In humans Muscular Dystrophy is an Xlinked recessive disorde

In humans, Muscular Dystrophy is an X-linked recessive disorder. Inheritance of the BRCA1 gene that can cause breast cancer in women and is an autosomal dominant disorder. A woman, who has tested positive for one copy of the BRAC1 allele, does not, have muscular dystrophy. There is no history of muscular dystrophy in her family, but her mother died of breast cancer. The woman is married to a man who has muscular dystrophy. There is no history of BRAC1 breast cancer in his family. What are the probable genotypic and phenotypic ratios of their children?

Solution

X^X × X`Y

Gametes are: x^ (brca1 dominant allele) x ; x` (muscular dystrophy recessive allele) y

Possible combinations:

Inheritance of this autosomal dominant allele in the male or female offsprings is 50% there Grand daughters will also have lifetime risk of 56 to 80% of breast cancer and 10 to 60% of ovarian cancer.

Gametes/	x^	x
X`	x`x^	x`x
y	x^y	xy