Blue-yellow weakness is also known as third color blindness. Patients with blue-yellow confusion are less likely to be able to recognize red and green. People with blue-yellowcolorblindness have difficulty recognizing blue and yellow. Blue-yellow colorblindness includes tritanopia (third color blindness) and tritanomaly (third color weakness). Blue-yellow blindness is a form of color blindness. It is not easily detected because the patient has not been able to discriminate colors normally since childhood. It is generally believed that red-green colorblindness is determined by two pairs of genes on the X chromosome, the red-blind gene and the green-blind gene. Because these two pairs of genes are closely linked on the X chromosome, a gene symbol is commonly used to represent them. The mode of inheritance of red-green color blindness is X-linked recessive. Males have only one X chromosome and therefore only need one color blindness gene to exhibit color blindness. Females have two X chromosomes and therefore need a pair of disease-causing alleles to exhibit the abnormality. A normal female who is married to a colorblind male can pass the father’s colorblind gene to their daughter with the X chromosome, not to the son. The daughter then passes the color blind gene from her father to her son, a phenomenon known as cross-genetic inheritance. As a result, there are far more men than women with the condition.