What is the relationship between genetic testing results and retinoblastoma?

The relationship between genetic testing results and retinoblastoma is nuanced, particularly considering how certain genetic factors can influence the outcomes of tests. In the context of retinoblastoma, which can manifest as familial or sporadic cases, the presence of mosaicism—where a person has a mixture of genetically different cells—can lead to negative results in genetic testing despite the individual being at risk for the condition.

Mosaicism can occur when a mutation arises in a precursor cell during development, meaning that not all cells carry the mutation. Therefore, if a genetic test is performed on a sample that does not capture the affected cells, the result may return negative even though a germline mutation related to retinoblastoma exists. This phenomenon helps explain why someone with a family history of retinoblastoma might not have a detectable mutation in standard testing, thus illustrating the importance of understanding the limitations of genetic testing in certain scenarios.

The other options do not accurately reflect the complexities of retinoblastoma genetics. For instance, a negative test result does not necessarily rule out hereditary risk due to conditions like mosaicism. Moreover, while some cases of retinoblastoma are hereditary, not all cases are, and both bilateral and unilateral cases can be associated with inherited