The development of genetic sex determination and cytologically distinct sex chromosomes leads to the potential problem of gene dosage imbalances between autosomes and sex chromosomes and also between males and females. To circumvent these imbalances, mammals have developed an elaborate system of dosage compensation that includes both upregulation and repression of the X chromosome. Recent advances have provided insights into the evolutionary history of how both the imprinted and random forms of X chromosome inactivation have come about. Furthermore, our understanding of the epigenetic switch at the X-inactivation center and the molecular aspects of chromosome-wide silencing has greatly improved recently. Here, we review various facets of the ever-expanding field of mammalian dosage compensation and discuss its evolutionary, developmental, and mechanistic components.

中文翻译：

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X染色体剂量补偿：哺乳动物如何保持平衡。

遗传性别决定和细胞学上不同的性染色体的发展导致常染色体和性染色体之间以及男性和女性之间基因剂量失衡的潜在问题。为了避免这些不平衡，哺乳动物已经开发出精心设计的剂量补偿系统，其中包括X染色体的上调和抑制。最近的进展提供了有关X染色体灭活的印迹形式和随机形式是如何产生的进化历史的见解。此外，我们对X灭活中心的表观遗传开关和全染色体沉默分子方面的了解最近有了很大的提高。在这里，我们回顾了哺乳动物剂量补偿领域不断扩展的各个方面，并讨论了其进化，发展，