Please answer my question experts

Dear student,
Please find below the answer:

If a disorder is X-linked recessive like colour blindness, then there would be a smaller proportion of females suffering (as XcXc condition is required in females to suffer,  which is very rare ) while there would be a higher male percentage suffering from it as they do not have corresponding X allele. 

Males can never be carriers of colour blindness. Since males have only one X chromosome, the allelic counterpart is absent so the trait is always expressed in males and hence they cannot be carriers. Females can be carriers as well as colour blind (sufferers). As we know, females have XX chromosomes so, if a gene on one of the chromosomes is affected, it will be compensated by the other and in this condition females become carrier.

Another characteristic of X-linked disease like colour blindness is that X-linked traits cannot pass from fathers to their sons. It shows crisscross inheritance because in this disorder father passes the gene for disorder to the carrier daughter who then transmits it to the son.

So, if the father is color blind then this trait will not get pass onto the son, therefore son will be normal XY. The trait will get passed from a color blind father to his daughter and she will be a carrier in this case which can be denoted by XCX.

Now, according to your question, the male will be normal i.e. XY and female will be a carrier i.e.  XCX (since her father is colourblind). It will give XCX, XX, XCY and XY. Therefore, the chances of their daughter being colorblind is 0% while 25% of daughters will be carrier.

Hope this clears your doubt.

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