heterozygous /het′ərəzī″gəs/ [Gk, heteros + zygotos, yoked] , having two different alleles at corresponding loci on homologous chromosomes. An individual who is heterozygous for a trait has inherited an allele for that trait from one parent and an alternative allele from the other parent. An individual who is heterozygous for a genetic disease caused by a dominant allele, such as Huntington’s disease, manifests the disorder. A person who is heterozygous for a hereditary disorder produced by a recessive allele, such as sickle cell anemia, is asymptomatic or exhibits reduced symptoms of the disease. The offspring of a heterozygous carrier of a genetic disorder have a 50% chance of inheriting the allele associated with the disorder if the other parent does not carry the allele. Compare homozygous.
