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Pathogenesis of mental deficiency in trisomy 21
1Centre de Recherches Claude Bernard, Génétique Humaine et Maladies de l'Intelligence, Institut de Progenèse, Paris, France.
Abstract:
In trisomy 21, pathogenesis of mental retardation is still poorly understood although the knowledge of the genic content of chromosome 21 is steadily increasing. Short of discovering how to silence selectively one of the 3 chromosomes 21, no rational medication can be envisaged before pathogenesis has been unraveled, at least partially. A biochemical scheme of impairment of mental efficiency is presented. Secondarily, the possible deleterious effects of a given gene overdose are discussed. Cu/Zn SOD, cystathionine beta synthase, S 100 beta protein, phosphofructokinase, purine synthesis and adenosine pharmacology, thyroid disturbance, and elevated TSH with low rT3 as well as biopterine metabolism interferences are reviewed. It is observed that the metabolic paths controlled by these genes, although unrelated at first glance, are in fact tightly related by their effects, just as if synteny was in some way related to biochemical cooperation or mutually controlled regulation. Experiments in vitro have demonstrated a peculiar sensitivity of trisomic 21 lymphocytes to methotrexate. From this starting point, systematic research of special sensitivities has begun. Clinical observations and relevant statistical methods allow study of the speed of mental development under various medications. The interest of regulating thyroid metabolism, when needed, is exemplified. Reequilibration of monocarbon metabolism is discussed and the seemingly favourable effect of folinic acid medication in pseudo-Alzheimer complication is presented.
Insights
Understanding Down syndrome's mental impairment is key. This study explores biochemical pathways and gene dosage effects, suggesting targeted metabolic interventions like folinic acid may help manage cognitive decline in trisomy 21.
Area of Science:
- Biochemistry
- Genetics
- Neuroscience
Background:
- Pathogenesis of mental retardation in trisomy 21 remains poorly understood despite increasing knowledge of chromosome 21's genetic content.
- A biochemical framework for mental efficiency impairment in trisomy 21 is proposed.
- The study reviews potential deleterious effects of gene overdose from chromosome 21.
Purpose of the Study:
- To present a biochemical scheme of mental efficiency impairment in trisomy 21.
- To discuss the effects of gene overdose from chromosome 21.
- To explore potential therapeutic interventions targeting metabolic pathways.
Main Methods:
- Review of metabolic pathways affected by genes on chromosome 21, including Cu/Zn SOD, cystathionine beta synthase, S 100 beta protein, phosphofructokinase, purine synthesis, and biopterine metabolism.
- In vitro experiments demonstrating sensitivity of trisomic 21 lymphocytes to methotrexate.
- Clinical observations and statistical analysis of mental development under various medications.
Main Results:
- Identified interrelations between metabolic pathways affected by trisomy 21 genes, suggesting biochemical cooperation or regulation.
- Observed specific sensitivities in trisomic 21 lymphocytes, notably to methotrexate.
- Demonstrated potential benefits of regulating thyroid metabolism and using folinic acid in pseudo-Alzheimer complications.
Conclusions:
- Metabolic pathways affected by trisomy 21 genes are interconnected, offering targets for intervention.
- Identifying specific sensitivities in trisomic cells can guide therapeutic strategies.
- Metabolic interventions, such as thyroid regulation and folinic acid, show promise for managing cognitive and developmental aspects of trisomy 21.