How many dominant alleles are needed for a dominant genetic disorder to be expressed?

1 Answer
Feb 28, 2018

One dominant allele.

Explanation:

A dominant allele overrides any recessive allele, so if an individual is heterozygous (Dd) or homozygous dominant (DD), they will only express the dominant trait (D). An individual must be homozygous recessive (dd), to express the recessive trait (d).