Combination of KIR 2DL2 and HLA-C1 (Asn 80) confers susceptibility to type 1 diabetes in Latvians.

Killer immunoglobulin-like receptors (KIRs) are known to modulate natural killer (NK) and NK T-cell function by interacting with human leucocyte antigen (HLA) class I ligands on target cells. The aim of our study was to investigate the influence of KIR2D genes with their HLA-C ligands in susceptibility to type 1 diabetes. A total of 98 type 1 diabetes patients and 70 healthy subjects from Latvia were typed for KIR genes and HLA-C ligands using polymerase chain reaction-based genotyping. The HLA C1+/C2+ combination was positively, and C1-/C2+ combination was negatively, associated with type 1 diabetes. Stratification analysis of KIR/HLA-C ligand combinations showed 2DL2+/C1+, 2DL3+/C1+, and 2DS2+ /C1+ to be positively, and 2DL2-/C1- and 2DS2-/ C1- to be negatively, associated. The presence of 2DL2-HLA-C1 in the absence of 2DS1, 2DS2 confers maximum susceptibility. Absence of 2DL2 and HLA-C1 along with absence of 2DS1 and 2DS2 confer maximum protection. A hypothetical model of KIR/ligand combinations on immune responses and type 1 diabetes susceptibility is proposed. Our results suggest that a combination KIR2DL2- HLA-C1 plays a critical role in susceptibility or protection in Latvians against type 1 diabetes.

Epigenetics and epigenetic mechanisms in disease with emphasis on autoimmune diseases.

Epigenetics deals with molecular heritable patterns relating to chromatin, which exists in two alterable and inter-convertible states. The two conformations of chromatin i.e., compact and relaxed are due to epigenetic regulation. The alterations in chromatin normalize gene expression patterns. Thus, the epigenetic marks on chromatin are the deciding factors for either gene silencing or activation. The epigenetics introduced a new term viz., epiallele which deviates from the classical Mendelian allele. The remodeling of chromatin during embryonic phase, post-translational aberrations of chromatin proteins causing cellular dysfunction and possible epigenetic therapies are discussed in the present article. The role of epigenetic mechanisms in triggering / progression of several autoimmune diseases is being emphasized off late. The study of such complex epigenetic processes becomes very important in understanding the etiopathology of the disease as well as in designing target therapies.

SUMO4 M55V polymorphism affects susceptibility to type I diabetes in HLA DR3- and DR4-positive Swedish patients.

SUMO4 M55V, located in IDDM5, has been a focus for debate because of its association to type I diabetes (TIDM) in Asians but not in Caucasians. The current study aims to test the significance of M55V association to TIDM in a large cohort of Swedish Caucasians, and to test whether M55V is associated in those carrying human leukocyte antigen (HLA) class II molecules. A total of 673 TIDM patients and 535 age- and sex-matched healthy controls were included in the study. PCR-RFLP was performed to identify the genotype and allele variations. Our data suggest that SUMO4 M55V is not associated with susceptibility to TIDM by itself. When we stratified our patients and controls based on heterozygosity for HLA-DR3/DR4 and SUMO4 genotypes, we found that presence of SUMO4 GG increased further the relative risk conferred by HLA-DR3/DR4 to TIDM, whereas SUMO4 AA decreased the risk. From the current study, we conclude that SUMO4 M55V is associated with TIDM in association with high-risk HLA-DR3 and DR4, but not by itself.

No association of SUMO4 M55V with autoimmune diabetes in Asian-Indian patients.

Autoimmune diabetes [type 1 diabetes mellitus (T1DM), latent autoimmune diabetes in adults (LADA) and part of malnutrition-related diabetes] has been shown to have genetic predisposition. Studies in IDDM 5 have lead to the discovery of a novel polymorphism 163 A-->G, of SUMO4 (small ubiquitin-related modifier) gene, associated with risk to T1DM in Asians, but not in Caucasians. We studied patients with T1DM (n = 134), patients with LADA (n = 101), patients with malnutrition-modulated diabetes mellitus (n = 66) and patients with fibrocalculous pancreatic diabetes (n = 43) and healthy controls subjects (n = 114) from Cuttack, India. Polymerase chain reaction-sequence-specific primer (PCR-SSP) was used to amplify the 163 A-->G sequences. Restriction fragment length polymorphism (RFLP) was performed using restriction enzyme Taq I (PCR-RFLP). Differences in the allelic frequencies of the A and the G alleles were tested statistically using Fisher's exact test or chi-squared test wherever appropriate. P-values were considered significant when equal to or less than 0.05. No significant association was detected between SUMO4 M55V and T1DM susceptibility in Asian-Indians. Comparison of the A and G alleles with HLA DR3-DR4 did not result in any significant P-values. No significant association was found between SUMO4 M55V and LADA or malnutrition-related diabetes mellitus (MRDM). Our results show that Asian-Indians with T1DM are different from other Asian populations. Asian-Indians show more similarity to Caucasians with respect to the association of SUMO4 M55V variant in T1DM. Association studies on Asian-Indian patients with LADA and MRDM showed no significant difference in the presence of the A and the G alleles when compared to healthy controls.