When comparing HLA alleles between a parent and a child, how many are typically expected to match?

When assessing the expected matches of HLA alleles between a parent and a child, it is important to understand the inheritance pattern of HLA genes. Each person inherits one set of HLA alleles from each parent, making a total of two sets from both parents.

HLA (Human Leukocyte Antigen) molecules are critical for the immune system's ability to distinguish between self and non-self. They are highly polymorphic, meaning there are many different alleles present in the population.

Typically, a child inherits one HLA allele from each parent for each of the three main HLA loci: HLA-A, HLA-B, and HLA-DR. This results in a potential match of six alleles in total (three from each parent), but given that each child will inherit a single allele from each parent at each locus, they can match up to three of the six alleles - one from each locus on average.

Therefore, when comparing HLA alleles, it is expected that typically 3 alleles will match between the parent and child, corresponding to one allele from the HLA-A, one from HLA-B, and one from HLA-DR locus. This matches the general understanding that a child will have