What causes autosomal disorders?

Autosomal refers to the 22 numbered, non-sex chromosomes in humans. Autosomal traits are passed on from parents to their child. A single abnormal gene on one of the 22 autosomal either parent can cause an autosomal disorder in their child. There are two types of autosomal disorders – dominant and recessive. 

Autosomal dominant disorder 

Autosomal dominant disorder is caused when a child receives an abnormal dominant gene from any one parent. This can happen even if the matching gene from the other parent is normal. In this case, the abnormal gene dominates and only one parent needs to have it to pass it on.

With every pregnancy, there’s a 50% chance that a parent with an autosomal dominant condition will pass it on to their child. Only changes that take place in the DNA of the egg or sperm can be passed on from parents to their children.   

Autosomal recessive disorder 

Autosomal recessive disorder is caused when a child receives an abnormal recessive gene from both parents. In this case, both parents need to pass an abnormal gene to their child for the child to inherit that genetic condition or trait. 

If both parents have an autosomal recessive gene, it will be passed on to about 25% of their children.  One quarter of children will get an autosomal recessive gene if both parents have it. Only changes that take place in the DNA of the egg or sperm can be passed on from parents to their children.