What are the chances of your offspring having myopathy if brother has myopathy?

If your brother has myopathy, the chances of your offspring having myopathy depend on the mode of inheritance of the specific type of myopathy that affects your brother. Myopathies can be inherited in different ways, including autosomal dominant, autosomal recessive, and X-linked patterns.

Here's a breakdown of the chances of your offspring having myopathy based on different inheritance patterns:

1. Autosomal Dominant:

- In autosomal dominant myopathies, each affected individual carries one copy of the mutated gene responsible for the condition.

- If your brother has an autosomal dominant myopathy, there is a 50% chance (1 in 2) that each of your offspring will inherit the mutated gene and be affected by the condition.

2. Autosomal Recessive:

- In autosomal recessive myopathies, both copies of the gene responsible for the condition must be mutated for an individual to be affected.

- Carriers have one mutated copy of the gene but are not affected themselves.

- If your brother has an autosomal recessive myopathy, and you are not a carrier of the same mutated gene, the chances of your offspring having myopathy are low. However, if you are also a carrier, the risk of your offspring being affected increases. The exact risk depends on the probability of both you and your brother passing on the mutated gene.

3. X-Linked:

- In X-linked myopathies, the mutated gene is located on the X chromosome.

- Males are more likely to be affected by X-linked myopathies because they have only one X chromosome, while females have two.

- If your brother has an X-linked myopathy, there is a 50% chance that your sons (male offspring) will inherit the mutated gene and be affected. Your daughters (female offspring) have a 50% chance of being carriers, meaning they carry the mutated gene but are not affected themselves.

It's important to note that these chances are based on genetic probabilities and represent averages across a population. Individual cases may vary, and genetic counseling is recommended for accurate risk assessment and personalized information.