Abstract

The fact that there is a phenomenon of dosage compensation for the euchromatin part of the genome in eukaryotes has been known for almost a seventy years. This phenomenon is currently being studied under the name epigenetic control of gene expression. Evidence for the existence of dosage compensation at the gene level is obtained from genes localized on the sex chromosomes, the most famous example of which is the X-chromosome inactivation in mammals. As for genes localized on autosomes, there are no convincing data on this score. The question of whether there is a dosage compensation for the heterochromatic part of the genome in eukaryotes remains open. We have data indicating the existence of dosage compensation for the heterochromatin part of the human genome, using the example of chromosomal Q-heterochromatin regions (Q-HRs). It turned out that this phenomenon manifests itself both in sex chromosomes and in autosomes, regardless of gender, age, racial-ethnic origin and climatogeographical characteristics of the place of permanent residence of a human. Moreover, this process is associated with an important part of human life (maintaining temperature homeostasis) and has a phenotypic manifestation, which can be objectively studied. The question is discussed whether the phenomenon of chromosomal heterochromatin dosage compensation should be considered as an example of epigenetics, or it is a different phenomenon, since it does not affect genes?

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