Genetics problem... if a male hemophiliac...

Question

If a male hemophiliac (XhY) is crossed with a female carrier of both color blindness and hemophilia (XcXh), then what is the probability that a female child will be phenotypically normal?

Anyone want to explain why it's 0.500? What do they mean by phenotypically normal? Thanks a lot

Answer 1

Female offspring will be either  XcXh or XhXh. XcXh will be a carrier and will appear (phenotype) as a normal female. XhXh, however will be a hemophiliac and so has an abnormal appearance (phenotype). The ratio is 50:50 -giving a 0.5 (1 in 2) chance of a phenotypically normal female.

Answer 2

colorblindness is x linked so a female would have a much lower chance of beinf colorblind, but would probably be a carrier. I dont know much about hemophelia but if  a male hemophiliac and a female carrier  mate then the child will most likely have the trait.. and pheonytipically normal would mean normal in appearance, phenotype is how the trait presents itself and genotype is the actual DNA.

Answer 3

Phenotypically normal means not having either of the disorders (color blindness or hemophilia).

So, the Punnett square would look like this:

...........Xh..........Y.............

Xc......XcXh......XcY...........

Xh......XhXh......XhY...........

So, you would expect 1/4 of the offspring to be normal females (XcXh would be normal because there is only one mutant copy of each allele), 1/4 of to be females with hemophilia, 1/4 to be color-blind males, and 1/4 to be hemophiliac males.  Only 1/4 of all children would be phenotypically normal, but 1/2 of the female children would be.

In response to new details:

Phenotype isn't necessarily visible.  It's the result of the genotype.  So, if I have sickle-cell anemia, that's a phenotype, but you wouldn't necessarily be able to tell by looking at me.  So, having hemophilia, XhXh or XhY, is phenotypically abnormal.

Answer 4

The probability is that the poor kid will be afflicted with both blindness and hemophilia.