With which type of inheritance pattern does the trait or disorder usually first appear among siblings rather than in parents of affected children?
A)Autosomal dominant
B)Autosomal recessive
C)X-linked dominant
D)Codominant

Question

Quizplus · Accepted Answer

Autosomal-recessive traits and disorders must be homozygous to be expressed. Two carrier parents may be phenotypically normal although they have a heterozygous genotype because the recessive allele is not expressed in either of them. However, each can transmit the recessive allele. Any child who inherits both recessive alleles would then express the trait or disorder. The chances for expression of the trait/disorder from parents who are heterozygous is 25% with each pregnancy.

With Which Type of Inheritance Pattern Does the Trait or Disorder