[Molecular cytogenetic studies of chromosomal abnormalities and disorders in nervous and mental diseases: search for biological markers for diagnosis].

Molecular cytogenetic and cytogenetic studies of chromosomal disorders in patients with nervous and mental disorders were conducted using currently available approaches, including fluorescence in situ hybridization (FISH) with an original collection of centromeric, telomeric, region-specific DNA probes. A novel in situ hybridization protocol for rapid (15-30 min) chromosomal detection procedure and directly fluoresceinated DNA probes are recommended for use in mental retardation and congenital malformations. Chromosomal abnormalities could be detected in postnatal cases with chromosomal structural rearrangements, aneuplodies of gonosomes (including mosaicisms) and autosomes (including marker chromosomes). Molecular cytogenetics (or FISH diagnosis) can be used when classical cytogenetic methods are insufficient. The authors' experience shows that FISH should be utilized only as an adjunctive test for classical cytogenetic studies when banding techniques are ineffective; cytogenetic methods should be utilized for the preclinical diagnosis of Rett's syndrome. Detection by original probes gives an additional possibility in FISH analysis. Molecular cytogenetic methods are shown to provide a rapid accurate approach to studying and diagnosing chromosomal anomalies and disorders in mental retardation with congenital malformations and Rett's syndrome in children and to exploring aneuploidies in the postmortem cell samples from schizophrenic patients.