Some studies have shown that the amount of complement C3 in the peripheral blood of sick patients with congenital cataracts is dramatically decreased, and the reduction of complement C3 is a risk factor for congenital cataracts (Shi et al. 2003; Ge et al. 2014; Shao et al. 2017; Li et al. 2017). This evidence concerns the gene C3 and early-onset non-syndromic cataract.