but signifies an elevated risk as compared to individuals without such mutations.