Maternal Effect and Familial Aggregation in a Type 2 Diabetic Moroccan Population

Kinship analysis of type 2 diabetes mellitus familial aggregation in Taiwan

BACKGROUND

Family disease history plays a vital role in type 2 diabetes mellitus (T2DM) risk. However, the familial aggregation of T2DM among different kinship relatives warrants further investigation.

METHODS

This nationwide kinship relationship study collected 2000-2016 data of two to five generations of the Taiwanese population from the National Health Insurance Research Database. Approximately 4 million family trees were constructed from the records of 20, 890, 264 Taiwanese residents during the study period. T2DM was diagnosed on the basis of ICD-9-CM codes 250.x0 or 250.x2, with three consecutive related prescriptions. The Cox proportional hazard model was used for statistical analysis.

RESULTS

Compared with their counterparts, individuals who had first-degree relatives with T2DM were more likely to develop T2DM during the follow-up period (hazard ratio [HR], 2.37-27.75), followed by individuals who had second-degree relatives with T2DM (HR, 1.29-1.88). T2DM relative risk was higher in those with an affected mother than in those with affected father. The HR for T2DM was 20.32 (95%CI = 15.64-26.42) among male individuals with an affected twin brother, whereas among female individuals with an affected twin sister, it was 60.07 (95%CI = 40.83-88.36). The HRs presented a dose-response relationship with the number of affected family members.

CONCLUSION

The study suggests a significant familial aggregation of T2DM occurrence; these findings could aid in identifying the high-risk group for T2DM and designing early intervention strategies and treatment plans.

Generalizability of GWA-Identified Genetic Risk Variants for Metabolic Traits to Populations from the Arabian Peninsula

The Arabian Peninsula, located at the nexus of Africa, Europe, and Asia, was implicated in early human migration. The Arab population is characterized by consanguinity and endogamy leading to inbreeding. Global genome-wide association (GWA) studies on metabolic traits under-represent the Arab population. Replicability of GWA-identified association signals in the Arab population has not been satisfactorily explored. It is important to assess how well GWA-identified findings generalize if their clinical interpretations are to benefit the target population. Our recent study from Kuwait, which performed genome-wide imputation and meta-analysis, observed 304 (from 151 genes) of the 4746 GWA-identified metabolic risk variants replicable in the Arab population. A recent large GWA study from Qatar found replication of 30 GWA-identified lipid risk variants. These complementing studies from the Peninsula increase the confidence in generalizing metabolic risk loci to the Arab population. However, both the studies reported a low extent of transferability. In this review, we examine the observed low transferability in the context of differences in environment, genetic correlations (allele frequencies, linkage disequilibrium, effect sizes, and heritability), and phenotype variance. We emphasize the need for large-scale GWA studies on deeply phenotyped cohorts of at least 20,000 Arab individuals. The review further presents GWA-identified metabolic risk variants generalizable to the Arab population.

Heritability and Genetics of Type 2 Diabetes Mellitus in Sub-Saharan Africa: A Systematic Review and Meta-Analysis

OBJECTIVES

Sub-Saharan Africa (SSA) is observing an accelerating prevalence rate of type 2 diabetes mellitus (T2DM) influenced by gene-environment interaction of modifiable and nonmodifiable factors. We conducted a systematic review and meta-analysis on the heritability and genetic risk of T2DM in SSA.

METHODS

We reviewed all published articles on T2DM in SSA between January 2000 and December 2019 and available in PubMed, Scopus, and Web of Science. Studies that reported on the genetics and/or heritability of T2DM or indicators of glycaemia were included. Data extracted included the study design, records of family history, pattern and characteristics of inheritance, genetic determinants, and effects estimates.

RESULTS

The pattern and characteristics of T2DM heritability in SSA are preference for maternal aggregation, higher among first degree compared to second-degree relatives; early age-onset (<50 years), and inherited abnormalities of beta-cell function/mass. The overall prevalence of T2DM was 28.2% for the population with a positive family history (PFH) and 11.2% for the population with negative family history (NFH). The pooled odds ratio of the impact of PFH on T2DM was 3.29 (95% CI: 2.40-4.52). Overall, 28 polymorphisms in 17 genes have been investigated in relation with T2DM in SSA. Almost all studies used the candidate gene approach with most (45.8%) of genetic studies published between 2011 and 2015. Polymorphisms in ABCC8, Haptoglobin, KCNJ11, ACDC, ENPP1, TNF-α, and TCF7L2 were found to be associated with T2DM, with overlapping effect on specific cardiometabolic traits. Genome-wide studies identified ancestry-specific signals (AGMO-rs73284431, VT11A-rs17746147, and ZRANB3) and TCF7L2-rs7903146 as the only transferable genetic risk variants to SSA population. TCF7L2-rs7903146 polymorphism was investigated in multiple studies with consistent effects and low-moderate statistical heterogeneity. Effect sizes were modestly strong [odds ratio = 6.17 (95% CI: 2.03-18.81), codominant model; 2.27 (95% CI: 1.50-3.44), additive model; 1.75 (95% CI: 1.18-2.59), recessive model]. Current evidence on the heritability and genetic markers of T2DM in SSA populations is limited and largely insufficient to reliably inform the genetic architecture of T2DM across SSA regions.

