If a colour blind female marries a man whose mother was also colour blind, what are the chances of her progeny

Question

If a colour blind female marries a man whose mother was also colour blind, what are the chances of her progeny having colour blindness?

Accepted Answer

Colour blindness is a sex-linked recessive disorder. Let the recessive allele be .
1. Female Genotype: Since she is colour blind, she must be homozygous recessive: .
2. Male Genotype: The man has a colour blind mother (). Males receive their X chromosome from their mother. Therefore, he received  from her. His genotype is  (he is also colour blind).
3. The Cross:  (Female)   (Male).
4. Progeny:
   - Daughters receive  from mother and  from father   (Colour blind).
   - Sons receive  from mother and  from father   (Colour blind).
Since all offspring are affected, the chance is 100% .

Step-by-Step Solution

Practice All BIOLOGY Questions