Background: Mitochondrial dysfunction is implicated in the pathogenesis of type 2 diabetes (T2D) via impaired glucose-stimulated insulin secretion in pancreatic beta cells and decreased oxidative phosphorylation in insulin target tissues. Several global studies have been performed to delineate the genetic associations of mitochondrial DNA (mtDNA) haplogroups and variants with T2D incidence. Maternal haplogroups F, D, M9 and N9a and a rare variant (mtDNA 3243 A>G) and a common variant (mtDNA 16189 T>C) were associated with increased risk of T2D in different populations. It is worth noting that some of these proposed associations were not consistent across populations. Since the Gulf Cooperation Council (GCC) countries are marked by high prevalence of T2D, we aim to study association of mitochondrial haplogroups and variants in Arabs from GCC region. Methods: We examined mitochondrial haplogroups and variants in 1,112 Kuwaiti and Qatari native individuals using whole exome sequencing data. The cohort was divided into T2D cases (685) and non-T2D controls (427). Results: The association tests indicated that individuals with haplogroup H have a protective effect against T2D with a suggestive significance [odds ratio (OR) = 0.65; P = 0.022]. The haplogroup H association remained significant even after adjusting for age, sex, and body mass index (BMI) (OR= 0.607; P= 0.021). We also identified mtDNA variants with suggestive significance of association (adjusting for covariates) with T2D. Conclusion: The study demonstrates that maternal H haplogroup, which we previously identified as protective towards obesity in Kuwaiti Arabs, is a protective haplogroup for T2D in Arabs from GCC. Further, the mtDNA variants delineated as associated with T2D are from genes involved in cell energy production. Disclosure M.H.Dashti: None. N.Ali: None. H.Alsaleh: None. R.Nizam: None. F.Almulla: None. A.T.Thangavel: None.

We Have previously established that caveolin-1 (CAV1) rs1997623 C/A variant is associated with metabolic syndrome in obese children (PMID: 30622557) and adults (ADA 82) . Here, we evaluated the functional role of the identified variant in association with obesity. Sequence analysis revealed that the variant is located at CAV1 regulatory region and creates a site for EBF Transcription Factor 1 (EBF1) . DNA fragment (240pb) flanking the variant was cloned upstream luciferase reporter gene. Wildtype, CAV1-C-Luc, and the generated mutant, CAV1-A-Luc, were individually transfected into pre-adipocytes. CAV1-A-luc significantly upregulated Luciferase activity indicating a prospective functional role of CAV1-A allele in CAV1 regulation. The reporter gene activity was differential regulated in lean versus obese pre-adipocytes. Co-transfections with EBF1 construct resulted in a significant upregulation in CAV1-A Luc activity, particularly in pre-adipocytes from obese individuals. The role of EBF1 was further evaluated in vivo using ChIP assays. PCR analysis using specific primers flanking the CAV1 variant and anti-bodies against EBF1 showed a significant elevated enrichment of chromatins from obese individuals, which was also associated with an enrichment for H3K27ac at the same locus, indicating active transcription. Moreover, CAV1 expression was differentially regulated in response to EBF1 siRNA/overexpression in pre-adipocytes harboring CAV1 A/A or A/C alleles relative to that with C/C allele. Furthermore, a significant reduction of DNA methylation at the variant locus was observed particularly in preadipocytes with A/A alleles. Finally, RNA isolated from adipose tissue of lean and obese individuals showed a significant correlation between CAV1 and cytokines transcripts in healthy obese individuals, at least in part, is due to CAV1 rs1997623 variant as verified by sequence analysis. Taken together, our study delineates the role of CAV1 rs1997623 variant in the context of obesity and MetS. Disclosure A.Al madhoun: None. D.Haddad: None. S.P.Kochumon: None. R.Nizam: None. S.Jacob: None. S.T.Sindhu: None. R.Ahmad: None. F.Almulla: None. Funding Kuwait Foundation for the Advancement of Sciences (KFAS) and Dasman Diabetes Institute, Project RA CB-2021-007

