The first-generation HSP90 inhibitor, 17-AAG, can cause severe hepatotoxicity.32 Neurological toxicities such as syncope and dizziness have been observed upon using the second-generation HSP90 inhibitor BIIB021.33 In clinical trials of other HSP90 inhibitors, the most commonly observed adverse events have been reversible visual disorders, which interfere with obtaining sufficient drug exposure, because of drug interruption or discontinuation or dose reduction.32–36. The gene discussed is HSP90AA1; the disease is vision disorder.