Uncovering the genetic history of the present-day Greenlandic population

The use of artificial intelligence to assess diabetic eye disease among the Greenlandic population

Background: Retina fundus images conducted in Greenland are telemedically assessed for diabetic retinopathy by ophthalmological nurses in Denmark. Applying an AI grading solution, in a Greenlandic setting, could potentially improve the efficiency and cost-effectiveness of DR screening.Method: We developed an AI model using retina fundus photos, performed on persons registered with diabetes in Greenland and Denmark, using Optos® ultra wide-field scanning laser ophthalmoscope, graded according to ICDR.Using the ResNet50 network we compared the model's ability to distinguish between different images of ICDR severity levels in a confusion matrix.Results: Comparing images with ICDR level 0 to images of ICDR level 4 resulted in an accuracy of 0.9655, AUC of 0.9905, sensitivity and specificity of 96.6%.Comparing ICDR levels 0,1,2 with ICDR levels 3,4, we achieved a performance with an accuracy of 0.8077, an AUC of 0.8728, a sensitivity of 84.6% and a specificity of 78.8%. For the other comparisons, we achieved a modest performance.Conclusion: We developed an AI model using Greenlandic data, to automatically detect DR on Optos retina fundus images. The sensitivity and specificity were too low for our model to be applied directly in a clinical setting, thus optimising the model should be prioritised.

The 1919-21 influenza pandemic in Greenland

In Alaska, the 1918-20 influenza pandemic was devastating, with mortality rates up to 90% of the population, while in other arctic regions in northern Sweden and Norway mortality was considerably lower. We investigated the timing and age-patterns in excess mortality in Greenland during the period 1918-21 and compare these to other epidemics and the 1889-92 pandemic. We accessed the Greenlandic National Archives and transcribed all deaths from 1880 to 1921 by age, geography, and cause of death. We estimated monthly excess mortality and studied the spatial-temporal patterns of the pandemics and compared them to other mortality crises in the 40-year period. The 1918-21 influenza pandemic arrived in Greenland in the summer of 1919, one year delayed due to ship traffic interruptions during the winter months. We found that 5.2% of the Greenland population died of the pandemic with substantial variability between counties (range, 0.1% to 11%). We did not see the typical pandemic age-pattern of high young-adult mortality, possibly due to high baseline mortality in this age-group or remoteness. However, despite substantial mortality, the mortality impact was not standing out relative to other mortality crises, or of similar devastation reported in Alaskan populations.

Inuit population have shorter gastric emptying, higher duodenal motility and altered pan-enteric micromilieu: a comparative study between Greenlandic and Danish populations with and without type 2 diabetes

Gastrointestinal function plays a pivotal role in nutrient absorption and overall digestive health. Abnormal gastric emptying is closely linked to type 2 diabetes, impacting blood glucose regulation and causing gastrointestinal symptoms. This study aims to investigate and compare segmental transit times, motility indices, and micromilieu between Greenlandic Inuit and Danish individuals with and without type 2 diabetes. We included forty-four Greenlandic Inuit, twenty-three of whom had type 2 diabetes, and age and gender-matched Danish individuals. Segmental transit time, motility, and luminal environment were measured using the SmartPill®. Greenlandic controls displayed shorter gastric emptying time (GET) (163 min), higher gastric median pH (2.0 pH) and duodenal median contractions (18.2 mm Hg) compared to Greenlanders with type 2 diabetes (GET: 235 min, pH:1.9, median duodenal contraction 18.4 mm Hg) and Danish controls (GET: 190, pH:1.2 median duodenal contraction 17.5 mmHg). Despite similar anti-diabetic management efforts, variations in gastrointestinal physiology were evident, highlighting the complexity of diabetes and its interaction with ethnicity, suggesting potential dietary or even genetic influences, emphasising the necessity for personalised diabetes management approaches. Finally, the study opens possibilities for future research, encouraging investigations into the underlying mechanisms linking genetics, diet, and gastric physiology, as an understanding of factors can lead to more effective, tailored strategies for diabetes care and improved digestive health in diverse populations.

Ethnic differences in CT derived abdominal body composition measures: a comparative retrospect pilot study between European and Inuit study population

Understanding ethnic variations in body composition is crucial for assessing health risks. Universal models may not suit all ethnicities, and there is limited data on the Inuit population. This study aimed to compare body composition between Inuit and European adults using computed tomography (CT) scans and to investigate the influence of demographics on these measurements. A retrospective analysis was conducted on 50 adults (29 Inuit and 21 European) who underwent standard trauma CT scans. Measurements focused on skeletal muscle index (SMI), various fat indices, and densities at the third lumbar vertebra level, analyzed using the Wilcoxon-Mann-Whitney test and multiple linear regression. Inuit women showed larger fat tissue indices and lower muscle and fat densities than European women. Differences in men were less pronouncehd, with only Intramuscular fat density being lower among Inuit men. Regression indicated that SMI was higher among men, and skeletal muscle density decreased with Inuit ethnicity and age, while visceral fat index was positively associated with age. This study suggests ethnic differences in body composition measures particularly among women, and indicates the need for Inuit-specific body composition models. It higlights the importance of further research into Inuit-specific body composition measurements for better health risk assessment.

