GNAT2 and achromatopsia: Subjects present at birth or early infancy with nystagmus, reduced visual acuity, photoaversion, and reduced or absent color vision.1,2 Disease-causing sequence variants in the genes encoding the alpha and beta subunits of the cone-specific cyclic nucleotide gated ion channel (CNGA3 and CNGB3, respectively) account for approximately 70% of all cases of ACHM,3 although variants in genes encoding for other components of the cone phototransduction pathway (GNAT2, PDE6H, PDE6C)4, –6 have also been associated with ACHM.