Distribution of glycated haemoglobin and its determinants in Indian young adults

AIM

The aim of the present study is to understand the distribution of A1c in four different age groups in young adults and its relation to other co-variants.

METHODS

The countrywide data was collected in 2017 in Individuals with high risk analysed by Indian Diabetes Risk Score (IDRS) and self-declared diabetics were identified after screening a sample of 240,968 individuals from rural (4 villages of about 500 adults each) and urban (4 census enumeration blocks of about 500 adults each) population spanning 65 districts of 29 states/UTs of Indian subcontinent. Blood tests and other detailed assessments were carried out on this selected group. This study presents the analysis of the A1c values of 2862 young adults (<35 years).

RESULTS

In the age group of 31-34 years, the proportion of Diabetes (22.36%) and Prediabetes (9.86%) was higher in comparison with younger age groups. Also, Diabetes (7.3%) and Prediabetes (22%) were highest among those who had parental history of DM in both parents as compared to those with Diabetes history in one parent [Diabetes (7.1%) or Prediabetes (19.0%)] and no Diabetes Parental History (Diabetes (7.3%) and Prediabetes (18.3%) cases. BMI was found to play a significant positive correlation with Diabetes and Prediabetes (p < 0.001) with range of A1c.

CONCLUSION

Age, BMI and parental history were found to be correlated with A1c levels in IDRS screened high-risk population. With increasing age, the proportion of Diabetics and Prediabetics also increased with positive correlation of age with A1c levels.

Cross-Sectional Survey of Mental Health Risk Factors and Comparison of the Monoamine oxidase A Gene DNA Methylation Level in Different Mental Health Conditions among Oilfield Workers in Xinjiang, China

The incidence of psychological problems among occupational groups is becoming increasingly more serious, and adverse psychological conditions will seriously affect the working ability of occupational groups and harm the health of their bodies. This study adopted a multi-stage stratified cluster sampling method to conduct a cross-sectional survey on the mental health of 3631 oil workers in Karamay, Xinjiang from March 2017 to June 2018. The mental health status of oil workers was evaluated using the Symptom Checklist-90, and mental health risk factors were evaluated. The correlation between the monoamine oxidase A (MAOA) gene and mental health was analyzed, and the DNA methylation level of the MAOA gene was compared between the normal group and the abnormal group. The results show the incidence of mental health problems among oil workers according to differences in age, nationality, type of work, length of service, professional title, shift work, and marital status. The evaluation of mental health risk factors revealed that shift work, occupational stress, and high payment/low return affect mental health. The somatization scores of different genotypes of rs6323 in the MAOA gene were statistically significant (p < 0.05), suggesting that the somatization scores of different genotypes of rs6323 were different. According to the average rank, the TT genotype group had the highest score, followed by the GT genotype group, and the GG genotype group had the lowest score. The level of DNA methylation in the abnormal group was lower than that in the normal group (p < 0.05). The results suggested that occupational mental health can be enhanced by improving shift work, reducing stress, and balancing effort and reward. This preliminary investigation suggests that methylation status can affect mental health, indicating that methylation level may be a predictor of mental health status.

