Autosomal recessive:Ageneticconditionthat appears onlyinindividuals who have received two copies of anautosomalgene, one copy from each parent. The gene is on anautosome, a nonsexchromosome. The parents are carriers who have only one copy of the gene and do not exhibit thetraitbecause the gene isrecessiveto its normal counterpart gene.
If both parents are carriers, there is a 25% chance of a child inheriting bothabnormalgenesand, consequently, developing thedisease. There is a 50% chance of a child inheriting only one abnormal gene and of being a carrier, like the parents, and there is a 25% chance of the child inheriting both normal genes.
Cystic fibrosis (CF) is an example of anautosomal recessivedisorder. A CF child has the CF gene on both chromosome 7's and so is said to behomozygousfor CF. The parents each have one CF and one normal paired gene and so are said to beheterozygousfor CF.
Other examples of autosomal recessive disorders include:
- Canavan disease of thebrain
- Congenitalneutropenia, abloodcondition
- Ellis-van Creveld syndrome, abirth defect
- FamilialMediterranean fever with attacks of fever and pain
- Fanconi anemia, aprogressiveblood disorder with a high risk of leukemia
- Gaucher disease (a common genetic disease of Jews
- Mucopolysaccharidosis(MPS), a series ofcarbohydratestorage disorders
- Phenylketonuria (PKU), a disease for which newborns are tested
- Sickle cell disease, the most common genetic disease in Blacks.