Studies have implicated CAV1 in the pathophysiology of diabetes and obesity. Previously, we demonstrated a potential association between the CAV1 rs1997623 C/A variant and metabolic syndrome (MetS) in Kuwaiti children. In the present study, we substantiate the association of CAV1 with MetS in adult Arab individuals. Method: The CAV1 rs1997623 was genotyped in three cohorts of Arabs (n=479) , South Asians (n=660) and South East Asians (n=362) . MetS status of the individuals was diagnosed using the IDF criteria (i.e., presence of central obesity and of at least two abnormalities of high TG, low HDL, hypertension, or type 2 diabetes) . The quantitative measure of MetS was calculated as siMS=2*WC/Height + FBG/5.6 + TG/1.7 + SBP/130 - HDL/1.02 for males or HDL/1.28 for females. Allelic associations with quantitative and dichotomous traits were assessed using linear and logistic regression, respectively, with and adjustment for age and sex. CAV1 transcripts were quantified in adipose tissues from a cohort of 50 Arab individuals differing in siMS score. Results: The CAV1 variant was significantly associated with MetS status (OR=1.8[1.25-2.61]; P-value=0.0015; Pemp=0.0013) and with siMS (Effect size = 0.206; P-value=0.0035; Pemp=0.0028) in the cohort of Arab individuals. The variant was weakly and insignificantly associated in the cohorts of South Asian and South East Asian individuals (OR= 1.and 1.11; P-values= 0.25 and 0.67, respectively) . siMS scores correlated positively with mRNA levels of CAV1 in adipose tissue. Conclusion: The association of CAV1 rs1997623 C/A with MetS in Arab pediatric is now demonstrated in adults as well. Higher expression levels were seen in individuals poses increasing MetS rates further validates the implication of CAV1 rs1997623 C/A variant in MetS phenotype. Only a weak association signal was seen in the South Asian and South East Asian populations leading us to propose that the CAV1 rs1997623 association with MetS is probably specific to Arab ethnicity. Disclosure A.Al madhoun: None. P.Hebbar: None. R.Nizam: None. D.Haddad: None. M.H.Dashti: None. M.Abu-farha: None. R.Ahmad: None. A.T.Thangavel: None. F.Almulla: None. Funding Kuwait Foundation for the Advancement of Sciences (KFAS) and Dasman Diabetes Institute, Project RA CB-2021-007

There has recently been a growing interest in examining the role of epigenetic modifications, such as DNA methylation, in the etiology of type 1 diabetes (T1D) . This study aimed to delineate differences in methylation patterns between T1D-affected and healthy individuals by examining the genome-wide methylation of individuals from three Arab families from Kuwait with T1D-affected mono-/dizygotic twins and non-twinned siblings. Bisulfite sequencing of DNA from the peripheral blood of affected and healthy individuals from each of the three families was performed. Methylation profiles of the affected individuals were compared to those of healthy individuals. The principal component analysis on methylation profiling based on base-pair resolution clustered the T1D-affected twins together family-wide. Sites/regions that were differentially methylated between T1D and healthy samples harbored 84 genes, of which 18 were known to be differentially methylated in T1D individuals compared to healthy individuals in publicly available gene expression data resources. We further validated two of the 18 genes—namely ICA1 and DRAM1 that were hypermethylated in T1D samples compared to healthy samples—for upregulation in T1D samples from an extended study cohort of familial T1D. The ICA1 is well-known to have a role in the development of autoimmune beta-cell destruction. Disclosure M.H.Dashti: None. R.Nizam: None. P.Hebbar: None. S.Jacob: None. S.E.John: None. A.M.Channanath: None. H.Alkandari: None. A.T.Thangavel: None. F.Almulla: None. Funding Kuwait Foundation for Advancement in Sciences funding RA-2014-024