An X-linked homozygous color-blind woman gives birth to a son who is not color blind. He could have normal vision because he?

A) has Turner syndrome.
B) is XYY.
C) has Down syndrome.
D) has triploidy.
E) has Klinefelter syndrome.

Question

An X-linked homozygous color-blind woman gives birth to a son who is not color blind. He could have normal vision because he? 

A) has Turner syndrome.  
B) is XYY.  
C) has Down syndrome.  
D) has triploidy.  
E) has Klinefelter syndrome.

anonymous · Answer

I think the answer is E Kleinefelter's syndrome. Normally a homozygous color-blind woman would not have any unaffeted male children because the inherited x chromosome would have the mutation. In Kleinefelter's, two X chromosomes and a Y chromosome are found in the male child, so possibly one of the X chromosomes comes from the non color-blind father (from non disjunction of chromosomes at meiosis I)