HLA-B and acute respiratory distress syndrome: Trimethoprim-sulfamethoxazole (TMP-SMX)-induced acute respiratory distress syndrome (ARDS) is a rare but potentially fatal adverse drug reaction, most reported in young, otherwise healthy individuals.[1,2] Recent literature from the United States has identified a strong association with HLA-B*07:02 and C*07:02 alleles.[1,3,4] TMP-SMX is a widely prescribed antibiotic, commonly used for prophylaxis and treatment of Pneumocystis jirovecii pneumonia, urinary tract infections, and other bacterial infections.