A couple who are both carriers of the gene for cystic fibrosis have 2 children who have cystic fibrosis. What is the probability that their next child will have cystic Fibrosis?

*ans-25%*

I need help computing the genotypes of the parents.

I get the genotypes to be XRXr and XRYr????

Also another problem closely related—
An achondroplastic dwarf man with normal vision marries a color-blind woman of normal height. The man’s father was of normal height and both of the woman’s parents were of average height. Achondroplastic dwarfism is autosomal dominant and red-green color blindness is X-linked recessive. How many of their female children might be expected to be color-blind dwarfs?? and how many of their male children would be color blind and normal height??

**ans. 0-female color blind dwarfs && half male color blind normal height**

I have the genotypes as XbXb and XBYa

Any corrections or suggestions would be appreciated!!