The similar clinical presentation between familial achromatopsia in humans and bovine recessive day-blindness led to the hypothesis that a protein-changing variant within CNGA3, CNGB3, GNAT2, ATF6, PDE6C, and PDE6H would be associated with achromatopsia of Original Braunvieh calves. The gene discussed is GNAT2; the disease is blindness (disorder).