The Application Of Next Generation Sequencing For Detection Of MODY Pathogenic Genes

ObjectiveMonogenic diabetes is a rare disease, caused by a change in a single gene, accounts for1-2%of diabetes. The most prevalent phenotype is maturity onset diabetes of the young (MODY). MODY is characterized by dominant inheritance of early-onset, non-insulin dependent diabetes, and is often misclassified as type1or type2diabetes. The term MODY describes a heterogeneous group of disorders caused by mutations in genes important to beta cell development, function and regulation, glucose sensing, and in the insulin gene itself. Mutations in13different genes can cause MODY, for example, INS, HNF1A,HNF4A,GCK and so on. The expected clinical course, complications and associated extra-pancreatic features vary based upon the underlying molecular genetic defects. Correctly identifying MODY has important implications for treatment, surveillance of complications and associated extra-pancreatic disorders, and identification of affected and at-risk family members. However, approximately10%to20%of MODY families remain genetically unexplained.Due to the application of target region sequencing technology, the research of monogenic diseases has made a great breakthrough. A target region is comparatively smaller than the whole exoms, and as such partners can spend less and get more information for the region of interest. In addition, target region sequencing can also focus on non-coding regions and is suitable for case/control studies with large sample sizes. Target region sequencing is more flexible and has become a highly powerful and efficient strategy for identifying novel causative genes for not only monogenic but also complex disorders. The purpose of this research is to explore the unknown responsible genes of monogenic diabetes by investigating those regions associated with beta cell function and, metabolism.Materials and Methods1. Selection of appropriate patients for target region sequencingFirst we used Sanger sequencing to analyze the variations of responsible genes based on clinical informations, such as GCK, HNF1A, HNF4A and KCNJ11. After excluding twelve families with mutations, we chose32patients from different families with typical manifestations for target region sequencing.2. Data analysisWe postulated that unknown genes are related to beta cells. reviewing all the genes mutations that have been founded, and according to the variations of these genes in other family members, we found the candidate gene.3. ValidationAfter we got the candidate gene, we did a further research about its structure and function. Meanwhile we completed clinical manifestations and chemical examinations related to this gene.ReaultsAfter analyzing all the variations in the32patients, we thought UCP3was probably the new responsible gene of MODY. Further research in NCBI revealed that this gene encodes a uncoupling protein in mitochondrial inner membrane, which could uncouples the oxidative phosphorylation from adenosine-5’-triphosphate synthesis, facilitate the transfer of protons and protect mitochondria against lipid-induced oxidative stress. The gene for UCP3have been investigated for polymorphism and mutations, and its impact on Type2diabetes, obesity and body weight gain or body mass index have been studied with varying results reported.ConclusionThe research is aimed to find unknown responsible genes of monogenic diabetes using target region sequencing. After analyzing the data got from32families, we found the candidate gene UCP3, which is involved in the process of metabolism, but its function remains to be validated in further research. And this study suggests that target region sequencing is a useful tool in the research of genetic area.