Genetic polymorphisms associated with type 2 diabetes in the Arab world: A systematic review and meta-analysis

The associations of IGF2, IGF2R and IGF2BP2 gene polymorphisms with gestational diabetes mellitus: A case-control study

OBJECTIVE

To investigate the associations of Insulin-like growth factor-II (IGF2) gene, Insulin-like growth factor-II receptor (IGF2R) gene and Insulin-like growth factor-II binding protein 2 (IGF2BP2) gene polymorphisms with the susceptibility to gestational diabetes mellitus (GDM) in Chinese population.

METHODS

A total of 1703 pregnant women (835 GDM and 868 Non-GDM) were recruited in this case-control study. All participants underwent prenatal 75 g oral glucose tolerance test (OGTT) examinations during 24-28 gestational weeks at the Maternal and Child Health Hospital of Hubei Province from January 15, 2018 to March 31, 2019. Genotyping of candidate SNPs (IGF2 rs680, IGF2R rs416572, IGF2BP2 rs4402960, rs1470579, rs1374910, rs11705701, rs6777038, rs16860234, rs7651090) was performed on Sequenom MassARRAY platform. Logistic regression analysis was conducted to investigate the associations between candidate SNPs and risk of GDM. In addition, multifactor dimensionality reduction (MDR) method was applied to explore the effects of gene-gene interactions on GDM risk.

RESULTS

There were significant distribution differences between GDM group and non-GDM group in age, pre-pregnancy BMI, education level and family history of diabetes (P < 0.05). After adjusted for age, pre-pregnancy BMI, education level and family history of diabetes, there were no significant associations of the candidate SNPs polymorphisms and GDM risk (P > 0.05). Furthermore, there were no gene-gene interactions on the GDM risk among the candidate SNPs (P > 0.05). However, the fasting blood glucose (FBG) levels of rs6777038 CT carriers were significantly lower than TT carriers (4.69±0.69 vs. 5.03±1.57 mmol/L, P < 0.01), and the OGTT-2h levels of rs6777038 CC and CT genotype carriers were significantly lower than TT genotype carriers (8.10±1.91 and 8.08±1.87 vs. 8.99±2.90 mmol/L, P < 0.01).

CONCLUSIONS

IGF2 rs680, IGF2R rs416572, IGF2BP2 rs4402960, rs1470579, rs11705701, rs6777038, rs16860234, rs7651090 polymorphisms were not significantly associated with GDM risk in Wuhan, China. Further lager multicenter researches are needed to confirm these results.

Meta-analysis of MTHFR C677T polymorphism and type 2 diabetes mellitus in MENA region

BACKGROUND AND AIMS

The association of the C677T polymorphism of the Methylenetetrahydrofolate Reductase (MTHFR) gene with susceptibility to type 2 diabetes mellitus (T2DM) has been widely debated. Therefore, our aim is to conclusively resolve this controversy in the Middle East and North Africa region population through a meta-analysis.

MATERIEL AND METHODS

We identified relevant articles by searching literature databases, such as PubMed, Web of Science, and Science Direct, to retrieve studies that examined the association between the MTHFR C677T polymorphism and the risk of developing T2DM. Using meta-analysis, we calculated the odds ratio (OR) and confidence interval (CI) values of these studies to assess the susceptibility to T2DM related to the C677T polymorphism of MTHFR gene.

RESULTS

In this meta-analysis, we included a total of 13 publications comprising 2072 T2DM patients and 2164 control subjects. The results of the meta-analysis suggested that there is a significant association between the C677T polymorphism and T2DM risk in overall comparisons for allele contrasts (T vs C): OR = 1.25, 95% CI = 1.04-1.50, p = 0.015 and homozygous (TT vs CC): OR = 1.44, 95% CI = 1.01-2.05, p = 0.038). Subgroup analysis revealed that the C677T polymorphism is associated with a risk of T2DM in Asian populations, while there is no significant association between this polymorphism and T2DM in Caucasian and African populations. Furthermore, there was no evidence of publication bias.

