NEETZoologyPrinciples of Inheritance and Variation
Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): In a family pedigree, a person suffering from myotonic dystrophy must have at least one affected parent. Reason (R): Myotonic dystrophy is an autosomal Mendelian disorder. In the light of the above statements, choose the correct answer from the options given below:
Options
- ABoth (A) and (R) are true and (R) is the correct explanation of (A)
- BBoth (A) and (R) are true but (R) is not the correct explanation of (A)
- C(A) is true but (R) is false
- D(A) is false but (R) is true
Correct answer
B. Both (A) and (R) are true but (R) is not the correct explanation of (A)
Step-by-step solution
Assertion (A) is true: Myotonic dystrophy is an autosomal dominant trait. Since it is a dominant disorder, the defective allele expresses itself even in a heterozygous condition. Therefore, the trait does not skip generations, and an affected individual must have inherited the allele from at least one affected parent. Reason (R) is true: Myotonic dystrophy is indeed an autosomal Mendelian disorder. However, Reason (R) is not the correct explanation for Assertion (A). The correct explanation for the trait not skippi