Quality of care among patients diagnosed with atrial fibrillation in Greenland

This cross-sectional study sought to assess the prevalence of atrial fibrillation (AF) diagnosis in Greenland among various age groups and examine the corresponding quality of care. We collected data from Greenland's electronic medical records and evaluated the quality of care using six internationally recommended indicators, which are: percentage of AF patients with an assessment of smoking status within the previous year, an assessment of body mass index within the previous year, assessment of blood pressure within the previous year, measurement of thyroid stimulating hormone (TSH), treatment with an anticoagulant and percentage of patients with a measurement of serum-creatinine. We found the prevalence of AF among patients aged 20 years or older in Greenland to be 1.75% (95% CI 1.62-1.88). We found an increasing prevalence of AF with age and a greater proportion of men than women until the age of 74 years. Our study suggests that the associated quality of care could be higher as the requirement of only one of the six quality indicators was met. A lack of registration may partly explain this, and initiatives to improve the quality of care are recommended.

Analysis of admixed Greenlandic siblings shows that the mean genotypic values for metabolic phenotypes differ between Inuit and Europeans

BACKGROUND

Disease prevalence and mean phenotype values differ between many populations, including Inuit and Europeans. Whether these differences are partly explained by genetic differences or solely due to differences in environmental exposures is still unknown, because estimates of the genetic contribution to these means, which we will here refer to as mean genotypic values, are easily confounded, and because studies across genetically diverse populations are lacking.

METHODS

Leveraging the unique genetic properties of the small, admixed and historically isolated Greenlandic population, we estimated the differences in mean genotypic value between Inuit and European genetic ancestry using an admixed sibling design. Analyses were performed across 26 metabolic phenotypes, in 1474 admixed sibling pairs present in a cohort of 5996 Greenlanders.

RESULTS

After FDR correction for multiple testing, we found significantly lower mean genotypic values in Inuit genetic ancestry compared to European genetic ancestry for body weight (effect size per percentage of Inuit genetic ancestry (se), -0.51 (0.16) kg/%), body mass index (-0.20 (0.06) kg/m2/%), fat percentage (-0.38 (0.13) %/%), waist circumference (-0.42 (0.16) cm/%), hip circumference (-0.38 (0.11) cm/%) and fasting serum insulin levels (-1.07 (0.51) pmol/l/%). The direction of the effects was consistent with the observed mean phenotype differences between Inuit and European genetic ancestry. No difference in mean genotypic value was observed for height, markers of glucose homeostasis, or circulating lipid levels.

CONCLUSIONS

We show that mean genotypic values for some metabolic phenotypes differ between two human populations using a method not easily confounded by possible differences in environmental exposures. Our study illustrates the importance of performing genetic studies in diverse populations.

Performance of a 74-Microhaplotype Assay in Kinship Analyses

Microhaplotypes (MHs) consisting of multiple SNPs and indels on short stretches of DNA are new and interesting loci for forensic genetic investigations. In this study, we analysed 74 previously defined MHs in two of the populations that our laboratory provides with forensic genetic services, Danes and Greenlanders. In addition to the 229 SNPs that originally made up the 74 MHs, 66 SNPs and 3 indels were identified in the two populations, and 45 of these variants were included in new definitions of the MHs, whereas 24 SNPs were considered rare and of little value for case work. The average effective number of alleles (Ae) was 3.2, 3.0, and 2.6 in Danes, West Greenlanders, and East Greenlanders, respectively. High levels of linkage disequilibrium were observed in East Greenlanders, which reflects the characteristics of this population that has a small size, and signs of admixture and substructure. Pairwise kinship simulations of full siblings, half-siblings, first cousins, and unrelated individuals were performed using allele frequencies from MHs, STRs and SNPs from Danish and Greenlandic populations. The MH panel outperformed the currently used STR and SNP marker sets and was able to differentiate siblings from unrelated individuals with a 0% false positive rate and a 1.1% false negative rate using an LR threshold of 10,000 in the Danish population. However, the panel was not able to differentiate half-siblings or first cousins from unrelated individuals. The results generated in this study will be used to implement MHs as investigative markers for relationship testing in our laboratory.

Ethnic endotypes in paediatric atopic dermatitis depend on immunotype, lipid composition and microbiota of the skin

BACKGROUND

Atopic dermatitis (AD) endotypes differ with ethnicity. We examined the skin microbiota, cytokine and lipid profiles in Greenlandic Inuit and Danish children with AD.

