For example, an unknown modifier associated with specific mouse genetic backgrounds can alter the penetrance of an allele (called disorganization), which causes birth defects.

Figure 2: The history of the gray treefrog, Hyla versicolor, is an example of mutation and its potential effects.When an ancestral Hyla chrysocelis gray treefrog failed to sort its 24 chromosomes ...

This makes the small allele the ancestral allele — a trait that stems from the common ancestor of canids. However, “what it was doing before 53,000 years ago, we have no idea,” Ostrander said.

For example, being heterozygous for hair color could mean you have one allele for red hair and one allele for brown hair. The relationship between the two alleles affects which traits are expressed.

Unbalanced Allele Expression Associated with Mutation, Disease. A study identifies nearly 3,000 genes where one allele tends to be expressed more than the other, but the findings ignited controversy ...

Cells had inactivated either the maternal or paternal allele of a gene in one of every twenty genes that the cell was expressing. There could be more plasticity in DNA that we appreciated, since every ...