Protanopes often can name red and green correctly because green looks lighter to them than red. Males have red-green defects if they inherit a defective gene from their mother. Affected males pass the defective gene to all of their daughters but none of their sons. Females who inherit only one defective gene are carriers of that gene. Females who inherit the gene for red-green defect from both parents are affected.
Hereditary tritanopia is a blue-yellow defect.
Persons with blue-yellow defects cannot see the difference between blues and yellows but can distinguish between reds and greens. Triatnopes usually have fewer problems in performing everyday tasks than do those with red-green dichromacy. The ability of anomalous trichromats to distinguish between hues is better than dichromats but still not normal. Red-green anomalous trichromacy is subdivided into protanomaly and deuteranomaly . Both types are inherited in the same way as for red-green dichromacy.