In the context of HLA testing results, A2, B12, C22, DR5 is best referred to as?

The designation A2, B12, C22, DR5 refers to a specific combination of HLA (Human Leukocyte Antigen) types at different loci, which together constitute a haplotype. A haplotype is defined as a set of alleles at multiple loci that are transmitted together. When assessing HLA types, this combination reflects the inherited alleles from one parent, typically focused on maternal or paternal origins.

In this case, the answer indicates a maternal haplotype, suggesting it’s highlighting the complete set of alleles on one chromosome inherited from the mother. Recognizing it as a haplotype is crucial because it emphasizes that these alleles are linked and often inherited as a block, which has significant implications in transplantation and disease susceptibility.

The other terms like phenotype, locus, and allele refer to broader concepts or specific components within the HLA system, but do not accurately characterize the grouping provided in the question. A phenotype indicates the overall expression of an individual's genetic traits, while an allele denotes a specific form of a gene at a particular locus. Referring to an allele or locus does not capture the essence of the entire set manifested in the answer.