Question

Inheritance of total color blindness is?
(a) X-linked
(b) XY-linked
(c) Y-linked
(d) None of the above

Answer 1

Genetic disorders which are caused by the affected father to his grandsons through his carrier daughter. They are restricted to the males who carry mutant genes.

Complete answer:
In colorblindness, mutation takes place on the X chromosome which causes the phenotype to be expressed in hemizygous males for the recessive allele. It is an X linked recessive inheritance restricted only to males who carry the mutant allele.

Additional Information: Genetic disorders caused due to mutation on X chromosome genes are X-linked disorders.
- X linked disorders are mostly recessive and are restricted to a male who carries the mutant allele.
- Color blindness is a sex-linked recessive disorder in which the retina of the eye is unable to differentiate red and green color
- When a homozygous woman marries a man with color blindness. Both male and female offspring are normal but the daughters are carriers of color blindness.
- when a heterozygous woman gets married to a man without color blindness, all the daughters and half of the sons are normal and the remaining half of the sons are born with color blindness.
- Color blindness is also an example of a criss-cross pattern of inheritance because it is inherited to the grandson by the male parent through the carrier daughter
- The most common examples of X-linked recessive disorders are color blindness, Duchenne muscular dystrophy, Hemophilia, etc.
So, the correct answer is ‘X-linked’

Note: Colour blindness is of two types namely protanopia and deuteranopia
In X-linked recessive disorders, all the color blind daughters have a color-blind father and carrier or affected mother.
50 percent of grandsons are affected by the affected father through their carrier daughter.