Spine Morphology and Plasticity in X-linked Mental Retardations

In the past several years, a multitude of genes has been linked to mental retardations in humans, in particular the most commonly occurring X-linked mental retardations. An emerging idea is that structural and functional abnormalities in spines and synapses are a common feature of mental retardations. Consistent with this concept, a number of genes that control synaptic function have been implicated in X-linked mental retardations. In this review we discuss aberrations in spine and synapse structure and function in X-linked human mental retardations and corresponding mouse models with mutations in genes that modulate synaptic structure and function. A thorough understanding of these synaptic structures and abnormalities would enhance our knowledge of the normal process of learning and understand how synaptic aberrations contribute to cognitive deficits such as those observed in mental retardations.