Question

In retinoblastoma, the "second-hit" mutation is:

A Always inherited
B Always somatic
C Sometimes somatic
D An activating mutation
E A truncating mutation

Answer 1

The 'second-hit' mutation in retinoblastoma is sometimes a somatic mutation, meaning it is not always inherited but can rather occur spontaneously in a particular cell, leading to the progression of the cancer.

Step-by-step explanation:

In the case of retinoblastoma, a type of cancer that affects the retina, the development of the cancer typically involves a two-hit hypothesis. This hypothesis states that two mutational events must occur in the retinoblastoma gene (Rb gene) for cancer to develop. The first mutation can be either inherited (germline mutation) or occur spontaneously (somatically). The 'second-hit' mutation is not always inherited; rather, it can and often is a somatic mutation. Therefore, the correct answer to the question 'In retinoblastoma, the "second-hit" mutation is:' is C. Sometimes somatic. It is important to note that these mutations usually result in a loss of function of the tumor suppressor gene, allowing cells to proliferate uncontrolled without the usual constraints.