CNGA3 and achromatopsia: To date, ACHM has been described as being caused by mutations in four genes: cyclic nucleotide-gated channel alpha-3 (CNGA3), cyclic nucleotide-gated channel beta-3 (CNGB3), guanine nucleotide-binding protein, alpha-transducing activity polypeptide 2 (GNAT2), and phosphodiesterase 6C (PDE6C) [9-14].