kodomináns

Codominance is a form of genetic inheritance in which both alleles at a gene locus are expressed in the phenotype of the heterozygote. In this pattern, neither allele completely hides the other, and the resulting trait shows contributions from both alleles rather than a blended or single-acting effect.

Classic examples include the ABO blood group system, where the IA and IB alleles are codominant with respect to each other: individuals with IAIB express both A and B antigens on their red blood cells, while IAIA or IBIB individuals express only A or only B antigens, and ii individuals lack both. Another example is the MN blood group, where M and N alleles produce distinct antigens and the MN phenotype displays both when the genotype is MN. Codominance is also observed in coat color in some animals, such as roan cattle or horses, where heterozygotes produce a mixture of red and white hairs. A medical example is hemoglobin alleles HbA and HbS, which are codominant; individuals with HbA HbS produce both normal and abnormal hemoglobin.

Codominance is distinct from incomplete dominance, where the heterozygote phenotype is intermediate between the two homozygotes, and from complete dominance, where one allele completely masks the other. In codominant systems, the expression of both alleles can be detected and can influence phenotype in specific tissues or at specific molecular levels. Understanding codominance helps explain how certain traits and blood types are inherited and expressed in humans and other organisms.