## **Core Concept**
Kinky hair disease, also known as Menkes disease, is a disorder that affects copper levels in the body, leading to symptoms such as peculiar hair, brain degeneration, and early death. This condition is inherited in an X-linked recessive pattern.

## **Why the Correct Answer is Right**
The correct answer, X-linked recessive inheritance, fits the family history provided. In X-linked recessive inheritance, males are more frequently affected than females because they have only one X chromosome. Females can be carriers, and they have a 50% chance of passing the mutated gene to each son, who would be affected, and to each daughter, who would typically be a carrier like her mother. The fact that Mrs. A's two sisters had affected sons and her maternal uncle also had the condition suggests that her mother is likely a carrier, and the condition is being passed down through the maternal lineage.

## **Why Each Wrong Option is Incorrect**
- **Option A (Autosomal Dominant):** This pattern would mean a single copy of the dominant allele is enough to cause the condition. Affected individuals would have a 50% chance of passing the condition to each child, regardless of gender. This does not fit with the family history provided, where the condition seems to affect males and be carried by females.
- **Option B (Autosomal Recessive):** For a condition to be autosomal recessive, an individual must inherit two copies of the mutated gene (one from each parent) to be affected. This would not explain the maternal lineage of affected males and carrier females as described.
- **Option D (Y-linked):** Y-linked inheritance would mean the condition is passed from father to son. Since the condition affects females (as carriers) and is described in a maternal lineage, this is not a plausible explanation.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that X-linked recessive conditions, like Menkes disease, often present with severe symptoms in males (who have one X chromosome) and are carried by females (who have two X chromosomes). A classic example of another X-linked recessive disorder is hemophilia A. When evaluating family histories for genetic conditions, looking for a pattern of maternal inheritance of a condition that predominantly affects males can suggest X-linked recessive inheritance.

## **Correct Answer:** . X-linked Recessive.