Colour blindness in Human beings:
The red and green colour blindness is another sex linked recessive trait in man. Individuals suffering from this defect will not be able to distinguish between various shades of red and green and hence are colour; blind.
Individually red colour blindness is called Protanopia and green colour blindness is ] called Deuteranopia. Ishihara has designed a colour chart to identify these defects It has been shown that the gene for colour blindness is a recessive allele of normal vision and is situated on the X chromosome. Like any sex linked defect, colour blindness also is more prevalent among males than among females. The Y chromosome does not carry any allele for vision.
A survey for colour blindness has not been conducted in our country, but the data available from USA give a figure of 8% for male and 0.5% for female in the total population. The following chart gives all the possible mating types and the possible progeny for colour blindness among human beings.