A Perception on Genome-Wide Genetic Analysis of Metabolic Traits in Arab Populations

Despite dedicated nation-wide efforts to raise awareness against the harmful effects of fast-food consumption and sedentary lifestyle, the Arab population continues to struggle with an increased risk for metabolic disorders. Unlike the European population, the Arab population lacks well-established genetic risk determinants for metabolic disorders, and the transferability of established risk loci to this population has not been satisfactorily demonstrated. The most recent findings have identified over 240 genetic risk loci (with ~400 independent association signals) for type 2 diabetes, but thus far only 25 risk loci (ADAMTS9, ALX4, BCL11A, CDKAL1, CDKN2A/B, COL8A1, DUSP9, FTO, GCK, GNPDA2, HMG20A, HNF1A, HNF1B, HNF4A, IGF2BP2, JAZF1, KCNJ11, KCNQ1, MC4R, PPARγ, SLC30A8, TCF7L2, TFAP2B, TP53INP1, and WFS1) have been replicated in Arab populations. To our knowledge, large-scale population- or family-based association studies are non-existent in this region. Recently, we conducted genome-wide association studies on Arab individuals from Kuwait to delineate the genetic determinants for quantitative traits associated with anthropometry, lipid profile, insulin resistance, and blood pressure levels. Although these studies led to the identification of novel recessive variants, they failed to reproduce the established loci. However, they provided insights into the genetic architecture of the population, the applicability of genetic models based on recessive mode of inheritance, the presence of genetic signatures of inbreeding due to the practice of consanguinity, and the pleiotropic effects of rare disorders on complex metabolic disorders. This perspective presents analysis strategies and study designs for identifying genetic risk variants associated with diabetes and related traits in Arab populations.

Effect of Family History of Diabetes on Hemoglobin A1c Levels among Individuals with and without Diabetes: The Dong-gu Study

PURPOSE

We investigated associations between family history of diabetes (FHD) and hemoglobin A1c (HbA1c) level, among people with and without diabetes.

MATERIALS AND METHODS

In total, 7031 people without diabetes and 1918 people with diabetes who participated in the Dong-gu Study were included. Data on FHD in first-degree relatives (father, mother, and siblings) were obtained. Elevated HbA1c levels in people without diabetes and high HbA1c levels in people with diabetes were defined as the highest quintiles of HbA1c ≥5.9% and ≥7.9%, respectively.

RESULTS

In people without diabetes, the odds of elevated HbA1c levels [odds ratio (OR) 1.34, 95% confidence interval (CI) 1.13-1.59] were significantly greater in people with any FHD than in those without. Specifically, the odds of elevated HbA1c levels in people without diabetes with an FHD involving siblings were greater than in those without an FHD involving siblings. Additionally, in people with diabetes, the odds of high HbA1c levels (OR 1.33, 95% CI 1.02-1.72) were greater in people with any FHD than in those without such history. Moreover, people with diabetes with maternal FHD had increased odds of high HbA1c levels.

CONCLUSION

FHD was associated not only with high HbA1c levels in people with diabetes, but also with elevated HbA1c levels in people without diabetes.

Investigating spousal concordance of diabetes through statistical analysis and data mining

OBJECTIVE

Spousal clustering of diabetes merits attention. Whether old-age vulnerability or a shared family environment determines the concordance of diabetes is also uncertain. This study investigated the spousal concordance of diabetes and compared the risk of diabetes concordance between couples and noncouples by using nationally representative data.

METHODS

A total of 22,572 individuals identified from the 2002-2013 National Health Insurance Research Database of Taiwan constituted 5,643 couples and 5,643 noncouples through 1:1 dual propensity score matching (PSM). Factors associated with concordance in both spouses with diabetes were analyzed at the individual level. The risk of diabetes concordance between couples and noncouples was compared at the couple level. Logistic regression was the main statistical method. Statistical data were analyzed using SAS 9.4. C&RT and Apriori of data mining conducted in IBM SPSS Modeler 13 served as a supplement to statistics.

RESULTS

High odds of the spousal concordance of diabetes were associated with old age, middle levels of urbanization, and high comorbidities (all P < 0.05). The dual PSM analysis revealed that the risk of diabetes concordance was significantly higher in couples (5.19%) than in noncouples (0.09%; OR = 61.743, P < 0.0001).

CONCLUSIONS

A high concordance rate of diabetes in couples may indicate the influences of assortative mating and shared environment. Diabetes in a spouse implicates its risk in the partner. Family-based diabetes care that emphasizes the screening of couples at risk of diabetes by using the identified risk factors is suggested in prospective clinical practice interventions.

Novel variants of mitochondrial DNA associated with Type 2 diabetes mellitus in Moroccan population

In this study, we investigated the association of mtDNA variants and haplogroups with Type 2 diabetes (T2D) in Moroccan patients. The Hypervariable Segments 1 of the mtDNA was sequenced in 108 diabetic patients and 97 controls. Association analyses were performed using Fisher's exact test and multivariate logistic regression. The prevalence of five mtDNA variants (C16187T, C16270T, T16172C, A16293G, and C16320T) was significantly higher in cases than in controls. Among these variants, only C16270T (p = .02) and C16320T (p = .03) remains significant after adjusting by age and gender. We showed that C16270T and C16320T variants were strongly associated with increased risk of T2D in Moroccan patients.

