How are most blood group systems inherited?

Blood group systems are inherited through autosomal codominant inheritance. This means that when an individual possesses two different alleles for a blood group gene, both alleles are expressed in the phenotype. For example, in the ABO blood group system, a person who inherits an A allele from one parent and a B allele from the other will express the AB blood type, demonstrating the co-dominance of both A and B alleles.

In terms of genetics, this contrasts with other forms of inheritance, such as sex-linked traits, which are associated with the sex chromosomes and can manifest as dominant or recessive. However, the classic blood group systems, such as ABO and Rh, are not located on sex chromosomes but rather on autosomes (non-sex chromosomes), which determines their mode of inheritance as autosomal instead of sex-linked. Thus, the unique characteristics of blood group inheritance reinforce the understanding of genetics within the context of blood banking and transfusion practices.