METHODS

Twenty-five Inuit children with AD and 25 Inuit control children were clinically examined and compared to previously collected data from 25 Danish children with AD. Skin tape strips and skin swabs were collected from lesional and non-lesional skin. Levels of cutaneous immune biomarkers, free sphingoid bases and their (glycosyl)ceramides were analysed. Skin swabs were analysed with 16S rRNA and tuf gene for characterization of bacterial species communities.

RESULTS

Bacterial β-diversity was significantly different between Inuit and Danish AD skin, in both lesional (p < 0.001) and non-lesional (p < 0.001) AD skin, and there was a higher relative abundance of Staphylococcus aureus in Danish compared to Inuit lesional (53% vs. 8%, p < 0.01) and non-lesional skin (55% vs. 5%, p < 0.001). Danish AD children had a higher α-diversity than Inuit children in non-lesional (p < 0.05) but not in lesional skin. Significantly higher levels of type 2 immunity cytokine interleukin (IL)-4 (p < 0.05) and IL-5 (p < 0.01) were identified in Inuit compared to Danish AD children. In contrast, IL-33 (p < 0.01) was higher in Danish lesional and non-lesional AD skin. Higher levels of long-chain glucosylceramide (GlcCER)[S](d26:1) were found in lesional (p < 0.001) and non-lesional (p < 0.001) Inuit skin compared with Danish AD skin. NMF levels were similar in Inuit and Danish AD skin.

CONCLUSION

Skin microbiota, cytokine and lipid composition differed significantly between Inuit and Danish children with AD and showed a stronger type 2 immune signature in Inuit children.

The effect of diabetes and the diabetogenic TBC1D4 p.Arg684ter variant on kidney function in Inuit in Greenland

The aim of this study was to examine the effect of diabetes and the diabetogenic TBC1D4 variant on kidney function in Greenland in a population-based setting. Health survey data and TBC1D4 genotypes from 5,336 Greenlanders were used to estimate odds ratios (ORs) of albuminuria (>30 mg/g creatinine) and chronic kidney disease (CKD, eGFR <60 ml/min/1.73m²), comparing individuals with and without diabetes, including the effect of TBC1D4 variant. Of the 3,909 participants with complete data, 9.3% had diabetes. Albuminuria was found in 27.6% and 9.5% and CKD was found in 10.8% and 6.3% among those with and without diabetes, respectively. Diabetes was cross-sectionally associated with an increased risk of albuminuria (OR (95% CI) = 2.37 (1.69,3.33); p < 0.001) and the TBC1D4 variant protected against albuminuria (OR (95% CI) = 0.44 (0.22,0.90); p = 0.02) in a multivariable model. Neither diabetes nor the TBC1D4 variant significantly associated with CKD. The presence/absence of diabetes did not predict changes in eGFR and UACR in longitudinal analyses. Diabetes conferred an increased risk of albuminuria, and the TBC1D4 variant was associated with a decreased risk of albuminuria, but neither was associated with CKD. The potential renoprotective association of the TBC1D4 variant on albuminuria calls for further studies.

Guidelines for genetic ancestry inference created through roundtable discussions

The use of genetic and genomic technology to infer ancestry is commonplace in a variety of contexts, particularly in biomedical research and for direct-to-consumer genetic testing. In 2013 and 2015, two roundtables engaged a diverse group of stakeholders toward the development of guidelines for inferring genetic ancestry in academia and industry. This report shares the stakeholder groups' work and provides an analysis of, commentary on, and views from the groundbreaking and sustained dialogue. We describe the engagement processes and the stakeholder groups' resulting statements and proposed guidelines. The guidelines focus on five key areas: application of genetic ancestry inference, assumptions and confidence/laboratory and statistical methods, terminology and population identifiers, impact on individuals and groups, and communication or translation of genetic ancestry inferences. We delineate the terms and limitations of the guidelines and discuss their critical role in advancing the development and implementation of best practices for inferring genetic ancestry and reporting the results. These efforts should inform both governmental regulation and self-regulation.

