HLA gene for abacavir hypersensitivity is?

Drug allergies are the most significant allergic reactions occurring in HIV-infected patients and appear to become more common as the disease progresses. Anaphylaxis is extremely rare in patients with HIV infection, and patients who have a cutaneous reaction during a single course of therapy can still be considered candidates for future treatment or prophylaxis with the same agent. The one exception to this is the nucleoside analog abacavir, where fatal hypersensitivity reactions have been repoed with rechallenge. This hypersensitivity is strongly associated with the HLA-B5701 haplotype, and a hypersensitivity reaction to abacavir is an absolute contraindication to future therapy. Ref: Harrison&;s Principles of Internal Medicine; 19th edition; Chapter 226; Human Immunodeficiency Virus Disease: AIDS and Related Disorders; Page no: 1260