Question

Duchenne muscular dystrophy is

• A. Autosomal disorder
• B. Dominant autosomal disorder
• C. Sex linked disorder
• D. Recessive autosomal disorder

Answer 1

The correct option is C Sex linked disorder

Duchenne muscular dystrophy is a X-linked recessive disorder. The associated genes are located on the X chromosome, which is one of the two sex chromosomes. Since males are hemizygous for chromosome (have only one X chromosome), one copy of the affected gene in each cell is sufficient to cause the disorder. Females have two X chromosomes and hence need two copies of the affected gene to cause the disorder. Females heterozygous for this trait be normal but serve as a carrier of the disease. Since frequency of females with two altered copies of this gene, males are affected by this disorders much more frequently than females. Duchenne muscular dystrophy is never passed from father to sons because fathers cannot pass X-linked traits to their sons. Thus, Duchenne muscular dystrophy is a sex linked disease not an autosomal trait which is passed to both sex with equal frequency. Option C is correct answer.