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A phenotype that occurs even when the causal allele occurs in a heterozygous individual.

Use in clinical context

Individuals have two copies of each gene, with the exception of genes on the sex chromosomes in males, and both copies can contribute to an individual’s phenotype. When a dominant allele is present, the phenotype seen is associated with that allele. However, dominant alleles can still be influenced by other factors, which can result in the phenotype not being expressed or different forms of presentation, despite the presence of the dominant allele.

Last updated on 22nd October, 2020