The below is from a 2009 publication

HLA-B27 represents a family of 38 closely related cell surface proteins (encoded by the alleles HLA-B*2701-39) called subtypes of HLA-B27, most of which evolved from the ubiquitous HLA-B*2705 (specifically the B*27052 allele). HLA-B27 subtypes are largely characterised by nucleotide substitutions (mostly nonsynonymous)in exons 2 and 3 which encode the alpha1 and alpha2 domains of the peptide binding groove respectively.

Subtypes with substitutions in the First Domain (alpha1)

HLA-B*2702, the most frequently occuring allele of this group, occuring primarily in those of Middle Eastern, Northern African and European ancestry. It is restricted to Caucasoids and accounts for 5-10% of HLA-B27 subtypes in Europeans.
HLA-B*2703 - next most common of this group - most likely evolved in West Africa ......

HLA-B*2716, first described in Causcasians, differs from B*2705 at three amino acids at positions 69, 70 and 71 - and has no known disease association to date.

Other members of this group are quite rare and probably evolved recently, characterised by a single nucleotide mutation, including HLA-B*2716, B*2737 and B*2739, which likely evolved directly from B*2705. HLA-B*2717 shows one mismatch at position 248(A->T), considered to be a conserved position in nearly all B alleles, which results in a phenyalanine for tyrosine substitution

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I don't think HLA-B27 subtyping is done commercially - probably just a research tool.

Dx Oct 2006 B27+ undifferentiated spondlyarthropathy (uSpA) with mild sebhorrhoeic dermatitis and mild Inflammatory Bowel Disease (IBD) controlled by NSD since 2007.