Colour blindness


Looking at sex-linked inheritance as traits whose genes are located on sex-chromosome or X chromosome. View from human beings angle, sex is determined by a pair of chromosomes refers to as sex chromosomes, having that XY mechanism. The male is heterogametic XY and the woman is homogametic that’s XX. Though, the genes present on sex chromosome in women are in double doze just the same way as genes present on autosomes. But in man, the genes present on the X chromosome are in a single dose as the Y chromosome does not carry homologous genes to those on the X chromosome.

The sex-linked genes exhibit a crisp-cross pattern of inheritance, eg, the genes present in x chromosomes of the male can never be transferred to male progenies of the first generation, but to females only. The genes picked from the male parent by the female are passed on to half percent of the male progeny of the next generation.

This is-cross pattern of inheritance is tag sex-linked inheritance. examples of sex-linked inheritance in every human being are Hemophilia and color blindness.

Therefore color blindness can be defined as a genetic disease that is sex-linked but can also come from acquired deficiencies. There are several, different, varieties of color-blindness, red-green color blindness, blue-yellow color blindness, blue-cone monochromacy, and other ones that are not as common. Color vision is prevented by cones and rods, and defects may cause these cones or rods to not work. Mutations in OPN1LW, OPN1MW, and OPN1SW cause color blindness. Because every color vision deficiency varies, there are different genetic causes and probabilities of inheriting the disease. Rarely, however, are individuals unable to see any color at all.

Red-green color-blindness is one of the color blindness which is the most common of the color vision deficiencies. It is also related to sex-linked genetic disease because this is common among males. The X from the sex chromosome carries the recessive gene, and only x recessive needed to get the disease. Most time, males get the disease from mothers, recessive X, and dominant X together, and get the Y from the father. For males, the probability of getting red-green color-blindness is about 1/12 but for females, it is 1/200. Individuals with this disease have trouble distinguishing between shades of red, green, and yellow. Those, there is another type of color blindness which is green color blindness.



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