MCV/Q, Medical College of Virginia Quarterly

MCV/Q, Medical College of Virginia Quarterly


Walter E. Nance

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MCV/Q, Medical College of Virginia Quarterly





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Human geneticists are often accused of being preoccupied with exotic syndromes that are of marginal relevance to the general population. Brilliant success has been achieved during the past two decades in defining the nature and function of the genetic material, the molecular pathology of a large number of metabolic diseases, the phenotype of more than 2,000 Mendelian traits, and more recently the chromosomal location of a rapidly expanding number of human gene pairs. In contrast, relatively little progress has been made in the genetic analysis of quantitative traits such as blood pressure, serum cholesterol, intelligence quotient, skin color, height, birth weight, or glucose tolerance. Traits of this type are not only of interest to society, but may also relate significantly to a variety of common diseases. With almost every continuously distributed quantitative trait, single gene defects have been identified which can profoundly alter the phenotype. For example, the single gene pairs which determine albinism and Tay-Sachs disease can profoundly alter skin color and IQ respectively. However, the causes of less extreme variation can be exceedingly complex, resulting from the cumulative effects of many gene pairs and their interactions with each other and with the environment. Nevertheless, even if the effects of individual gene pairs cannot be identified, the source of the observed variation may often be inferred from an analysis of the phenotypic correlation of relatives of various degree. Twin studies have been widely used in the past to gain insight into the inheritance of quantitative traits, and with the support of a Program Project Grant from the National Institute of Maternal and Child Health, the Department of Human Genetics at the Medical College of Virginia has become a leader in the use of twins for biomedical research.


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