Bidirectional dispersals during the peopling of the North American Arctic

It is thought that Paleo-Inuit were the first people that settled the American Arctic about 5000 BP (before the present) from a migration that crossed Beringia from Northeast Asia. It is theorized that this group initially migrated to the North Slopes of Alaska and subsequently expanded eastward, eventually reaching Greenland. A second circumpolar dispersal of Neo-Inuit from the North Slopes associated with the Thule-Inuk culture has been postulated to have extended eastward around 800 BP, totally replacing the original Paleo-Inuit without admixing. Although generally accepted, this migration scenario is incompatible with previously reported indications of east to west gene flow across the American Arctic. Here we report on the Y-chromosome haplogroup and Y-STR diversity of the four circumpolar populations of the Tuva Republic (N = 24), Northeast Siberia (N = 9), Bethel, Alaska (N = 40), and Barrow, Alaska (N = 31). Four haplogroup lineages (Q-NWT01, Q-M3, Q-M346, and Q-M120) were detected, Q-NWT01 and Q-M3 being the most abundant at 11.11 and 66.67% in Northeast Siberia, 32.50 and 65.00% in Bethel, and 67.74 and 32.26% in Barrow, respectively. The same samples genotyped for Y-chromosome SNPs were typed for 17 Y-STYR loci using the AmpFlSTR Yfiler system. Age estimates and diversity values for the Q-NWT01 and Q-M3 mutations suggest extensive movement of male individuals along the entire longitudinal stretch of the American circumpolar region. Throughout the entire region, Q-M3 exhibits a west to east decreasing gradient in age and diversity while Q-NWT01 indicates the opposite with older TMRCA and higher diversity values running from east to west with the most recent estimates in Canada and Alaska. The high age and diversity values in Greenland are congruent with an origin of the Q-NWT01 mutation in the east of the circumpolar range about 2000-3000 ya. This scenario is incompatible with a complete biological replacement starting about 700 BP of Paleo-Inuit like the Dorset by the Thule-Inuit (Neo-Inuit), as is currently thought, and more parsimonious with gene flow carrying the NWT01 mutation from a pre-Thule population to the ancestors of the present-day Inuit.

The association between suicidal behaviour and violence, sexual abuse, and parental substance abuse among Sami and Greenlandic adolescents: the WBYG study and the NAAHS

Background

For young Indigenous people, suicide is one of the leading causes of death, and high rates in Arctic areas indicate serious health and societal concerns. More knowledge is needed, as suicidal behaviour predicts later death by suicide. The aim of this study was to investigate associations between suicidal thoughts and suicide attempts and negative life events, including violence, sexual abuse, and parental substance abuse, in Sami and Greenlandic adolescents, within and between groups and gender.

Method

Working samples included 442 Sami and 399 Greenlandic Inuit (15-16-year-olds), in The Norwegian Arctic Adolescent Health Study (NAAHS) and the Well-Being among Youth in Greenland (WBYG) study. Multivariable logistic regression explored associations between suicidal behaviour and violence, sexual abuse, and parental substance abuse.

Results

Across Indigenous groups, suicidal thoughts and attempts were significantly associated with violence and sexual abuse. The association between suicidal behaviour; especially suicidal thoughts, and sexual abuse was significant and strong among Sami females. Sami and Inuit adolescents with a history of childhood violence reported significantly more suicide attempts; the strongest association was found among Sami males.

Conclusion

To Sami and Greenlandic Inuit, the experiences of negative life events, such as violence or sexual abuse are significant risk factors for suicidal behaviour. Public health programmes and prevention strategies targeting youth mental health and suicide should be culturally sensitive and sensitive to gender differences in the association between negative life events and suicidal behaviour.

Ancient DNA provides insights into 4,000 years of resource economy across Greenland

The success and failure of past cultures across the Arctic was tightly coupled to the ability of past peoples to exploit the full range of resources available to them. There is substantial evidence for the hunting of birds, caribou and seals in prehistoric Greenland. However, the extent to which these communities relied on fish and cetaceans is understudied because of taphonomic processes that affect how these taxa are presented in the archaeological record. To address this, we analyse DNA from bulk bone samples from 12 archaeological middens across Greenland covering the Palaeo-Inuit, Norse and Neo-Inuit culture. We identify an assemblage of 42 species, including nine fish species and five whale species, of which the bowhead whale (Balaena mysticetus) was the most commonly detected. Furthermore, we identify a new haplotype in caribou (Rangifer tarandus), suggesting the presence of a distinct lineage of (now extinct) dwarfed caribou in Greenland 3,000 years ago.

A novel splice-affecting HNF1A variant with large population impact on diabetes in Greenland

Background

The genetic disease architecture of Inuit includes a large number of common high-impact variants. Identification of such variants contributes to our understanding of the genetic aetiology of diseases and improves global equity in genomic personalised medicine. We aimed to identify and characterise novel variants in genes associated with Maturity Onset Diabetes of the Young (MODY) in the Greenlandic population.

Methods

Using combined data from Greenlandic population cohorts of 4497 individuals, including 448 whole genome sequenced individuals, we screened 14 known MODY genes for previously identified and novel variants. We functionally characterised an identified novel variant and assessed its association with diabetes prevalence and cardiometabolic traits and population impact.

