Question

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 beast cancer in his family. What are the probable genotypic and phenotypic ratios of their male children?

Answer 1

Answer:

Muscular Dystrophy : 50%

Breast cancer: 50%

Explanation:

Muscular Dystrophy (linked to X):

1/2 (mother) x 2/2 (father) = 2/4 (50%) chance of having an affected child with MD

Breast cancer (autosomal dominant disorder):

1/2 (mother) + 0 (father) = 1/2 = 50% chance of having an affected child with breast cancer