Question

In autosomal dominant inheritance only one "affected" what is necessary to result in an "affected" phenotype?

Answer 1

allele

Autosomal Dominant Inheritance. Only one affected allele is necessary to result in the affected phenotype. For a genetic disease inherited in this manner, only one mutant allele is necessary to result in the phenotype. Achondroplasia  discussed later  is an example of a dominant disorder. Both homozygous and heterozygous individuals will show the phenotype. Homozygous achondroplasia is usually a lethal condition.