An integrated route to identifying new pathogenesis-based therapeutic approaches for trisomy 21 (Down Syndrome) following the thought of Jérôme Lejeune.

Down Syndrome (DS) is the most frequent human chromosomal disorder. Main symptoms include intellectual disability (ID), cardiovascular defects and craniofacial dysmorphisms. Despite ID being measured by a test of symbolic logic skills, it is common for children with DS to arouse a climate of affective intensity greater than the norm. In 1959, Jérôme Lejeune (1926-1994) and coll. described an additional chromosome 21 (Hsa21) in children with DS (trisomy 21), giving origin to the field of medical genetics. Remarkably, the discovery of trisomy 21 had relevant social consequences for the affected children, in that their parents were no longer suspected to be alcoholics or infected with syphilis. Although it is broadly agreed that the DS phenotype originates from the altered expression of the genes located on Hsa21, its molecular pathogenesis is still unknown. To date, no therapy is recognized and recommended by guidelines as being effective in improving the cognitive abilities of persons with DS. The aim of this article is to categorize main therapeutical approaches or pathways to new approaches reported in the biomedical literature, to extract critical methodological points from the works of Lejeune and then to propose a new research project aimed to generate and integrate clinical, biochemical, genetic and bioinformatic data in order to identify novel therapeutic targets for this form of trisomy. We show here that nearly all the current lines of research were pursued, theorized or foreseen by Lejeune, and that central points of his method remain current: positive hypothesis about the existence of a solution, envision of systematic investigation of cell machinery, anchoring of clinical and biochemical finding to the chromosome physical map, and continuing clinical observation of the affected children. We therefore propose a project aimed at producing both experimentally and by meta-analysis state-of-the-art maps and databases related to clinical/phenotype, cytogenetics, exome, transcriptome, methylome, molecular biology, metabolome and mutations data. The primary expected outcome of this research project is the identification of a restricted list of strong candidate genes and mechanisms for ID in persons with DS in order to devise new rational therapeutic approaches.