Findings

We identified a novel variant in the known MODY gene HNF1A with an allele frequency of 1.9% in the Greenlandic Inuit and absent elsewhere. Functional assays indicate that it prevents normal splicing of the gene. The variant caused lower 30-min insulin (β = -232 pmol/L, β_SD = -0.695, P = 4.43 × 10^-4) and higher 30-min glucose (β = 1.20 mmol/L, β_SD = 0.441, P = 0.0271) during an oral glucose tolerance test. Furthermore, the variant was associated with type 2 diabetes (OR 4.35, P = 7.24 × 10^-6) and HbA1c (β = 0.113 HbA1c%, β_SD = 0.205, P = 7.84 × 10^-3). The variant explained 2.5% of diabetes variance in Greenland.

Interpretation

The reported variant has the largest population impact of any previously reported variant within a MODY gene. Together with the recessive TBC1D4 variant, we show that close to 1 in 5 cases of diabetes (18%) in Greenland are associated with high-impact genetic variants compared to 1-3% in large populations.

Funding

Novo Nordisk Foundation, Independent Research Fund Denmark, and Karen Elise Jensen's Foundation.

An LDLR missense variant poses high risk of familial hypercholesterolemia in 30% of Greenlanders and offers potential of early cardiovascular disease intervention

The common Arctic-specific LDLR p.G137S variant was recently shown to be associated with elevated lipid levels. Motivated by this, we aimed to investigate the effect of p.G137S on metabolic health and cardiovascular disease risk among Greenlanders to quantify its impact on the population. In a population-based Greenlandic cohort (n = 5,063), we tested for associations between the p.G137S variant and metabolic health traits as well as cardiovascular disease risk based on registry data. In addition, we explored the variant’s impact on plasma NMR measured lipoprotein concentration and composition in another Greenlandic cohort (n = 1,629); 29.5% of the individuals in the cohort carried at least one copy of the p.G137S risk allele. Furthermore, 25.4% of the heterozygous and 54.7% of the homozygous carriers had high levels (>4.9 mmol/L) of serum LDL cholesterol, which is above the diagnostic level for familial hypercholesterolemia (FH). Moreover, p.G137S was associated with an overall atherosclerotic lipid profile, and increased risk of ischemic heart disease (HR [95% CI], 1.51 [1.18–1.92], p = 0.00096), peripheral artery disease (1.69 [1.01–2.82], p = 0.046), and coronary operations (1.78 [1.21–2.62], p = 0.0035). Due to its high frequency and large effect sizes, p.G137S has a marked population-level impact, increasing the risk of FH and cardiovascular disease for up to 30% of the Greenlandic population. Thus, p.G137S is a potential marker for early intervention in Arctic populations.

The Tibetan-Yi region is both a corridor and a barrier for human gene flow

The Tibetan-Yi Corridor (TYC) region between Tibet and the rest of east Asia has served as a crossroads for human migrations for thousands of years. The lack of whole-genome sequencing data specific to the TYC populations has hindered the understanding of the fundamental patterns of migration and divergence between humans in east Asia and southeast Asia. Here, we provide 248 individual whole genomes from the 16 TYC and 3 outgroup populations to elucidate historical relationships. We find that the Tibetan plateau forms an important barrier to gene flow, with a more Tibetan-like ancestry in northern populations and a southern east Asian-related ancestry in south populations. An isolated population, Achang, shows a prolonged isolation and genetic drift compared to other TYC populations. We also note that previous claims regarding the history and structure of TYC populations inferred by linguistics are incompatible with the genetic evidence.

Social determinants of dietary patterns, food basket costs and expenditure on alcohol and tobacco amongst Greenland Inuit

OBJECTIVE

Dietary transition, obesity and risky use of alcohol and tobacco are challenges to public health among indigenous peoples. The aim of the article was to explore the role of social position in dietary patterns and expenditures on food and other commodities.

DESIGN

Countrywide population health survey.

SETTING

Greenland.

PARTICIPANTS

2436 Inuit aged 15+ years.

RESULTS

Less than half of the expenditures on commodities (43 %) were used to buy nutritious food, and the remaining to buy non-nutritious food (21 %), alcoholic beverages (18 %) and tobacco (18 %). Participants were classified according to five dietary patterns. The cost of a balanced diet and an unhealthy diet was similar, but the cost per 1000 kJ was higher and the energy consumption was lower for the balanced diet. Participants with low social position chose the unhealthy pattern more often than those with high social position (40 % v. 24 %; P < 0·0001), whereas those with high social position more often chose the balanced alternative. Participants with low social position spent less money on the total food basket than those with high social position but more on non-nutritious food, alcohol and tobacco.

CONCLUSIONS

Cost seems to be less important than other mechanisms in the shaping of social dietary patterns and the use of alcohol and tobacco among the Inuit in Greenland. Rather than increasing the price of non-nutritious food or subsidising nutritious food, socially targeted interventions and public health promotion regarding food choice and prevention of excessive alcohol use and smoking are needed to change the purchase patterns.

