二次脳卒中予防における遺伝学の重要性：アジアにおけるCYP2C19の課題

Stroke is a leading cause of death and disability globally, with Asia disproportionately affected. A critical barrier to effective secondary prevention is the high prevalence of CYP2C19 loss-of-function alleles, present in almost 75% of South and East Asians, which reduce clopidogrel efficacy. Evidence from trials, including CHANCE-2 (Clopidogrel in High-Risk Patients With Acute Nondisabling Cerebrovascular Events), shows that genotype-guided alternatives, including ticagrelor and cilostazol, substantially lower recurrent stroke risk in loss-of-function carriers. Yet, clinical adoption remains limited by insufficient genetic testing infrastructure, cost, guideline gaps, and clinician training. Despite these challenges, genotype-guided therapy is both feasible and cost-effective, with the potential to reduce recurrent strokes, disability, and healthcare burden. Urgent action is required to implement precision antiplatelet strategies, update guidelines, and ensure equitable access, making pharmacogenomics a central component of stroke care in Asia.