2012/09/15 by Christine M. Distèche · 1 citation
Biochemistry, Genetics and Molecular Biology · Agricultural and Biological Sciences · #Genetic and Clinical Aspects of Sex Determination and Chromosomal Abnormalities #CRISPR and Genetic Engineering #Chromosomal and Genetic Variations
paper · doi:10.1146/annurev-genet-110711-155454
openalex publication_date 2012/09/15 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/16
Differentiated sex chromosomes evolved because of suppressed recombination once sex became genetically controlled. In XX/XY and ZZ/ZW systems, the heterogametic sex became partially aneuploid after degeneration of the Y or W. Often, aneuploidy causes abnormal levels of gene expression throughout the entire genome. Dosage compensation mechanisms evolved to restore balanced expression of the genome. These mechanisms include upregulation of the heterogametic chromosome as well as repression in the homogametic sex. Remarkably, strategies for dosage compensation differ between species. In organisms where more is known about molecular mechanisms of dosage compensation, specific protein complexes containing noncoding RNAs are targeted to the X chromosome. In addition, the dosage-regulated chromosome often occupies a specific nuclear compartment. Some genes escape dosage compensation, potentially resulting in sex-specific differences in gene expression. This review focuses on dosage compensation in mammals, with comparisons to fruit flies, nematodes, and birds.