Gene expression profiles stratified according to type 1 diabetes mellitus susceptibility regions

The MHC region (6p21) aggregates the major genes that contribute to susceptibility to type 1 diabetes (T1D). Three additional relevant susceptibility regions mapped on chromosomes 1p13 (PTPN22), 2q33 (CTLA-4), and 11p15 (insulin) have also been described by linkage studies. To evaluate the contribution of these susceptibility regions and the chromosomes that house these regions, we performed a large-scale differential gene expression on lymphomononuclear cells of recently diagnosed T1D patients, pinpointing relevant modulated genes clustered in these regions and their respective chromosomes. A total of 4608 cDNAs from the IMAGE library were spotted onto glass slides using robotic technology. Statistical analysis was carried out using the SAM program, and data regarding gene location and biological function were obtained at the SOURCE, NCBI, and FATIGO programs. Three induced genes were observed spanning around the MHC region (6p21-6p23), and seven modulated genes (5 repressed and 2 repressed) were seen spanning around the 6q21-24 region. Additional modulated genes were observed in and around the 1p13, 2q33, and 11p15 regions. Overall, modulated genes in these regions were primarily associated with cellular metabolism, transcription factors and signaling transduction. The differential gene expression characterization may identify new genes potentially involved with diabetes pathogenesis.

Is HLA Class II Profile Relevant for the Study of Large-Scale Differentially Expressed Genes in Type 1 Diabetes Mellitus Patients?

We have previously identified 30 differentially expressed genes when comparing recently diagnosed type 1 diabetes mellitus (DM-1) patients and controls paired for sex, age, and ethnic background. In this article we performed the hierarchical clustering of these genes taking into account the human-leukocyte-antigen (HLA)-DRB1/DQB1 profile. The dendrogram obtained using the Cluster program grouped patients and controls into three clusters, one including individuals with no susceptibility alleles, another including individuals with at least three susceptibility alleles, and a third intermingling susceptibility/protective alleles. In addition to other variables, the results of the present article suggest that the major histocompatibility complex (MHC) class II profile may be of relevance for the study of a large-scale differentially expressed genes.

TNFa-e Microsatellite, HLA-DRB1 and -DQB1 Alleles and Haplotypes in Brazilian Patients Presenting Recently Diagnosed Type 1 Diabetes Mellitus

TNF microsatellite and HLA class II polymorphisms were studied in 28 recently diagnosed Brazilian patients presenting type 1 diabetes mellitus (T1DM) and in 120 healthy controls. TNFa-e and HLA-DRB1/DQB1 alleles were identified using sets of sequence-specific primers. Compared to controls, the DRB1*03 and DQB1*02 allele groups, TNFa1 allele, and the TNFa4-b5-c1-d4-e3 and TNFa10-b5-c1-d4-e3 haplotypes were overrepresented in patients. TNF microsatellite together with HLA polymorphisms is associated with type 1 diabetes in Brazilian patients, corroborating the participation of the MHC genes in disease susceptibility.