CONCLUSION

Our study's results suggest that the allele contrast of the C677T polymorphism of the MTHFR gene is associated with an increased risk of T2DM in the overall population, particularly among Asians.

TCF7L2 and FTO Polymorphisms Are Associated with Type 2 Diabetes Mellitus Risk in Kuwait

OBJECTIVE

Despite the high prevalence of type 2 diabetes mellitus (T2DM) and obesity in the region, reports are limited on genetic risk factors associated with T2DM risk in Kuwait. Our aim was to investigate the association of reported FTO and TCF7L2 T2DM genetic risk variants in Kuwaiti T2DM patients.

SUBJECTS AND METHODS

FTO rs9939609 and TCF7L2 rs7903146 variants were genotyped in 203 T2DM patients and 162 healthy controls. Data analysis included Fisher's exact test, χ2 test, and linear and logistic regression analyses.

RESULTS

FTO rs9939609 (AA) and TCF7L2 rs7903146 (TT) genotypes associated with T2DM risk among Kuwaitis (p = 0.0016 and p < 0.0001; respectively). Both variants had the strongest association with T2DM risk in an autosomal recessive inheritance model (FTO rs9939609A: odds ratio (OR) 2.136, 95% confidence interval (CI): 1.21-3.67, p = 0.0075; TCF7L2 rs7903146T: OR 3.283, 95% CI: 1.92-5.76, p < 0.0001). Moreover, rs7903146T associated with risk of peripheral neuropathy (β = 0.735, 95% CI: 0.514-0.96, p < 0.001) and risk of myocardial infarction (β = 0.36, 95% CI: 0.024-0.7, p = 0.036) in T2DM patients.

CONCLUSION

The increased susceptibility of Kuwaitis to T2DM is influenced by the same common genetic factors found in other T2DM populations. Further investigations of other T2DM genetic risk factors in Kuwait should refine and further support the clinical utility of a genetic risk score in predicting T2DM risk in a high-risk population such as Kuwait.

Genetic and Functional Effects of Adiponectin in Type 2 Diabetes Mellitus Development

Diabetes mellitus (DM) is a common chronic metabolic disease, and the C57BLKsJ-db/db mice are good animal models for type 2 diabetes mellitus (T2DM). In this study, Western blotting and immunohistochemistry (IHC) were employed to examine the protein expression of adiponectin in the liver tissues of T2DM mice with different disease courses (4, 16, and 32 weeks). Adiponectin expression reduced in the liver tissues of T2DM mice in different disease courses. The genotypic and allelic frequencies of the adiponectin gene rs1063538 and rs2241766 single nucleotide polymorphisms (SNPs) in a Taiwanese population (570 T2DM patients and 1700 controls) were investigated. Based on the genetic distribution of the rs2241766 locus, the distribution frequency of the T allele in the T2DM group (72.8%) was higher than in the control group (68.8%). Individuals carrying the G allele had a 0.82-fold greater risk of developing T2DM than individuals carrying the T allele. Differences were evident in the genotypic and allelic distributions (p < 0.05). Enzyme-linked immunosorbent assay (ELISA) was used to measure changes in serum adiponectin protein concentrations in the healthy population and in patients with T2DM. Serum adiponectin concentration in patients with T2DM was lower than in the control group. In summary, adiponectin was determined to be a T2DM susceptibility gene and may be involved in T2DM progression.

