Progress in pediatric neurology.

A central part of Pediatric Neurology is currently dominated by the search for genetic factors involved in developmental disorders of the nervous syst em, including cases where the cytogenetic examination remains uncontributiv e. The prerequisite for a good definition of the malformative phenotypes le ads to distinguish: 1 cerebral malformations that can be identified at the macroscopic scale, by imaging 2 polymalformative syndromes including mental retardation where cerebral imaging is not contributive, thus the syndromat ic definition is based on associated somatic anomalies. 3 Non-syndromatic m ental retardation, where a genetic origin is clear only in the familial for ms. Various methodological approaches have included genetic linkage studies , search for inframicroscopic chromosomal rearrangements in the critical re gion and investigation of candidate genes. A great number of syndromes have been connected with a great diversity of genetic mechanisms, whose many ex amples are presented: genopathies with regular or Variable expression, unst able mutations, contiguous gene syndromes or other complex infracytogenetic rearrangements, chromosomal or genic mosaicisms, mutations submitted to pa rental imprinting... New methods of genomic screening will be necessary to progress in this field given the great number of genes involved in cerebral development. As for the early developmental disorders of the PNS and muscl e, their diagnosis becomes frequent during the intrauterine life, raising t he problem of a better definition of the fetopathological phenotypes.