PRDM9 and early-onset non-syndromic cataract: Many of the genes are involved in transcriptional regulation: PRDM9 encodes a histone H3 lysine-4 trimethyltransferase [23]; CTDP1 functions in recruiting RNA polymerase to DNA promoters and is an OMIM gene for congenital cataracts, facial dysmorphism and neuropathy [24]; TFB2M regulates mtDNA transcription and maintenance [25]; also ZNF300, ZNF274 and ATF7IP2 are transcriptional regulators [26–28].