A common autosomal recessive allele can produce a pedigree that looks like an autosomal dominant tra

A common autosomal recessive allele can produce a pedigree that looks like an autosomal dominant trait. In generation I, one parent is homozygous for the type O recessive allele (ii) and the other is heterozygous. In generation II, two new copies of the i allele are introduced into the family (II-1 and II-7), producing three ii homozygotes in generation III. As a result, inheritance of this common autosomal recessive allele produces a pseudo-dominant pedigree, with members of each generation showing the trait and about one-half of the offspring in each generation exhibiting the trait.