Abstract
Mental retardation (MR) and hypotonia occur together frequently and have a heterogeneous etiology. Molecular and clinical studies have led to the recent discovery of genes on the X chromosome that may be associated with syndromal forms of X-linked MR (XLMR). These disorders manifest additional neurological and somatic features that are helpful in establishing a specific diagnosis and etiology. This article provides an overview of MR and its association with hypotonia, with a review of five 'new' XLMR-hypotonia syndromes.
MeSH terms
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Child
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Chromosomes, Human, X*
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Humans
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Membrane Transport Proteins / deficiency
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Mental Retardation, X-Linked / genetics*
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Methyl-CpG-Binding Protein 2 / genetics
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Monocarboxylic Acid Transporters / genetics
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Muscle Hypotonia / genetics*
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Muscle Spasticity / genetics
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Mutation
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Nerve Tissue Proteins / genetics
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Plasma Membrane Neurotransmitter Transport Proteins / genetics
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Sex Chromosome Disorders / diagnosis*
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Sex Chromosome Disorders / genetics
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Spermine Synthase / deficiency
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Symporters
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alpha-Thalassemia / diagnosis
Substances
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MECP2 protein, human
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Membrane Transport Proteins
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Methyl-CpG-Binding Protein 2
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Monocarboxylic Acid Transporters
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Nerve Tissue Proteins
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Plasma Membrane Neurotransmitter Transport Proteins
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SLC16A2 protein, human
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SLC6A8 protein, human
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Symporters
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creatine transporter
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Spermine Synthase