Skip to content
My WebMD Sign In, Sign Up

Health & Pregnancy

Font Size

Carrier Test for Autosomal Recessive Diseases

h9991037.gif

© Healthwise, Incorporated

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).

Each 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 carrier Both parents are carriers

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.
  • A 50% 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 disease.
  • 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.

ByHealthwise Staff
Primary Medical ReviewerSarah Marshall, MD - Family Medicine
Specialist Medical ReviewerSiobhan M. Dolan, MD, MPH - Reproductive Genetics
Last RevisedNovember 3, 2011

WebMD Medical Reference from Healthwise

Last Updated: November 03, 2011
This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.

Pregnancy Week-By-Week Newsletter

Delivered right to your inbox, get pictures and facts on
what to expect each week of your pregnancy.

Today on WebMD

Woman smiling as she reads pregnancy test
Slideshow
pregnant woman with salad
Quiz
 
pregnancy am i pregnant
Article
calendar and baby buggy
Tool
 

slideshow fetal development
Slideshow
pregnancy first trimester warning signs
Article
 
What Causes Bipolar
Video
Woman trying on dress in store
Slideshow
 

pregnant woman
Article
Close up on eyes of baby breastfeeding
Video
 
healthtool pregnancy calendar
Tool
eddleman prepare your body pregnancy
Video