Duchenne muscular dystrophy is inheritance of:
**Core Concept**
Duchenne muscular dystrophy (DMD) is a genetic disorder characterized by progressive muscle degeneration and weakness. It is caused by mutations in the dystrophin gene, which codes for a protein essential for muscle function.
**Why the Correct Answer is Right**
The correct answer is X-linked recessive inheritance. This is because the dystrophin gene is located on the X chromosome, and mutations in this gene lead to DMD. Since males have only one X chromosome, a single mutation in the dystrophin gene is sufficient to cause the disease, while females, who have two X chromosomes, are typically carriers unless they inherit two mutated copies.
**Why Each Wrong Option is Incorrect**
**Option A:** Autosomal dominant inheritance is incorrect because DMD is not caused by a mutation in a single gene on an autosome (non-sex chromosome). Also, autosomal dominant disorders typically affect both males and females equally.
**Option B:** Autosomal recessive inheritance is incorrect because DMD is not caused by mutations in two alleles of a gene on an autosome. While females can be carriers, they typically do not express the disease.
**Option C:** Mitochondrial inheritance is incorrect because DMD is not caused by mutations in the mitochondrial DNA.
**Clinical Pearl / High-Yield Fact**
DMD is one of the most common genetic causes of childhood muscular dystrophy, and it typically presents in early childhood with symptoms such as muscle weakness, wasting, and difficulty walking.
**Correct Answer: C. Mitochondrial inheritance is incorrect because DMD is not caused by mutations in the mitochondrial DNA.