Identical or similar phenotypes, traits, disorders, caused by different genetic or environmental mechanisms. Genetic heterogeneity The presence of different alleles at a gene locus. 2 The ability of more than one allele to cause the same trait, phenotype or disease. Alleles at different gene loci (locus heterogeneity), as well as those at the same locus, expressed as the same trait.

SOURCE: cat-world.com.au