In autosomal recessive inheritance, can an affected individual have unaffected parents?

• A. They have two mutated copies.
• B. Carriers show the disease phenotype.
• C. An affected individual can have unaffected parents.
• D. Two affected parents always produce affected child.

Answer: (C)

In autosomal recessive inheritance, you must inherit two mutated copies to show the disease. That means an affected person has one mutated allele from each parent. If the parents are unaffected, they can still both be carriers (each has one mutated and one normal allele). When two carriers have a child, there’s a real chance the child will inherit the mutated allele from both sides and be affected, while other children can be carriers or completely normal. So yes, an affected individual can have unaffected parents. Carriers don’t usually show the disease, which is why the parents appear unaffected. If both parents were affected, they would almost always have affected children as well, which isn’t the scenario described.