Polymorphism at codons 114, 116, 145, and 163 muddle the typing of HLA-B*1304.

Genetic exchanges often muddle the typing of HLA class I molecules, this is also the case for HLA-B1304. Serologic and molecular DNA class I typing report a B15/B55 type for cell 847, whereas DNA sequencing finds B5501/B1304. HLA-B1304 differs by no more than four amino acids from other HLA-B13 molecules, a comparative analysis of the B13 and B15 families was therefore performed to determine why serologic and molecular DNA approaches report a B15 type for B1304. Comparisons demonstrate that limited differences individuate the B15 and B13 molecules such that the genetic recombination of codons 145 and 163 in the class I heavy chain's alpha 2 alpha helix prompt B1304 to exhibit a B15X21 pattern of serologic cross-reactivity. Molecular DNA class I typing approaches are also swayed by genetic recombinations to type B1304 as a B15 molecule: B15-like nucleotide sequences encoding residues 114, 116, and 145, lead B1304 to exhibit a B15 PCR amplification pattern. Thus, genetic exchanges encoding key amino acids in the class I heavy chain lead molecular and serologic typing approaches to categorize HLA-B*1304 as a member of the B15 family.