TNF A -308G>A polymorphism in Moroccan patients with type 2 diabetes mellitus: a case-control study and meta-analysis

Type 2 diabetes mellitus (T2DM) is one of causes of mortality and morbidity in Moroccan population. The identification of genes implicated in this disease can help to found a specific treatment and to improve the quality of life for type 2 diabetic patients. In this study we analyze the association between a polymorphism (-308G>A) of TNF A promoter gene and T2DM in Moroccan patients. Five hundred and fifty-one individuals (307 patients with T2DM and 244 controls) were genotyped for this polymorphism by PCR-RFLP. This association was further reconsidered by a meta-analysis on 21 studies including 8,187 cases and 7,811 controls. We found that in Moroccan patients the -308A allele is strongly associated with T2DM (p = 0.000002; odds ratio 1.79, 95 % confidence interval 1.41-2.28). Based on our meta-analysis, there was no significant association detected between the TNF A -308G>A polymorphism and risk for T2DM. Our results suggest that the -308G>A polymorphism is a genetic risk factor for the development of T2DM in Moroccan population. On the other hand the meta analysis results led to controversial conclusions in other ethnicities.

Maternal history of diabetes is associated with increased cardiometabolic risk in Chinese

OBJECTIVE

Positive family history is associated with increased type 2 diabetes (T2D) risk, and reflects both genetic and environmental risks. Several studies have suggested an excess maternal transmission of T2D, although the underlying mechanism is unknown. We aimed to examine the association between maternal diabetes and cardiometabolic risk in the offspring.

METHODS

Parental history of diabetes and clinical data including anthropometric traits, fasting plasma glucose and insulin (FPG, FPI), blood pressure and lipid profile were collected from 2581 unrelated Chinese offspring (2026 adolescents from a population-based school survey and 555 adults from a community-based health screening programme). A subset of subjects (n=834) underwent oral glucose tolerance test to measure the glucose and insulin concentrations at 0, 15, 30, 60 and 120 min for evaluation of the areas under the curve (AUC) of glucose and insulin at 0-120 min, homoeostasis model assessment of insulin resistance (HOMA-IR) and bell-cell function, insulinogenic index, insulin sensitivity index (ISI) and oral disposition index (DI).

RESULTS

A positive parental history of diabetes was associated with increased risk of obesity (odd ratios (OR) (95% confidence interval (CI))=1.48 (1.10-2.00)), central obesity (OR (95% CI)=1.67 (1.21-2.32)), higher FPI, HOMA-IR, 2-h insulin, AUC of glucose at 0-120 min, triglycerides, reduced ISI and DI. Compared with individuals without parental diabetes, offspring with diabetic mother had significantly increased risk of obesity (OR (95% CI)=1.59 (1.07-2.35)), central obesity (OR (95% CI)=1.88 (1.23-2.88)), higher glucose levels and BP, were more insulin resistant but also had impaired first-phase insulin response and worse lipid profile. However, paternal history of diabetes had no effect on any of the studied traits, except higher body mass index, waist circumference in females and FPG.

CONCLUSIONS

Our findings suggested that maternal history of diabetes conferred increased risk of cardiometabolic abnormalities, and was associated with both insulin resistance and impaired first-phase insulin secretion. Further investigation into the mechanism of transgenerational diabetes is warranted.

Familial Clustering of Type 2 Diabetes among Omanis

OBJECTIVE

The aim of this study was to screen Omani individuals for the familial aggregation of type 2 diabetes mellitus.

METHODS

A random cohort of 1182 Omani individuals visiting the Family Medicine Clinic at Sultan Qaboos University Hospital (SQUH), Muscat, Oman, for regular medical checkup, aged ≥40 years, were sampled. Patients were categorized into three groups: (1) individuals who claim not to have diabetes and had no family history of diabetes; (2) individuals who claim not to have diabetes but had family history of diabetes; (3) individuals with diabetes. Only 16% of these Omani individuals had no diabetes and no family history of diabetes. Another separate random cohort of 234 Omani type 2 diabetes mellitus patients, from the Diabetes Clinic at SQUH, were interviewed and questioned about their family history of type 2 diabetes mellitus.

