Stevens–Johnson syndrome
HLA-B*5801 is involved in allopurinol sensitive drug induced Stevens–Johnson syndrome. Allopurinol is a frequent cause of severe cutaneous adverse reactions, including drug-hypersensitivity syndrome, Stevens–Johnson syndrome, and toxic epidermal necrolysis (SJS/TEN). The association with allopurinol sensitivity in SJS/TEN was extremely strong in Asia, and somewhat less associated in Europeans.