What is the probability of the two parents having a son with muscular dystrophy?

Biology
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A woman with muscular dystrophy marries an unaffiliated male

a) What are the genotypes of both parents?

mom=                      dad=

What is the probability of the two parents having a son with muscular dystrophy?

May 5th, 2015

mum=Xx(small x indicates carrier )         dad=XY

the gene for DMD is located on the X chromosome. Since the defective gene is recessive, a female with the DMD gene on one of her two X chromosomes will not develop muscular dystrophy. The normal gene on her second X chromosome masks the effects of the defective gene. Such a woman is called a "carrier". Male offspring, however, have only one X chromosome, and there are no equivalent genes on the Y chromosome. Consequently, in males the X-chromosome genes have no "partners". Therefore, a male with the DMD gene on his X chromsome will be affected with the condition because he has no normal gene to counteract the effect of the abnormal one

WHEN THE MOTHER IS HAVING THE DISEASE, OUT OF FOUR OFFSPRINGS, TWO WILL BE CARRIERS AND TWO OTHER WILL BE HAVING THE DISEASE


May 5th, 2015

So their will be a 50% chance that her son will have DMD?

May 5th, 2015

true......because the son will get one X chromosome from the mother and either X or Y from father. the son who get the Y is the sick one . hence 50% chance

May 5th, 2015

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May 5th, 2015
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