Post Mendelian Discoveries

Gene interaction is the influence of alleles and nonalleles ion the normal phenotypic expression of genes. It is two types, intragenic (allelic) and intergenic (nonallelic). In the intragenic interaction the two allels (present on the same gene locus on the two homologous chromosome) of a gene interact in such a way as to produce a phenotypic expression different from typical dominant-recessive phenotype, $e \cdot g$., incomplete dominance, codominance, multiple alleles.

In intergenic or non-allelic interaction, two or more independent gene present on the same or different chromosomes interact to produce different expression, $e . g .$, epistasis, duplicate genes, complementary genes, supplementary genes, lethal genes, inhibitory genes, etc.