Frontiers in Bioscience-Landmark (FBL) is published by IMR Press from Volume 26 Issue 5 (2021). Previous articles were published by another publisher on a subscription basis, and they are hosted by IMR Press on imrpress.com as a courtesy and upon agreement with Frontiers in Bioscience.
This review on the genes implicated in mental retardation, and its X-chromosome linked forms, we presented at the symposium 'The Regulation of Gene Expression in the Brain' (January 23-26, 2003, Heron Island Australia). The main purpose of the review was to highlight the current knowledge of the spectrum of the genes causing mental retardation, provide an insight in to their function(s), where known, and to speculate about the evolutionary processes which shaped such an unexpected concentration of these genes on the human sex chromosome X. Such genes with naturally occurring mutations provide an invaluable opportunity for identifying the pathways essential for the normal function of the brain. Once identified, cellular and animal models can then be used for experimentation