Hand grip strength and chair stand test amongst Greenlandic Inuit: reference values and international comparisons

Muscle strength is an important predictor for function and mortality among older adults. We measured hand grip strength among 1442 participants aged 15+ years and carried out a 30 second chair stand test among 786 participants aged 55+ years. Neither test has been carried out among the Inuit before. We present reference values for men and women as means with standard deviations and medians with 10^th, 25^th, 75^th and 90^th percentiles. Hand grip strength was higher among men than among women (means 45.2 kg and 25.8 kg; p < 0.0001), in linear regression analyses it increased with height (β_men = 0.69; β_women = 0.46), weight (β_men = 0.24; β_women = 0.08) and body mass index (β_men = 0.56; β_women = 0.24), and decreased with age (β_men = −0.49; β_women = −0.29) and Inuit genetic ancestry (β_men = −0.96; β_women = −0.59). Chair stand score showed similar associations with sex (mean score for men and women 13.8 and 11.5; p < 0.0001), age (β_men = −0.22; β_women = −0.20) and Inuit genetic ancestry (β_men = −0.38; β_women = −0.41). The hand grip strength of the Inuit was at the same level as in European and North American populations whereas chair stand score was lower than that of a mostly white US population.

Low prevalence of retinopathy among Greenland Inuit

To assess the prevalence of diabetic retinopathy (DR) among persons with diabetes and prediabetes participating in the 2018 Population Health Survey in Greenland (B2018), a follow-up survey of three previous health surveys. Participants were invited to a diabetes complication screening. We assessed the prevalence of DR using Optos Daytona Ultra-wide field fundus camera and assessed differences in prevalence according to demographic and clinical characteristics using chi square test and a t-test and assessed DR based on ethnicity. The overall prevalence of DR was 2% (10/483). Among participants with HbA₁c ≥48 mmol/mol (6.5%) DR prevalence was 9% (9/91), compared with <1% (1/382) among participants with HbA₁c <48 mmol/mol (6.5%). All participants with DR lived in towns. The mean Inuit genetic admixture was lower among participants with DR. The prevalence of DR is low in Greenland and almost non-existent among persons with HbA₁c below the diabetes threshold.

Diet and physical activity in Greenland: genetic interactions and associations with obesity and diabetes

The Inuit in Greenland have gone through dramatic lifestyle changes during the last half century. More time is spent being sedentary and imported foods replaces traditional foods like seal and whale. The population has also experienced a rapid growth in obesity and metabolic disturbances and diabetes is today common despite being almost unknown few decades ago. In this paper, we describe and discuss the role of lifestyle changes and genetics for Inuit metabolic health. Novelty: Cardiometabolic disease risk has increased in Greenland. Lifestyle changes and possibly gene-lifestyle interactions play a role.

Association of food insecurity with dietary patterns and expenditure on food, alcohol and tobacco amongst indigenous Inuit in Greenland: results from a population health survey

BACKGROUND

Amongst the indigenous Greenlandic Inuit, the experience of food insecurity has been attributed to a lack of money to buy enough food of sufficient quality to sustain a family, although a preference for alcohol and tobacco over food has also been cited. The purpose of the article was to compare dietary patterns and expenditure on food, alcoholic beverages and tobacco between survey participants who reported food insecurity and those who did not.

METHODS

A countrywide cross-sectional health survey was carried out among 1886 adult Greenlandic Inuit in 2018. Diet was estimated by a food frequency questionnaire. Food insecurity status was based on the household hunger scale. Analyses were carried out by univariate general linear models adjusted for age, sex and social position.

RESULTS

Nine percent of the participants reported food insecurity. Food insecurity was higher among younger participants, men and participants with low social position. Food insecure participants more often chose an unhealthy dietary pattern (43% vs. 32%) and they reported a higher energy intake. The food insecure spent the same amount of money on food as other participants but less on nutritious food and more on non-nutritious food. The cost per kilojoule (kJ) of the food of the food insecure was lower than that of the food secure (DKK 8.0 and 9.0 per 1000 kJ, respectively). The food insecure participants also spent considerably more on alcohol and tobacco.

CONCLUSIONS

The results suggest that it is not only unemployment and lack of money that creates food insecurity and unhealthy dietary patterns in Greenland. Food insecure participants gave higher priority to buying non-nutritious food, alcohol and tobacco than did food secure participants. There seems to be at least two population subgroups in Greenland with poverty and substance use, respectively, as the immediate determinants for food insecurity. The results are important for the design of interventions against food insecurity and unhealthy dietary patterns.

