Epimutations of imprinted genes in the human genome: Classification,causes, association with hereditary pathology

Genomic imprinting is an epigenetic phenomenon characterized by monoallelic expression of the genes depending on their parental origin. The molecular basis of this expression is covalent modifications of DNA and histones that are formed during maturation of germline cells. Abnormalities of the establishment of genomic imprinting during gametogenesis or its maintenance at various stages of development, caused by aberrant epigenetic modifications of the chromatin, predominantly disturbance of DNA methylation state, are a form of mutational variability of imprinted genomic loci. In this review, we consider the spectrum of epimutations of imprinted genes, present their classification, and discuss possible causes of their appearance and their role in etiology of hereditary human diseases.