Analysis of neocortex in three males with the fragile X syndrome

Authors

  • V. J. Hinton,

    1. Queens College and The Graduate School of The City University of New York
    2. The CSI/IBR Center for Developmental Neuroscience, North Shore University Hospital–Cornell University Medical College, Manhassett
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  • W. T. Brown,

    1. Department of Pediatrics, Division of Human Genetics, North Shore University Hospital–Cornell University Medical College, Manhassett
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  • K. Wisniewski,

    1. NY State Institute for Basic Research in Developmental Disabilities. Staten Island, New York
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  • Dr. R. D. Rudelli

    Corresponding author
    1. NY State Institute for Basic Research in Developmental Disabilities. Staten Island, New York
    • N.Y. State Institute for Basic Research, 1050 Forest Hill Road, Staten Island, NY 10314-3803
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Abstract

Fragile X [fraX] syndrome is a common hereditary disorder associated with a fragile site marker at Xq27.3 which clinically presents as a form of mental retardation (MR). Postmortem investigation of 3 fraX positive males with mild to moderate MR did not document any gross neuropathological changes. Golgi analysis of neocortical dendritic spine morphology extended our previous observations of immature, long, tortuous spines in one adult case of fraX (Rudelli, et al., Acta Neuropathologica 67:289–295, 1985) to 2 new cases. Evidence for similar dendritic spine abnormalities was found, although Golgi analysis was less than optimal because of incomplete dendritic stain impregnation. Neocortical intra-layer cell density was also investigated in all 3 cases. Cresyl violet stained neurons were counted in 10 randomly selected fields in neocortical layers II–VI of cingulate and temporal association areas (Brodmann's areas 23 and 38). Neuron counts in fraX and control neocortex showed no significant differences. Thus, abnormal dendritic spine morphology with preservation of neuronal density appears to characterize the neocortex in individuals with this common form of mental retardation.

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