CYP2C19 gene variant analysis

Clopidogrel is an antiplatelet drug commonly prescribed after ischaemic stroke or transient ischaemic attack to help reduce the risk of blood clots that could lead to further strokes. Clinical evidence indicates that individuals with loss-of-function CYP2C19 alleles are more likely to have further strokes compared with people without loss-of-function alleles as clopidogrel is not as effective. These patients may be offered alternative antiplatelet therapies (CYP2C19 genotype testing to guide clopidogrel use after ischaemic stroke or transient ischaemic attack, NICE, diagnostic guidance [DG59], 31 July 2024). Mavacamten is indicated for the treatment of obstructive hypertrophic cardiomyopathy. The European Medicines Agency (EMA) label for mavacamten suggests that patients should be genotyped for CYP2C19 to determine the appropriate drug dose to avoid increased risk of systolic dysfunction side effects (EMA, summary of product characteristics).