Linkage analysis in informative families for the identification of disease genes in the post-genoma era

During the last few years, the identification and characterization of disease genes has become the main approach to understanding the role of specific genes in the pathogenesis of inherited disorders. Several strategies have been developed to identify novel disease genes. As the Human Genome Project finishes off the sequence of the human genome and the 30000-35000 genes estimated to be present in our genome are identified, the "positional candidate gene approach" will be the elective strategy in the correlation of a gene with a specific clinical phenotype. In the positional candidate gene approach, the genetic mapping of a locus is the first step for searching a disease gene. In fact, when a new disease gene is assigned to a specific locus in the genome, it will be easy to search in the database the genes isolated from the same region which will be candidate as responsible for the disorder. In this respect, the collection of informative families with recurrence of specific genetic disorders in one hand and the genetic mapping of these inherited diseases on the other hand assume a relevant importance in order to identify new disease genes.