What is the biological significance of allelic gene exchange between homologous chromosomes?

The phenomenon of allelic gene exchange between homologous chromosomes has helped scientists determine the location of each gene in the chromosome, i.e., build genetic maps. The genetic map of the chromosome is a diagram of the mutual arrangement of genes located on the same chromosome, i.e. in the same linkage group. The construction of such maps is of great interest both for basic research and for solving a wide variety of practical problems. For example, genetic maps of human chromosomes are very important for the diagnosis of a number of serious hereditary diseases. Currently, simple genetic maps are being replaced by molecular genetic maps that contain information about the nucleotide sequences of genes.