Which of the following disorders is classified as autosomal recessive?

• A. Hemophilia A
• B. Huntington's disease
• C. Marfan syndrome
• D. Cystic fibrosis

Answer: (D)

Verified step by step guidance

1. Understand the difference between autosomal recessive and other inheritance patterns. Autosomal recessive disorders require two copies of the mutant allele (one from each parent) for the individual to express the disorder.
2. Review the inheritance patterns of the given disorders: Hemophilia A is X-linked recessive, Huntington's disease is autosomal dominant, and Marfan syndrome is autosomal dominant.
3. Recall that cystic fibrosis is caused by mutations in the CFTR gene and follows an autosomal recessive inheritance pattern, meaning affected individuals have two defective copies of the gene.
4. Confirm that the question asks which disorder is autosomal recessive, so identify cystic fibrosis as the correct choice based on its inheritance mode.
5. Summarize that cystic fibrosis is the only disorder listed that is inherited in an autosomal recessive manner, distinguishing it from the others.