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Mental Retardation: Is It in the Genes?

Mental Retardation and Developmental Delay: Genetic and Epigenetic Factors, by Moyra Smith. 2006. New York: Oxford University Press, 344 pp., $49.95 (HB). Most of us have had the experience of evaluating a child who looks just like other children, whose MRI scan is read as normal, and whose test performance results in a diagnosis of mental retardation. Such children cause us to ponder the question, “How can a brain look so normal, yet work so abnormally?” As the results are presented, parents ponder a different question. They want to know why this has happened to their child. What makes the question a hard one to respond to is that we ask ourselves the same question but often do not have an answer. The neuropsychological conceptualization of mental retardation starts with skill patterns and works backwards through neural networks looking for cause. Mental Retardation and Developmental Delay: Genetic and Epigenetic Factors begins with the inner workings of the cell, examining genes, gene products, and cell metabolism as the basis for the observed disruption of learning and memory.