A definition of dominant mutation

studious

This is a question of semantics(?). Biologists are not known to be gods of well-definedness, but if there actually exists an argument over the following question (even a possibility), then I might get some credit back on some classwork.

What is the definition of a dominant mutation (of a nucleotide of an allele at some locus)?

1. That the mutation yields a new allele which is necessarily dominant w.r.t. to the un-mutated (old) allele.

2. That the mutation yields a new allele which is necessarily dominant to "other" alleles (or perhaps co-dominant with the unmutated version).


Co-dominance of two alleles at a locus implies that they are both equally dominant over other alleles.

Andy Resnick

My understanding of "autosomal dominant" is that the phenotype is displayed under heterogeneous expression. In addition, "dominant negative" mutations mean that the mutated gene product affects the function of the normal gene product (a 'gain of function' mutation).

Does that help?

studious

Not good enough.

Is "dominance" ordered for a set of alleles? Are there different levels of dominance? The term dominance itself is too vague.

(sure gain of function mutations are "usually" dominant; however, silent mutations of dominant alleles also retain dominance... in fact co-dominance with the non-mutated versions... over time - generations - they may come into equal allele frequencies... whatever the actual values.)