Abacavir sulfate is a nucleoside reverse transcriptase inhibitor that is prescribed in combination with other antiviral drugs to treat HIV infection. In some patients, its use can cause abacavir sulfate hypersensitivity reaction (ABC HSR), a serious and sometimes fatal condition that appears within the first six weeks of treatment and is characterized by symptoms that appear suddenly and worsen with subsequent doses of abacavir. These symptoms include fatigue, rash, fever, nausea, vomiting, diarrhea, and respiratory symptoms, with fatal reactions often being associated with at least two of the above. Symptoms also generally improve within 48 to 72 hours of discontinuing abacavir treatment.Graves’ Disease is an autoimmune disease of the thyroid gland. It is characterized by hyperthyroidism associated with goiter, heart palpitations, bulging eyes, sweating, heat intolerance, tremor, anxiety and weight loss. The immunological response in Graves’ Disease comprises diffuse lymphocyte infiltration into the thyroid gland with thyroid stimulating immunoglobulin (TSI) autoantibody production. The hyperthyroidism is caused by activation of the thyroid stimulating hormone receptor (TSHR) by binding of autoantibodies.

Clinical Utility

Abacavir sulfate hypersensitivity is strongly associated with the presence of the HLA-B*57:01 allele, which can be found in most populations.  Only approximately two percent of individuals who possess the HLA-B*57:01 allele are tolerant of abacavir.  The FDA recommends that patients who are being considered for abacavir therapy be screened for the HLA-B*57:01 allele, and that patients who possess this allele not be treated using abacavir.