Genetics Northern California

Autosomal Recessive

The term “autosomal” means that everyone, male or female, has two copies of that particular gene - one from their mother and one from their father.  “Recessive” means that when a change (mutation) is present in BOTH copies of the gene it leads to a genetic disorder or related medical problem. For a recessive condition, there are usually no medical problems as long as one of the two copies is working normally. When both copies of a recessive gene are not working or are working differently than usual, it can lead to medical issues. Autosomal recessive conditions affect males and females in the same way.

How is an autosomal recessive condition inherited?
The parents of an individual with an autosomal recessive condition are both genetic carriers of the condition. Each parent carries one non-working copy of the gene and one working copy. With every pregnancy there is a 1 in 4 or 25% for the child to inherit the non-working copy from both parents and have the recessive condition.

There are rare cases of recessive conditions occurring due to a new mutation in one copy of the gene, along with inheritance of one non-working copy from a parent. In these rare cases, one parent is not a carrier, so other children are not at risk for the same condition. 

Genetic terms that may be used related to an autosomal recessive condition:

  • Carrier: A person who has one working and one non-working copy of a recessive gene is called a carrier. A carrier is able to pass on one genetic mutation that could potentially cause a recessive condition. It is estimated that everyone carries a few non-working recessive genes. But the only time a pregnancy is considered “at-risk” for a recessive condition is when both parents carry a mutation in the same recessive gene.
  • Consanguineous: This means related by blood. Some recessive conditions are so rare that the chance of meeting a partner who carries a mutation in the same recessive gene is extremely low, unless the two individuals are blood relatives (e.g., cousins, second cousins).

Last reviewed: 2/13/15 
Last updated:  2/13/15

Reviewed by: Kaiser Permanent Genetics Department