The spectrum of chromosomal translocations in the Arab world: ethnic-specific chromosomal translocations and their relevance to diseases

Chromosomal translocations (CTs) are the most common type of structural chromosomal abnormalities in humans. CTs have been reported in several studies in the Arab world, but the frequency and spectrum of these translocations are not well characterized. The aim of this study is to conduct a systematic review to estimate the frequency and spectrum of CTs in the 22 Arab countries. Four literature databases were searched: PubMed, Science Direct, Scopus, and Web of Science, from the time of inception until July 2021. A combination of broad search terms was used to collect all possible CTs reported in the Arab world. In addition to the literature databases, all captured CTs were searched in three chromosomal rearrangement databases (Mitelman Database, CytoD 1.0 Database, and the Atlas of Genetics and Cytogenetics in Oncology and Hematology), along with PubMed and Google Scholar, to check whether the CTs are unique to the Arabs or shared between Arabs and non-Arabs. A total of 9,053 titles and abstracts were screened, of which 168 studies met our inclusion criteria, and 378 CTs were identified in 15 Arab countries, of which 57 CTs were unique to Arab patients. Approximately 89% of the identified CTs involved autosomal chromosomes. Three CTs, t(9;22), t(13;14), and t(14;18), showed the highest frequency, which were associated with hematological malignancies, recurrent pregnancy loss, and follicular lymphoma, respectively. Complex CTs were commonly reported among Arabs, with a total of 44 CTs, of which 12 were unique to Arabs. This is the first study to focus on the spectrum of CTs in the Arab world and compressively map the ethnic-specific CTs relevant to cancer. It seems that there is a distinctive genotype of Arabs with CTs, of which some manifested with unique clinical phenotypes. Although ethnic-specific CTs are highly relevant to disease mechanism, they are understudied and need to be thoroughly addressed.

A Meta-analysis of ADIPOQ rs2241766 polymorphism association with type 2 diabetes

Objective

There is extensive research on the association between polymorphisms in the adiponectin gene (ADIPOQ) and type 2 diabetes (T2D). The present meta-analytic study explored the association between ADIPOQ rs2241766 polymorphisms and T2D.

Metolds

Articles were collected by searching Google Scholar, Scopus, and PubMed electronic databases until 2021. They were searched using a systematic search of original and sensitive English keywords and their equivalent keywords based on the keywords "type 2 diabetes", "ADIPOQ", and "rs2241766". The article selection criteria were based on the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) flow diagram.

Results

The results revealed that there was no bias in this study. Some studies, such as Joshaghani et al. (odds ratio [OR] = 2.18), Hussain et al. (OR = 2.12), Momin (OR = 4.45), and Amal et al. (OR = 1.84), showed an increasing effect of ADIPOQ rs266729 polymorphism on T2D with 95% CI (P ˂ 0.01), while some have shown no significant association between them.

Conclusion

The results of this meta-analytic study showed the relationship between ADIPOQ and rs2241766. Also, it was found that Rs2241766 polymorphism and allele increase the risk, and rs2241766 increases the risk of developing T2D (OR = 1.29).

Single-nucleotide polymorphisms as important risk factors of diabetes among Middle East population

Diabetes is a chronic metabolic disorder that leads to the dysfunction of various tissues and organs, including eyes, kidneys, and cardiovascular system. According to the World Health Organization, diabetes prevalence is 8.8% globally among whom about 90% of cases are type 2 diabetes. There are not any significant clinical manifestations in the primary stages of diabetes. Therefore, screening can be an efficient way to reduce the diabetic complications. Over the recent decades, the prevalence of diabetes has increased alarmingly among the Middle East population, which has imposed exorbitant costs on the health care system in this region. Given that the genetic changes are among the important risk factors associated with predisposing people to diabetes, we examined the role of single-nucleotide polymorphisms (SNPs) in the pathogenesis of diabetes among Middle East population. In the present review, we assessed the molecular pathology of diabetes in the Middle East population that paves the way for introducing an efficient SNP-based diagnostic panel for diabetes screening among the Middle East population. Since, the Middle East has a population of 370 million people; the current review can be a reliable model for the introduction of SNP-based diagnostic panels in other populations and countries around the world.

Association of CAPN10 haplotype combinations with type 2 diabetes mellitus and metabolic syndrome among Egyptians: pilot study—genotyping of three CAPN10 variants

Background

T2DM is a polygenic, metabolic complex and multifactorial disease. Several genes contribute to risk of type 2 diabetes and metabolic syndrome among different populations.

