Question

Study the pedigree chart given below.

It shows that:

• A. Inheritance of a recessive sex-linked disease like haemophilia.
• B. Inheritance of a sex-linked disease like colour blindness.
• C. Inheritance of a condition like phenylketonuria as on autosomal recessive trail.
• D. The pedigree chart is wrong as this is not possible

Answer 1

The correct option is C

Inheritance of a condition like phenylketonuria as on autosomal recessive trail.

Phenylketonuria is an inherited autosomal recessive disease that causes an increase in the blood of a chemical known as phenylalanine. In the parental generation, none of the parents is affected. So the disorder is not a dominant disorder.

In the first generation, both the sexes are equally affected and mother and father, in both the generations, are not affected. So it is not an X-linked disorder. This pedigree chart thus shows autosomal recessive disease like phenylketonuria.