A longstanding project in the laboratory has been the search for genes causing specific reading disability (dyslexia). This work has been done largely in collaboration with the Colorado Learning Disabilities Research Center, and NIH-funded Center for Learning Disabilities research based at the Institute for Behavior Genetics at the University of Colorado in Boulder (http://www.nichd.nih.gov/research/supported/ldrc.cfm). Collaborators include Drs. John DeFries, Richard Olson, Bruce Pennington, Erik Willcutt, Sally Wadsworth, and Barbara Wise. Through this collaboration, we identified two chromosomal regions linked to dyslexia on chromosome 15 and chromosome 6. These linkages have been replicated by other laboratories world-wide and candidate genes have been identified (for review see McGrath et al., 2006). At least 10 other chromosomal regions have also been identified as candidates. Since several reading, language, speech, and learning disorders appear to overlap in children and in their families, a current focus in our laboratory is to see if these overlaps (comorbidity) are due at least in part to the influences of the same genes. We are studying families with Speech Sound Disorder with Dr. Bruce Pennington at the University of Denver, and our results show that these disorders also show linkage to the same regions of chromosome 6 and 15 that contain genes influencing reading disability (Smith et al., 2005). We are working on similar studies on Specific Language Impairment with Dr. Mabel Rice at the University of Kansas in Lawrence. Studies of ADHD have been done with Drs. Christopher Kratochvil, David Bylund, Jean Deupree, and Cynthia Ellis) which confirmed the gene ADRA2A as an influence on ADHD and on the activity of the receptor, and studies with Dr. Erik Willcutt have indicated that additional influences on ADHD come from genes in the chromosome 6 linkage region for dyslexia.
Representative Publications
Smith, S.D. (2007) Genes, language development, and language disorders. Ment Retard Dev Disabil Res Rev. 2007;13(1):96-105.
Peterson, R.L., McGrath, L.M., Smith S.D., Pennington, B.F. (2007) Neuropsychology and genetics of speech, language, and literacy disorders. Pediatr Clin North Am. 54(3):543-61.
Smith, S.D., Gilger, J.W. (2007) Dyslexia and Other Specific Learning Disorders. In Rimoin, David L., Conner, J. Michael, Pyeritz, Reed E., Korf, Bruce R., and Emery, Alan E.H., (Eds), Emery and Rimoin's Principles and Practice of Medical Genetics, 4th Ed., New York, Elsevier. Pp 2548-2568.
Shelley Smith
Professor of Pediatrics
University of Nebraska Medical Center
