Autosomal recessive diseases are genetic diseases that are passed to a
child through both parents' chromosomes. Autosomal recessive diseases include
Tay-Sachs disease, cystic fibrosis, sickle cell anemia, autosomal recessive
polycystic kidney disease (ARPKD), and phenylketonuria (PKU).
person inherits 23 chromosomes from each parent and so has 23 pairs of
chromosomes. Each chromosome contains genes. One or both of the chromosomes in
a pair can carry a mutation and be abnormal or defective in a way that causes a
genetic disease. In an autosomal recessive disease, both chromosomes in a pair
must have a defective gene for the person to have the disease. If only one gene
is defective, the person is a carrier of the disease but
does not have any symptoms.
Carrier test information for autosomal recessive diseases
One parent is a
Both parents are
If only one parent
carries the abnormal gene, there is:
A 50% chance in each pregnancy that their
child will receive the defective gene and be a carrier.
chance in each pregnancy that their child will not receive the defective gene
and will not be a carrier or have the disease.
Almost no chance that
their child will have the disease.
If both parents carry
the abnormal gene, there is:
A 25% chance in each pregnancy that their
child will inherit the defective gene from each parent (two genes) and have the
A 50% chance in each pregnancy that their child will
receive one defective gene and be a carrier.
A 25% chance in each
pregnancy that their child will not receive the defective gene and will not be
a carrier or have the disease.
Primary Medical Reviewer
Kathleen Romito, MD - Family Medicine
Specialist Medical Reviewer
Siobhan M. Dolan, MD, MPH - Reproductive Genetics
Current as of
March 12, 2014
WebMD Medical Reference from Healthwise
March 12, 2014
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