Question

Choose the most appropriate statement for the given pedigree analysis.

• A. Inheritance of a trait in a sex linked dominant manner
• B. The pedigree chart is wrong as this is not possible
• C. Inheritance of a trait in a sex linked recessive manner
• D. Inheritance of a trait in an autosomal recessive manner

Answer 1

The correct option is D Inheritance of a trait in an autosomal recessive manner

A pedigree chart depicts the transmission of a particular trait that runs in a family. It can be either autosomal or sex linked and recessive or dominant.
In the given pedigree chart, the parents are unaffected, but some of their progeny are affected. This indicates that either of the parents are carriers of the genetic disease. Hence the trait is recessive. If it were dominant, one or both the parents would have been affected.
In the second generation, males and females are almost equally affected. So, this is an autosomal disease.
It is not a sex linked disease, because in case of males, sex linked disorders (whether X- linked or Y- linked) are always expressed, irrespective of wheter they are dominant or recessive.
Hence, the pedigree shows the inheritance pattern of an autosomal recessive trait.