## **Core Concept**
Familial retinoblastoma is a type of cancer that exhibits a specific pattern of inheritance. It is associated with mutations in the **RB1 gene**, which is a tumor suppressor gene. The inheritance pattern of familial retinoblastoma is characterized by an autosomal dominant mode of transmission.

## **Why the Correct Answer is Right**
The correct answer, , reflects the autosomal dominant inheritance pattern of familial retinoblastoma. This means that a mutation in one of the two copies of the **RB1 gene** is sufficient to increase the risk of developing retinoblastoma. Individuals with a family history of retinoblastoma have a higher risk of developing the disease, and they can pass the mutated gene to their offspring. The autosomal dominant pattern is evident because a single copy of the mutated gene causes the condition, and each child of an affected parent has a 50% chance of inheriting the mutated gene.

## **Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because it does not accurately describe the inheritance pattern of familial retinoblastoma.
* **Option B:** This option is incorrect because it suggests an **autosomal recessive** pattern, which would require mutations in both copies of the gene (one from each parent) to manifest the disease. This is not characteristic of familial retinoblastoma.
* **Option C:** This option is incorrect because it implies an **X-linked** pattern, which is associated with genes located on the X chromosome. Familial retinoblastoma is not linked to the X chromosome.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that individuals with familial retinoblastoma are at increased risk of developing **second primary tumors**, both within and outside the retina. This risk is significantly higher compared to the general population. Therefore, regular screening and monitoring are crucial for early detection and management.

## **Correct Answer:** . Autosomal dominant.