What this means

HLA-B*57:01 is one of the clearest examples of pharmacogenetics in clinical practice. Abacavir hypersensitivity in carriers can be severe or fatal; in non-carriers it is rare. Pre-treatment screening reduces hypersensitivity from roughly 8% to near zero. rs2395029 is a tag SNP that correlates strongly (but not perfectly) with the HLA-B*57:01 allele; clinical confirmation is recommended before any decision.

HLA-B*57:01 is a particular version of an immune system gene, and it's one of the most clear-cut examples of how genetics can guide prescribing. People carrying it are at substantially higher risk of a severe — sometimes fatal — allergic reaction to abacavir, a drug used to treat HIV. In people without HLA-B*57:01, this reaction is rare. By checking for this version before starting abacavir, the rate of severe allergic reactions drops from about 8% to nearly zero. The DNA reading here is a strong marker for HLA-B*57:01 but isn't perfect, so a doctor would usually do a confirmatory HLA test before making any final decision.

Caveats

• Tag SNP correlation with the actual HLA allele is high but not perfect; confirm with clinical HLA typing.
• This finding only matters if abacavir or any abacavir-containing regimen is considered.
• HLA-B*57:01 has been linked to other drug hypersensitivities, but abacavir is by far the most validated.

References

• Mallal et al. — HLA-B*5701 screening for hypersensitivity to abacavir (NEJM, 2008)
• Martin et al. — CPIC Guidelines for HLA-B Genotype and Abacavir Dosing (2014)