Monosomy for the X chromosome.
Dosage compensation serves to equalize X chromosome gene expression in mammalian males and females and involves extensive silencing of the 2nd X chromosome in females. If dosage compensation mechanisms completely suppressed the 2nd X chromosome, then actual physical loss of this "eXtra" chromosome should have few consequences. However, X monosomy has major effects upon normal development, fertility and longevity in humans and some other species. This article reviews observations and arguments attempting to explain the phenotypic effects of X monosomy in humans and other mammals in terms of X chromosome gene dosage.
Bondy
Carolyn A
CA
Developmental Endocrinology Branch, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA. bondyc@mail.nih.gov
Cheng
Clara
C
D000782:Aneuploidy; D000818:Animals; D004303:Dosage Compensation, Genetic; D006239:Haplotypes; D006801:Humans; D009006:Monosomy; D014960:X Chromosome; D049951:X Chromosome Inactivation