The number of diabetic patients will be doubled in the coming decades reaching 300 million for year 2025. The number of type 1 diabetics will also be increased but the majority of it will result from the increased number of type 2 diabetics. All types of diabetes are the consequence of a combination of genetic susceptibility and environmental factors, meaning that the prevention of diabetes epidemic cannot be done without the clarification of the genetic background. Significant progression has happened in the discovery of the genetic background of type 1 diabetes mellitus. It was helped by the etiologic classification of the disease: with the new classification the patient groups became more homogeneous. The HLA system is responsible for about 50-70% of the genetic risk while the effects of other genetic factors contribute 1-2% of the genetic susceptibility, respectively. Presently 25 gene regions are known as the different genetic factors of type 1 diabetes mellitus. Regarding the HLA system, the genes and pathomechanism causing the disease are not known. The classification of diabetes mellitus can be based on the HLA type while the predictability of type 1 diabetes mellitus is helped by the HLA type and the INS-VNTR. Much less is known about the genetic background of the polygenic type 2 diabetes mellitus. Its manifestation is now happening at younger age before. The best-fit genetic model consists of only a few genes with moderate effect superimposed on a polygenic background. Several "candidate" genes participating in the impaired insulin secretion and insulin action have already been investigated as the genes responsible for type 2 diabetes. These data showed the specificity in the population and most showed mild or modest association with the disease. Genomewide scans have resulted a number of significant diabetes susceptibility genes specific for a variety of populations, but these investigations have only resulted in the isolation of one gene (calpain 10) that is thought to contribute to type 2 diabetes. Most recent genomewide scans found loci on chromosome 20 in two different populations with significant segregation of type 2 diabetes. These loci are near to the region harboring the transcription factor hepatocyte nuclear factor genes. The transcription regulator HNF family is responsible for the regulation of the expression of several genes participating in the function of liver and pancreatic islet becoming a strong candidate for being a diabetes gene.
|Translated title of the contribution||The genetics of diabetes mellitus|
|Number of pages||11|
|Journal||Lege Artis Medicinae|
|Publication status||Published - Jul 1 2004|
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