The genetic history of Greenlandic-European contact

The Inuit ancestors of the Greenlandic people arrived in Greenland close to 1,000 years ago.¹ Since then, Europeans from many different countries have been present in Greenland. Consequently, the present-day Greenlandic population has ~25% of its genetic ancestry from Europe.² In this study, we investigated to what extent different European countries have contributed to this genetic ancestry. We combined dense SNP chip data from 3,972 Greenlanders and 8,275 Europeans from 14 countries and inferred the ancestry contribution from each of these 14 countries using haplotype-based methods. Due to the rapid increase in population size in Greenland over the past ~100 years, we hypothesized that earlier European interactions, such as pre-colonial Dutch whalers and early German and Danish-Norwegian missionaries, as well as the later Danish colonists and post-colonial immigrants, all contributed European genetic ancestry. However, we found that the European ancestry is almost entirely Danish and that a substantial fraction is from admixture that took place within the last few generations.

The Greenlandic Inuit have had extensive historical contact with Europeans, and the present-day Greenlandic population has substantial amounts of European ancestry. Waples et al. use genetic data to investigate the origin of this ancestry. They show that much of it is Danish and find little evidence of it being from pre-colonial European contact.

Socio-demographic, psychosocial and environmental factors associated with suicidal behaviour in Indigenous Sami and Greenlandic Inuit adolescents; the WBYG and NAAHS studies

Background. For young Indigenous people, suicide is one of the leading causes of death, and high rates in Arctic areas indicate serious health- and societal concerns. More knowledge is needed, as suicidal behaviour predictslater death by suicide.Objectives. The objective was to study associations between suicidal thoughts and suicide attempts and socio-demographic, psychosocial, and environmental factors in Sami and Greenlandic adolescents, within and between groups and gender.Methods. Working samples included 442 Sami and 399 Greenlandic Inuit (15-16-year-olds), in "The Norwegian Arctic Adolescent Health Study" (NAAHS) and "Well-being among Youth in Greenland" (WBYG). Multivariable logistic regression explored associations between suicidal behaviour and family , ethnic language , school, friendship, and suicide in close relations.Results. Across Indigenous groups, suicidal behaviour was associated with the female gender, relationships with parents, suicide of friends, and rural living. Sami adolescents in stepparent families reported more suicidal behaviour. Inuit adolescents living outside the family and with poor school performance reported more suicidal thoughts. Inuit adolescents spending less time with friends reported more attempts. Gender differences occurred in both groups.Conclusion. To Sami and Greenlandic Inuit, family and peer relations are important factors of suicidal behaviour. Prevention programmes should be sensitive to gender and bereavement.

The role of a traditional and western diet on glucose homeostasis in Greenlandic Inuit carriers and non-carriers of type 2 diabetes variant in the TBC1D4 gene: A protocol for a randomized clinical trial

INTRODUCTION

The lifestyle of Inuit in Greenland and worldwide is undergoing a transition from a fisher-hunter to a westernized society and meanwhile the prevalence of type-2 diabetes (T2D) has increased dramatically. Studies have shown that a common nonsense p.Arg684Ter variant in TBC1D4, which is frequent in Greenland, confers genetic susceptibility towards high risk of T2D. The aim of the study is to investigate whether a traditional marine diet, with high fat and low carbohydrate, will improve glycemic control in Greenland Inuit compared to a western diet. Moreover, we want to examine if the response is more pronounced in carriers of the p.Arg684Ter variant.

MATERIALS AND METHODS

We will conduct a randomized, clinical cross-over trial with two dietary intervention periods of four weeks duration. The diet intervention comprise provision of >20E% and instruction for the remaining part of the diet. We expect to include 30 homozygous carriers and 30 homozygous non-carriers of the p.Arg684Ter variant, aged 18-80 years, across three Greenlandic towns. The primary outcome is plasma (p)-glucose 2 h post an oral glucose tolerance test and we aim to have 80% power, at α = 0.05, to detect a difference of 1.1 mmol/L. We will also include supporting measures of glucose homeostasis, assess other markers of the metabolic syndrome and perform metabolome and microbiome profiling. The statistical analysis will be performed as complete case analyses using linear mixed models.

ETHICS AND DISSEMINATION

The study received approval by the Ethics Committee of Greenland (KVUG 2018-26) and will be disseminated via international peer-reviewed journal articles and conferences.

TRIAL REGISTRATION NUMBER

Clinicaltrials.gov identifier no. NCT04011904.

