Complex approaches to study complex trait genetics in multiple sclerosis.

Multiple sclerosis (MS) is a complex trait disorder defined by several genes and their interactions with environmental factors. A comprehensive exploration of the susceptibility variants had not been feasible until recently when new developments in biotechnology and bioinformatics made possible sequencing of the whole human genome, cataloguing of nucleotide variants and alignments of these variants in haplotypes. Earlier observations from epidemiological, candidate gene and linkage studies provided ample evidence to support a complex genetic determination of MS. New biotechnology and bioinformatics resources have been recently applied to further successful explorations of the disease. These efforts were paralleled by more careful and reliable ascertainments of disease phenotypes, collaborations among specialized centers to generate sufficient sample size and involvement of clinician-scientists capable of working both on the clinical and scientific study sides. Data obtained from the whole genome association studies (GWAS) elevated our understanding of MS genetics to a new level by identifying an extensive list of genetic determinants. Pathway analyses of MS-associated variants provided evidence to support the immune etiology of the disease. Future research will likely explore how environmental factors interact with the genome, and contribute to the abnormal immune activation and inflammation. This review summarizes the outcomes of MS genetic explorations including those of recent GWAS, and highlights practical consequences of genetic and genomic studies by pointing out as to how the derived data facilitate further elucidation of MS pathogenesis. A better understanding of disease processes is necessary for future advancements in therapeutics and the development of disease prevention strategies.