Results

An relationship between three identified CAPN-10 variants [SNP-43 (rs#3792267), SNP-19 (rs#3842570) and SNP-63 (rs#5030952)] localized on 2q37 and type 2 diabetic patients with and without metabolic syndrome (MS) have been reported in our comparative study (diabetic vs health control individuals). Genotyping of study cohorts was carried out using restriction fragment length polymorphism (RFLP-PCR). Statistical analysis of data reveals that the haplotype combination 111/112 confers a significant risk for type 2 diabetes mellitus (T2DM). Patients with the homozygous haplotype combination of 122/122 are less susceptible to MS when compared to other patients carrying other haplotype combinations. Regarding obesity, a core component in MS, the haplotype combinations 111/121 and 122/122 demonstrate a significant protective role. Furthermore, the haplotype combination 111/111 displays a significant risk for high levels of total cholesterol.

Conclusion

Present findings address that these haplotype combinations 111/112, 111/121 and 122/122 of CAPN-10 SNP-43, -19 and -63 constitute unique DNA biomarker fingerprints toward susceptibility and risk for T2DM and MS among Egyptians when compared to other haplotype combinations reported in other populations of different ethnicity. To enhance the power of human evolution control nowadays, mutations and polymorphisms in target genes associated with human diseases should be well understood.

Knowledge discovery in genetics of diabetes in Iran, a roadmap for future researches

Purpose

The pathogenesis of diabetes is considered polygenic as a result of complex interactions between genetic/epigenetic and environmental factors. This review intended to evaluate the scientometric and knowledge gap of diabetes genetics researches conducted in Iran as a case of developing countries, and drawn up a roadmap for future studies.

Methods

We searched Scopus and PubMed databases from January 2015 until December 2019 using the keywords: (diabetes OR diabetic) AND (Iran). All publications were reviewed by two experts and after choosing relevant articles, they were categorized based on the subject, level of evidence, study design, publication year, and type of genetic studies.

Results

Of 10,540 records, 428 articles were met the inclusion criteria. Generally, the number of researches about diabetes genetics rose since 2015. Case-control/cross-sectional and animal studies were the common types of study design and based on the subject, the most frequent researches were about genetic factors involved in diabetes development (38%). Briefly, the top seven genes that were evaluated for T2DM were TCF7L2, APOAII, FTO, PON1, ADIPOQ, MTHFR, and PPARG respectively, and also, CTL4 for T1DM. miR-21, miR-155, and miR-375 respectively were the most micro-RNAs that were evaluated. Furthermore, there were six studies about lncRNAs.

Discussion and Conclusion

Investigation about the genetic of diabetes is progressed although there are some limitations like non-homogenous data from Iran, heterogeneity of ethnicity, and rationale of studies. Compared to the previous analysis in Iran, still, GWAS and large-scale studies are required to achieve better policies for manage and control of diabetes disease.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40200-021-00838-8.

Epidemiology of type 2 diabetes in the Middle East and North Africa: Challenges and call for action

Type 2 diabetes continues to be a serious and highly prevalent public health problem worldwide. In 2019, the highest prevalence of diabetes in the world at 12.2%, with its associated morbidity and mortality, was found in the Middle East and North Africa region. In addition to a genetic predisposition in its population, evidence suggests that obesity, physical inactivity, urbanization, and poor nutritional habits have contributed to the high prevalence of diabetes and prediabetes in the region. These risk factors have also led to an earlier onset of type 2 diabetes among children and adolescents, negatively affecting the productive years of the youth and their quality of life. Furthermore, efforts to control the rising prevalence of diabetes and its complications have been challenged and complicated by the political instability and armed conflict in some countries of the region and the recent coronavirus disease 2019. Broad strategies, coupled with targeted interventions at the regional, national, and community levels are needed to address and curb the spread of this public health crisis.

