**Core Concept**
MELAS syndrome is a rare mitochondrial disorder characterized by mitochondrial DNA mutations, leading to impaired energy production in cells. The inheritance pattern of MELAS syndrome is primarily matrilineal, as it is inherited from the mother.

**Why the Correct Answer is Right**
MELAS syndrome is caused by mutations in the mitochondrial DNA, which is inherited solely from the mother. Mitochondrial DNA is not mixed with the father's DNA during fertilization, making it a matrilineal trait. This is due to the fact that only egg cells contribute mitochondria to the fertilized egg, while sperm cells do not. As a result, children can only inherit mitochondrial DNA mutations from their mothers.

**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect because MELAS syndrome is not inherited in an autosomal dominant manner, which would imply equal transmission from both parents.
**Option B:** Incorrect because MELAS syndrome is not a result of a single-gene mutation, but rather a mitochondrial DNA mutation.
**Option C:** Incorrect because MELAS syndrome is not inherited in an X-linked recessive pattern, which would primarily affect males.
**Option D:** Incorrect because MELAS syndrome is not a result of a chromosomal abnormality, such as a translocation or inversion.

**Clinical Pearl / High-Yield Fact**
MELAS syndrome is a classic example of a mitochondrial disorder, and its matrilineal inheritance pattern is a key distinguishing feature. This should be remembered when considering the differential diagnosis for patients with symptoms of mitochondrial dysfunction.

**Correct Answer: A. Autosomal dominant.