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Autosomal recessive

• Overview

Definition:

Autosomal recessive is one of several ways that a trait, disorder, or disease can be passed down through families.

An autosomal recessive disorder means two copies of an abnormal gene must be present in order for the disease or trait to develop.

Alternative Names:

Genetics - autosomal recessive; Inheritance - autosomal recessive

Information:

Inheritance of a specific disease, condition, or trait depends on the type of chromosome affected (autosomal or sex chromosome) whether the trait is is dominant or recessive.

A mutation in a gene on one of the first 22 non-sex chromosomes can lead to an autosomal disorder.

Genes come in pairs. Recessive inheritance means BOTH genes in a pair must be defective to cause disease. If a person only has one defective gene in the pair, they are considered a carrier. However, they can pass the abnormal gene to their children.

CHANCES OF INHERITING A TRAIT

For example, if you are born to parents who both carry the autosomal recessive gene, you have a one in four chance of getting the genes from both parents and developing the disease. You have a 50% chance of inheriting one abnormal gene, which makes you a carrier.

In other words, if four children are born to a couple who both carry the gene (but do not have signs of disease), the STATISTICAL expectation is as follows:

• 1 child is born with 2 normal chromosomes (normal)
• 2 children are born with 1 normal and 1 abnormal chromosome (carriers, without disease)
• 1 child is born with 2 abnormal chromosomes (has the disease)

Note: This does not mean that children WILL necessarily be affected.

See also:

• Autosomal dominant
• Sex-linked dominant
• Sex-linked recessive
• Genetic counseling and prenatal diagnosis
• Heredity and disease

• Review Date: 6/24/2007
• Reviewed By: Chad Haldeman-Englert, MD, Division of Human Genetics, Children's Hospitalof Philadelphia, Philadelphia, PA. Review provided by VeriMed HealthcareNetwork.

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