Muller's morphs

Amorph Amorphic describes a mutation that causes complete loss of gene function. This relationship can be represented as follows: m/m = m/Df An amorphic allele is commonly recessive to its wildtype counterpart. It is possible for an amorph to be dominant if the gene in question is required in two copies to elicit a normal phenotype (i.e. haploinsufficient). Hypomorph Hypomorphic describes a mutation that causes a partial loss of gene function. A hypomorph is a reduction in gene function through reduced (protein, RNA) expression or reduced functional performance, but not a complete loss. The phenotype of a hypomorph is more severe in trans to a deletion allele than when homozygous. m/DF > m/m Hypomorphs are usually recessive, but occasional alleles are dominant due to haploinsufficiency. ==Gain of function==

Hypermorph A hypermorphic mutation causes an increase in normal gene function. An antimorphic mutation might affect the function of a protein that acts as a dimer so that a dimer consisting of one normal and one mutated protein is no longer functional. Neomorph A neomorphic mutation causes a dominant gain of gene function that is different from the normal function. A neomorphic mutation can cause ectopic mRNA or protein expression, or new protein functions from altered protein structure. Changing wildtype gene dose has no effect on the phenotype of a neomorph. m/Df = m/+ = m/Dp == Isomorph ==

After Muller's classification of gene mutation, an isomorph was described as a silent point mutant with identical gene expression as the original allele. m/Df = m/Dp Therefore, with respect to the relationship between the original and mutated genes, one cannot talk about the effects of dominance and/or recessiveness. ==Overview==

;Muller's classification of mutant alleles ==References ==