CYP2C19 and alternating hemiplegia of childhood: Likewise, the activities of six liver CYP450s from AHC patient were reduced by about 50% for CYP1A2, 87% for CYP2C9, 80% for CYP2C19, 66% for CYP2D6, 68% for CYP2E1, and 76% for CYP3A4/5.