With respect to autosomal recessive inheritance, which, if any, of the following statements is incorrect?
A) Affected individuals normally have unaffected parents.
B) For unaffected parents who have a previously affected child, there is a 1 in 4 risk of having an affected child on each occasion that they produce a new child.
C) Heterozygotes are always asymptomatic carriers.
D) Some affected individuals have alleles with identical pathogenic mutations but many have two different mutant alleles and are described as compound heterozygotes.

Question

Quizplus · Accepted Answer

Heterozygotes can sometimes display symptoms if the disease-causing allele is dominant or if there is a phenomenon known as incomplete penetrance, where not all individuals with the disease-causing allele exhibit symptoms.

With Respect to Autosomal Recessive Inheritance, Which, If Any, of the Following