In modern humans, the CYP2C9*2 haplotype has decreased enzyme activity compared to the reference haplotype (Van Booven et al. 2010), and negatively affects warfarin metabolism (Rettie et al. 1994), increases the risk of hypoglycemia from sulfonylurea treatments (Chen et al. 2020), and increases the risk of overdose on phenytoin (Ninomiya et al. 2000). The gene discussed is CYP2C9; the disease is Hypoglycemia.