The neuropsychiatry and multisystem features of the Smith-Magenis Syndrome: A review
ABSTRACT Smith-Magenis Syndrome (SMS) is a complex, pediatric, neurobehavioral, contiguous gene syndrome ascribed to interstitial microdeletion of chromosome 17, band 11.2. The syndrome is characterized by distinctive behavioral, neurocognitive, and neuropsychiatric abnormalities. This genetically mediated disorder of mental retardation prompts behavioral researchers to examine the links between genes, brain, and behavior in order to solve the gene-behavior puzzle and the genotype/phenotype correlation. In this article, the authors review literature on behavioral profile and its associated psychopathologies, cognitive profiles, multisystem abnormalities, and genetic correlates that highlight the complexities of the disorder.
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ABSTRACT: Systematic data regarding early neurodevelopmental functioning in Smith-Magenis syndrome are limited. Eleven children with Smith-Magenis syndrome less than 3 years of age (mean, 19 months; range, 5-34 months) received prospective multidisciplinary assessments using standardized measures. The total sample scored in the moderately to severely delayed range in cognitive functioning, expressive language, and motor skills and exhibited generalized hypotonia, oral-motor abnormalities, and middle ear dysfunction. Socialization skills were average, and significantly higher than daily living, communication, and motor abilities, which were below average. Mean behavior ratings were in the nonautistic range. According to exploratory analyses, the toddler subgroup scored significantly lower than the infant subgroup in cognition, expressive language, and adaptive behavior, suggesting that the toddlers were more delayed than the infants relative to their respective peers. Infants aged approximately 1 year or younger exhibited cognitive, language, and motor skills that ranged from average to delayed, but with age-appropriate social skills and minimal maladaptive behaviors. At ages 2 to 3 years, the toddlers consistently exhibited cognitive, expressive language, adaptive behavior, and motor delays and mildly to moderately autistic behaviors. Combining age groups in studies may mask developmental and behavioral differences. Increased knowledge of these early neurodevelopmental characteristics should facilitate diagnosis and appropriate intervention.Pediatric Neurology 10/2009; 41(4):250-8. DOI:10.1016/j.pediatrneurol.2009.04.015 · 1.50 Impact Factor
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ABSTRACT: Genomic sister-disorders are defined here as diseases mediated by duplications versus deletions of the same region. Such disorders can provide unique information concerning the genomic underpinnings of human neurodevelopment because effects of diametric variation in gene copy number on cognitive and behavioral phenotypes can be inferred. We describe evidence from the literature on deletions versus duplications for the regions underlying the best-known human neurogenetic sister-disorders, including Williams syndrome, Velocardiofacial syndrome, and Smith–Magenis syndrome, as well as the X-chromosomal conditions Klinefelter and Turner syndromes. These data suggest that diametric copy-number alterations can, like diametric alterations to imprinted genes, generate contrasting phenotypes associated with autistic-spectrum and psychotic-spectrum conditions. Genomically based perturbations to the development of the human social brain are thus apparently mediated to a notable degree by effects of variation in gene copy number. We also conducted the first analyses of positive selection for genes in the regions affected by these disorders. We found evidence consistent with adaptive evolution of protein-coding genes, or selective sweeps, for three of the four sets of sister-syndromes analyzed. These studies of selection facilitate identification of candidate genes for the phenotypes observed and lend a novel evolutionary dimension to the analysis of human cognitive architecture and neurogenetic disorders.Evolutionary Applications 01/2009; 2(1):81 - 100. DOI:10.1111/j.1752-4571.2008.00056.x · 4.57 Impact Factor