Genetic Variants Associated With Alzheimer Disease in the 22 Arab Countries: A Systematic Review

BACKGROUND AND AIMS

Alzheimer disease (AD) is a progressive and complex neurodegenerative disease. Approximately 70% of AD risk is attributed to genetic risk factors, including variants in amyloid precursor protein (APP), presenilin 1 (PSEN1), and presenilin 2 (PSEN2) genes. Several studies have revealed a considerable number of candidate loci and genes for AD among different ethnic populations. However, the outcomes of these studies have been inconsistent. In this study, we aimed to investigate the spectrum of variants that are associated with the onset and development of AD among 22 Arab countries.

METHODOLOGY

We systematically searched 4 literature databases (Science Direct, Scopus, PubMed, and Web of Science) from the date of inception until July 2020 using various search terms to obtain all the reported genetic data on Arab AD cases.

RESULTS

In total, 18 studies were included, comprising a total of 2173 individuals, of whom 888 were clinically diagnosed AD patients and were genetically tested for genes and variants associated with AD. A total of 27 variants in 8 genes were found to be associated with AD. Of these variants, 17 were unique to the Arab population and 10 were shared with other ethnic groups.

CONCLUSIONS

There is a dearth of studies on the genetics of AD in the Arab world. There seems to be distinctive genetic and clinical susceptibility profiles for Arab patients with AD.

Genetic polymorphisms associated with obesity in the Arab world: a systematic review

BACKGROUND

Obesity, one of the most common chronic health conditions worldwide, is a multifactorial disease caused by complex genetic and environmental interactions. Several association studies have revealed a considerable number of candidate loci for obesity; however, the genotype-phenotype correlations remain unclear. To date, no comprehensive systematic review has been conducted to investigate the genetic risk factors for obesity among Arabs.

OBJECTIVES

This study aimed to systematically review the genetic polymorphisms that are significantly associated with obesity in Arabs.

METHODS

We searched four literature databases (PubMed, Science Direct, Scopus, and Google Scholar) from inception until May 2020 to obtain all reported genetic data related to obesity in Arab populations. Quality assessment and data extraction were performed individually by three investigators.

RESULTS

In total, 59 studies comprising a total of 15,488 cases and 9,760 controls were included in the systematic review. A total of 76 variants located within or near 49 genes were reported to be significantly associated with obesity. Among the 76 variants, two were described as unique to Arabs, as they have not been previously reported in other populations, and 19 were reported to be distinctively associated with obesity in Arabs but not in non-Arab populations.

CONCLUSIONS

There appears to be a unique genetic and clinical susceptibility profile of obesity in Arab patients.

Association of TCF7L2 rs7903146 Polymorphism with the Risk of Type 2 Diabetes Mellitus (T2DM) Among Kurdish Population in Erbil Province, Iraq

The genetic predispositions responsible for developing type 2 diabetes mellitus (T₂DM) in the Middle East are poorly understood. The rs7903146 single nucleotide polymorphism (SNP) located in transcription factor 7-like-2 (TCF7L2) gene has been recognized to have a vital role in the development of T₂DM disorder. The current study is the first to have researched the possible association between TCF7L2 rs7903146 SNP and T₂DM among Kurdish population in Kurdistan region of Iraq. The study included 212 participants, half of them were T₂DM patients, and the other half were disease-free and normoglycemic controls. Genotyping was performed by using a high throughput cost and time effective tetra-primer amplification refractory mutation system-polymerase chain reaction (Tetra ARMS-PCR) assay. The rs7903146 genotypic frequencies for CC, CT and TT were 24.5%, 69.8%, and 5.7% in T₂DM group respectively, and for the controls were 45.3%, 50.9%, and 3.8% respectively. The frequency of CT genotype was found significantly higher in the cases when compared to the controls (OR = 2.53, 95% CI 1.40-4.57, P value < 0.0019), which indicated that the genotype CT showed risk with diabetes. The T allele showed a high significant frequency in the patients compared to the controls (OR = 1.65, 95% CI 1.10-2.47, P value = 0.014). Our findings demonstrated that the T allele could be a risk factor for increasing the susceptibility of T₂DM incidence among the Iraqi Kurdish population.