RESULTS

Ninety five percent of the patients had a family history of diabetes. Eighty percent had first degree relatives with diabetes and 46% had second degree relatives with diabetes. At least one parent with diabetes was reported among 55% of these diabetics, while maternal diabetes (55%) was found to be higher than paternal diabetes (47%). However, only 15% had both parents with diabetes. Furthermore, almost half of the 234 diabetics were having at least one of the following relatives with diabetes: brother, sister, aunt or an uncle.

CONCLUSION

The findings of this study confirm familial aggregation of diabetes among the Omani population. Compared to other populations, familial aggregation of type 2 diabetes mellitus among Omanis is relatively very high, and is perhaps due to the very high degree of consanguinity among Omanis. Since almost everyone seems to have a genetic predisposition to diabetes, the dramatic lifestyle changes over the past 25 years, could tip the population into an epidemic of type 2 diabetes mellitus.

Association study of mitochondrial DNA polymorphisms with type 2 diabetes in Tunisian population

Mitochondrial DNA (mtDNA) variation may play an important role in the pathogenesis of type 2 diabetes (T2Ds). In this study, we aimed to explore whether mtDNA variants contribute to the susceptibility to T2Ds in a Tunisian population. The hypervariable region 1 (HVS1) of the mtDNA of 64 T2Ds patients and 77 healthy controls was amplified and sequenced. Statistical analysis was performed using the STATA program. Analysis of the total screened variants (N = 88) from the HVS1 region showed no significant difference in the distribution of all polymorphisms between T2Ds and controls, except for the variant G16390A which was more frequent in T2Ds (15.9%) than in controls (5.4%) (p = 0.04). The association of G16390A was not detected after multivariate regression analysis. Similarly, analysis of the distribution of mitochondrial haplogroups within our dataset showed 18 distinct major haplogroups with no significant difference between T2Ds and controls. Except, the weakly association found for the G16390A variant, our results showed that none of the tested polymorphisms from the HVS1 region have a major role in T2Ds pathogenesis in the studied Tunisian population even when taking into account the population stratification.

Type 2 diabetes in Mauritania: prevalence of the undiagnosed diabetes, influence of family history and maternal effect

AIM

We estimated the prevalence of undiagnosed diabetes, analyzed the influence of family history on the occurrence of T2D and evaluated its aggregation pattern in the Mauritanian population.

METHODS

The prevalence of unknown diabetes was obtained using data compiled from 1278 Mauritanian adults applying a questionnaire and fasting serum glucose tests. Detailed family history of diabetes and clinical characteristics were gathered from 421 T2D patients.

RESULTS

The prevalence of undiagnosed diabetes was 4.7 ± 1.2% in the studied population (3.1% in men and 6.4% in women). 27% of T2D patients reported at least one relative with diabetes. Association between family history and diabetes was higher among first degree compared to second degree relatives (p=0.003). We observed more probands with an affected mother than those who have a father with diabetes (p = 0.002), suggesting a preferential maternal effect which did not extend to second degree relatives.

CONCLUSIONS

These results show that the prevalence of diabetes in the Mauritanian population could be higher than currently thought. Family history screening may be used in the management of this condition in Mauritania.

Association of the C677T polymorphism in the human methylenetetrahydrofolate reductase (MTHFR) gene with the genetic predisposition for type 2 diabetes mellitus in a Moroccan population

AIMS

Type 2 diabetes mellitus (T2DM) is a major public health problem around the world. The C677T and A1298C polymorphisms of the methylenetetrahydrofolate reductase (MTHFR) gene have been reported to be associated with T2DM and its complications. This study aimed to investigate this association in the Moroccan population.

METHODS

A case-control study was performed among 282 Moroccan diabetic patients and 232 healthy controls. The MTHFR C677T and A1298C polymorphisms were genotyped by polymerase chain reaction, followed by enzymatic digestion with HinfI and MboII enzymes, respectively.

RESULTS

There was a significant association between C677T polymorphism and T2DM in both additive and dominant models. In addition, the 677T allele frequency differed significantly between the diabetic and control groups (26.06% vs. 33.20%, respectively). However, no significant association was found between A1298C polymorphism and T2DM. The frequencies of combined genotypes 677CC/1298AA and 677CT/1298AC differed significantly between the diabetic and control groups (32.62% vs. 20.61% and 9.57% vs. 17.55%, respectively).

CONCLUSIONS

These results show an evident association between the MTHFR C677T polymorphism and T2DM in Moroccan patients but no significant association with the MTHFR A1298C polymorphism.