The medical utility of genomics data in neuropsychiatry: mutational genetics versus association genetics

Functionally gene-linked polymorphic regions and genetically controlled neurotransmitters metabolism

In clinical psychopharmacology, the existence of marked inter-individual differences in both outcome and side effects is a common observation. Consequently, pharmacogenetics has also gained an increasing interest in psychiatry. Recent exciting findings seem to suggest that the growing interest in regulatory regions of candidate genes and neurotransmitters metabolism, together with the application of sophisticated molecular approaches, may offer new opportunities in neuropsychopharmacology. Indeed, quantitative variation of gene expression and/or of neurotransmitters metabolism could better explain both psychopathology and clinical response to psychotropic drugs. Three functional polymorphisms, and their possible relationship with clinical variables, are discussed. The first is the 44-bp insertion/deletion reported in the promoter region of the serotonin transporter gene. A functional repeat polymorphism in the promoter region of the gene encoding for the enzyme monoamine oxidase A represents the second example. The last is a functional polymorphism within the coding region of the gene encoding for the enzyme catechol-O-methyltransferase

Applied neurogenomics

Neurogenomics, the study of the genes of the nervous system, has applications in basic research, in the pharmaceutical industry and in the management of neurological disorders. Basic research applications include molecular neuropathology, the detection of genes for neurological disorders, the study of gene expression in the CNS and creation of transgenic models of neurological disorders. Pharmaceutical applications may be in the areas of molecular neuropharmacology, the discovery of new drugs for neurological disorders, gene therapy and the development of personalised medicines based on pharmacogenomics. Clinical applications in neurology include the redefinition and reclassification of diseases, molecular diagnostics and the integration of diagnostics with therapeutics. Various methods for the study of genes and gene expression are described. Genes have been identified for only a limited number of neurological disorders so far. The discovery of genes defective in neurological disorders would facilitate drug discovery, molecular diagnostics and gene therapy diseases. There is a trend towards the integration of diagnosis, genetic screening, prevention, treatment and monitoring of therapy of neurological disorders, which will be facilitated by neurogenomics. Pharmacogenomics-based personalised medicines are anticipated to be part of medical practice by the end of the first decade of the 21st century, and neurogenomics will contribute to the development of personalised medicines for diseases of the CNS.

Variations of the mononucleotide and short oligonucleotide distributions in the genomes of various organisms

We calculated the variation coefficients of the mononucleotide and short oligonucleotide distributions in over 1700 long genomic sequences originating from six organisms to demonstrate that the human and Escherichia coli genomic sequences were the least and the most uniform, respectively. The most non-random genomic distributions were exhibited by the four canonical nucleotides, followed by the strong and weak nucleotides, while the distributions of purine or pyrimidine nucleotides and especially the distributions of (A+C) and (G+T) were significantly more uniform even in the human genome. In the human and mouse genomes, the highest coefficients of variation were further observed with the oligonucleotides where CG was combined with the strong nucleotides while its combination with the weak nucleotides significantly decreased the variation which, however, was still very high. High variation was also exhibited by the remaining oligonucleotides composed exclusively of the strong nucleotides or those containing only weak nucleotides. On the other hand, the distributions of oligonucleotides containing similar and especially the same numbers of the strong and weak nucleotides, but no CG or TA dinucleotide, were the most uniform. The information following from the present analysis will be useful not only in the identification of important genomic regions but also in computer simulations of the genomic nucleotide sequences in order to trace and reproduce the pathways of genome evolution.