Biological psychiatry / edited by Joseph Mendels.

  • Mendels, Joseph, 1937-
Date:
1973
Catalogue details

Licence: Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0)

Credit: Biological psychiatry / edited by Joseph Mendels. Source: Wellcome Collection.

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    MECHANISMS OF GENETIC CONTROL OF BEHAVIOR 7 ency of psychiatry to focus on the functional disorders (those without known organic etiologies) and to virtually exclude from its attention those psychological disorders with known somatic etiologies: for example, the mental deficiencies secondary to inborn errors of metabolism; the psy¬ choses associated with endocrinopathies or other metabolic diseases, gen¬ eral paresis, and many others. On the other hand, the extensive studies of the familial incidence of certain psychological disorders are strong evidence for the importance of genetic factors, thus somatic factors in etiology. Most recent have been the studies of familial incidence of psychological disorders in the biological and adoptive families of schizophrenic patients who had been adopted early in life. These provide strong evidence for the impor¬ tance of genetic factors in the etiology of schizophrenia and are perhaps the most conclusive evidence for the role of somatic factors in the etiology of any functional disorders (Kety, et al., 1968; Heston and Denney, 1968). MECHANISMS OF GENETIC CONTROL OF BEHAVIOR Over the past two decades the elucidation of the molecular mechanisms of genetics has been one of the outstanding areas of progress of the bio¬ logical sciences. In relation to medicine, the most striking progress has been made in the understanding of those diseases of metabolism that are the result of specific enzyme defects of an hereditary nature which are de¬ tectable in certain tissues of the infant or the adult. Modern knowledge has developed from the now classical concept of Garrod, who in 1908 pointed to the existence of inborn errors of metabolism. At the present time there are well over 100 known examples of inborn errors of metabolism and many conform to the hypothesis put forth by Beadle in 1945, one-gene- one-enzyme. Over 25% of these metabolic diseases include mental retar¬ dation or other behavioral abnormalities among their clinical manifesta¬ tions. Even so, only a few percent of mental retardates can be demon¬ strated to have one of these identifiable diseases (Hsia, 1967). It has naturally been the hope of investigators in biological psychiatry that within the syndromes of central concern to psychiatry (e.g., schizo¬ phrenia) cases would be found that were manifestations of genetically de¬ termined enzyme defects. To date, outside the area of mental retardation, simple enzyme defects have not been found; and modern genetic theory would not predict that enzyme defects need necessarily be found in adults manifest¬ ing genetic disorders. Genes are now generally classified into two major types : structural and regulatory. It is the structural genes that carry the coding for protein synthesis and abnormalities in such genes may result in enzyme de-