How is huntingtons disease inherited?

Huntington's disease (HD) follows an autosomal dominant inheritance pattern. This means that only one copy of the mutated huntingtin (HTT) gene is sufficient to cause the disease.

Here's how HD is inherited:

* Affected Individual (with HD): An individual with Huntington's disease has two copies of the mutated HTT gene – one inherited from each parent.

* Unaffected Carrier (with one mutated HTT gene): A person who carries one mutated HTT gene and one normal HTT gene is known as an unaffected carrier. They do not develop symptoms of HD themselves, but they can pass the mutated gene to their children.

* Inheritance from Affected Parent: If an affected individual (with two mutated HTT genes) has children, each child has a 50% chance of inheriting the mutated gene and developing HD.

* Inheritance from Unaffected Carrier: When an unaffected carrier (with one mutated HTT gene) has children, there are three possible scenarios for each child:

- 50% chance of inheriting the normal HTT gene and being unaffected.

- 50% chance of inheriting the mutated HTT gene and being an unaffected carrier.

- There is a very small chance of a phenomenon called genetic anticipation. This means that the severity of symptoms and the age of onset can become progressively earlier and more severe in successive generations due to changes in the mutated HTT gene.

It's important to note that HD is a genetic condition, and individuals who do not inherit the mutated HTT gene will not develop the disease. Genetic testing can determine if someone carries the HD mutation or is an unaffected carrier.