Homozygosity

Definition of homozygous genotype
National Cancer Institute

homozygous genotype

(HOH-moh-ZY-gus JEE-noh-tipe)
A term that describes having two identical versions of the same gene (one inherited from the mother and one inherited from the father). In a homozygous genotype, either both genes are normal or both genes have the same mutation (change). For example, a person who inherits the same mutation in both copies of the LDLR gene is homozygous for that gene and will develop a severe form of familial hypercholesterolemia (very high levels of cholesterol in the blood).

Source: NCI Dictionary of Cancer Terms