An official website of the United States government
Heterozygous
Heterozygous, as related to genetics, refers to having inherited different versions (alleles) of a genomic marker from each biological parent. Thus, an individual who is heterozygous for a genomic marker has two different versions of that marker. By contrast, an individual who is homozygous for a marker has identical versions of that marker.
Heterozygous. In diploid species, there are two alleles for each trait of genes in each pair of chromosomes, one coming from the father and one from the mother. An allele is one of two or more alternative forms of a gene, and they are found at the same place, or locus, on the chromosome. Heterozygous refers to having different alleles for a particular trait. If the two versions are different, you have a heterozygous genotype for that gene. The relationship between the two alleles affects which traits are expressed.
Amalia Dutra, Ph.D.
Director