On the mechanism of mental deficiency in chromosomal diseases

Three ways are used to study the relations between mental deficiency and chromosomal diseases. 1 Pharmacological approach shows a peculiar sensitivity of the cholinergic system in trisomic 21 children. A trouble in the manufacture of cholinergic mediator is plausible. 2 General biochemistryshows a slight shift of the glycolytic pathway in trisomics 21 as well as some localised abnormalities of amino acids. 3 Gene mapping allows the localisation of the main responsible genes on band q22.1, and among them the gene coding for superoxide dismutase-1. Also glutathion peroxidase is elevated. These disparate facts are discussed in the light of a model of the machinery regulating the production of chemical mediators. Comparison with other diseases lead to the hypothesis that rather simple and localised mechanisms could be specially important.