Certified Neuroscience Registered Nurse (CNRN) Practice Exam

The inheritance of adrenoleukodystrophy (ALD) is primarily related to which type of gene?

1. Autosomal dominant gene

2. X-linked recessive gene

3. Autosomal recessive gene

4. Y-linked gene

The correct answer is: X-linked recessive gene

Adrenoleukodystrophy (ALD) is primarily associated with an X-linked recessive gene, which means the gene responsible for the disorder is located on the X chromosome. This genetic characteristic is crucial for understanding the inheritance pattern of ALD, as it significantly influences how the condition is passed from parents to offspring. In X-linked recessive inheritance, males are typically affected if they inherit one copy of the mutated gene from their mother, who may be a carrier. Females, on the other hand, usually need two copies of the mutated gene to express the disorder, which is rarer since females have two X chromosomes. Consequently, this pattern leads to a higher prevalence of ALD in males. Recognizing this inheritance pattern is vital in genetic counseling, diagnosis, and understanding the familial implications of ALD. The fact that ALD is linked to a gene on the X chromosome differentiates it from other inheritance types, such as autosomal dominant, autosomal recessive, or Y-linked traits, which follow different mechanisms of transmission.