KCNQ5 and congenital rubella syndrome: Although our study and previous work suggests the plausible role of apical potassium channel genes in CRS pathogenesis, only a small proportion of variance in CRS occurrence is explained by the independent significant SNPs in KCNMA1 or KCNQ5. This is not surprising as CRS is a common, complex disease phenotype determined by multiple factors, including both genetic and environmental factors.