autosomal-recessive inheritance

autosomal-recessive inheritance,

a pattern of inheritance resulting from the transmission of a recessive allele on an autosome. Males and females are usually affected with equal frequency. If both parents are heterozygous (Aa), each of their children has a 25% chance of expressing the trait of the recessive allele. If both parents are homozygous recessive (aa), all of the children will express the trait. If one parent is homozygous recessive and the other is homozygous dominant (AA), none of the children will express the trait, but all will be carriers (Aa). There may be no family history of the trait; it becomes manifest when two carriers have a child who is homozygous recessive. Cystic fibrosis, phenylketonuria, and galactosemia are examples of traits that result from autosomal-recessive inheritance. Compare autosomal-dominant inheritance. See also recessive.