Question
Biology Question on Principles of Inheritance and Variation
In the following human pedigree, the filled symbols represent the affected individuals. Identify the type of given pedigree.
A
Autosomal recessive
B
X-linked dominant
C
Autosomal dominant
D
X-linked recessive
Answer
X-linked recessive
Explanation
Solution
The given pedigree is not of dominant disorder as III-6 and III-7 are not affected by the disorder. The given pedigree is of X-linked recessive disorder.
In generation I, the female is a carrier of the disease and male is affected by the disease. In generation II, the female receives the affected genes from both mother and father.
When II-1 marries a normal male, none of the offsprings are affected by the disease. However, the female of generation III is a carrier of the disease as she received the defective gene from the mother.