Polydactyly (extra fingers or toes) in humans is inherited as an autosomal dominant trait. Some heterozygotes, however, do not have any visible abnormality. This situation could result from
A) a reduced level of penetrance.
B) reduced expressivity.
C) incomplete dominance.
D) polygenic inheritance.
E) phenotypic variability

Question

Quizplus · Accepted Answer

A reduced level of penetrance explains the situation where some individuals with the dominant allele for polydactyly do not express the trait, meaning not all individuals with the allele show the phenotype.

Polydactyly (Extra Fingers or Toes) in Humans Is Inherited as an Autosomal