Huntington's Disease Causes And Diagnosis

Autosomal Dominant Inheritance

The 50/50 chance of a parent with Huntington's disease passing the mutation to their child results from autosomal dominant inheritance. Autosomal genes are contained in the first twenty-two nonsex chromosomes. After conception, the genes of the mother and father mix. Autosomal genes pair up, one from the mother and one from the father. As with other genes, the baby receives one huntingtin gene from the mother and one from the father. If one parent has the mutation in this gene, the child inherits it if the gene is dominant, but escapes Huntington's if it is recessive. The chances of the gene being dominant or recessive are exactly 50/50, regardless of which parent has the disease. As a result, the chances of Huntington's disease being passed down are 50/50 per pregnancy, and it makes no difference whether any siblings inherited the disease or not. In this way, it is like the chances of heads or tails in a series of coin tosses. Each toss has an exactly 50/50 chance of landing heads up. Though clusters of repeated heads or tails tosses may occur, over time, the 50/50 odds prevail.