The effect of diabetes and the common diabetogenic TBC1D4 p.Arg684Ter variant on cardiovascular risk in Inuit in Greenland

Cardiovascular disease (CVD) is a well-known complication of diabetes, but the association has not been studied among Inuit in Greenland. The aim was to examine the association between diabetes and incident CVD among Inuit in Greenland and determine if the common diabetogenic TBC1D4 variant confers increased risk of CVD. We followed an initial study population of 4127 adults in Greenland who had participated in at least one population-based health survey, in national registers. We used Poisson regression to calculate incidence rate ratios (IRR) of cardiovascular endpoints, comparing participants with and without diabetes and comparing homozygous TBC1D4 carriers with heterozygous carriers and non-carriers combined. Close to 10% had diabetes and age range was 18-96 years (45% male). Of the 3924 participants without prior CVD, 362 (~ 9%) had CVD events during a median follow-up of 10 years. Multivariate IRR for the effect of diabetes on CVD was 1.12 (95% CI: 0.80, 1.57) p = 0.50. Using a recessive genetic model, we compared homozygous TBC1D4 carriers with wildtype and heterozygous carriers combined, with a multivariate IRR of 1.20 (95% CI: 0.69, 2.11) p = 0.52. Neither diabetes nor the TBC1D4 variant significantly increased CVD risk among Inuit in Greenland in adjusted models.

No association between early maternal HbA1c and offspring birthweight among women without pre-existing diabetes in Greenland

Studies of the association between maternal blood glucose measured by glycated haemoglobin (HbA1c) during pregnancy and the offspring’s birthweight have been heterogeneous. The aim of this study was to examine the association between maternal HbA1c level before gestational week 20 and the offspring’s birthweight among predominantly indigenous women in Greenland. A retrospective cohort study including all women (n = 503) and their offspring delivered from September 2015 to September 2016 at Queen Ingrid’s Hospital in Nuuk was conducted. Data were obtained from the electronic medical record. Linear regression models were used to analyse the effect of maternal HbA1c on the offspring’s birthweight with adjustment and stratification for relevant confounders and effect modifiers. Birthweight increased with 3.3 g per mmol/mol increase in HbA1c. Yet, no significant association between maternal HbA1c and the offspring’s birthweight was found after adjustment for maternal age, ethnicity, residence, smoking, and parity (β = 0.058, p = 0.711). Among obese women, a borderline significant positive association (β = 0.657, p = 0.059) was found. For term newborns, this corresponded to an increase in birthweight of 31 g per mmol/mol increase in HbA1c. Based on the current study, the use of HbA1c during pregnancy to detect the risk of delivering a newborn with macrosomia is not recommended in Greenland.

Abbreviation: HbA1c: glycosylated haemoglobin; GA: gestational age; SD: standard deviation; CI: confidence interval.

Disparities amidst plenty: a health portrait of Indigenous peoples in circumpolar regions

This paper describes the extent and variation in health disparities between Indigenous and non-Indigenous people within Alaska, Greenland and the northern regions of Canada, Russia and the Nordic countries. We accessed official health statistics and reviewed research studies. We selected a few indicators of health status, health determinants and health care to demonstrate the health disparities that exist. For a large number of health indicators Indigenous people fare worse than non-Indigenous people in the same region or nationally, with the exception of the Sami in the Nordic countries whose health profiles are similar to their non-Sami neighbours. That we were unable to produce a uniform set of indicators applicable to all regions is indicative of the large knowledge gaps that exist. The need for ongoing health monitoring for Indigenous people is most acute for the Sami and Russia, less so for Canada, and least for Alaska, where health data specific to Alaska Natives are generally available. It is difficult to produce an overarching explanatory model for health disparities that is applicable to all regions. We need to seek explanation in the broader political, cultural and societal contexts within which Indigenous people live in their respective regions.

Genetic study of the Arctic CPT1A variant suggests that its effect on fatty acid levels is modulated by traditional Inuit diet

Several recent studies have found signs of recent selection on the carnitine palmitoyl-transferase 1A (CPT1A) gene in the ancestors of Arctic populations likely as a result of their traditional diet. CPT1A is involved in fatty acid transportation and is known to affect circulating fatty acid profiles in Inuit as does the unique traditional diet rich in marine animals. We aimed to assess which fatty acids may have driven the selection of rs80356779, a c.1436C>T (p.(Pro479Leu)) variant in CPT1A, by analyzing a potential interaction between the variant and traditional Inuit diet. We included 3005 genome-wide genotyped individuals living in Greenland, who had blood cell membrane fatty acid levels measured. Consumption of 25 traditional food items was expressed as percentage of total energy intake. We tested for CPT1A × traditional diet interaction while taking relatedness and admixture into account. Increasing intakes of traditional diet was estimated to attenuate the effect of 479L on 20:3 omega-6 levels (p = 0.000399), but increase the effect of the variant on 22:5 omega-3 levels (p = 0.000963). The 479L effect on 22:5 omega-3 more than doubled in individuals with a high intake of traditional diet (90% percentile) compared with individuals with a low intake (10% percentile). Similar results were found when assessing interactions with marine foods. Our results suggest that the association between traditional diet and blood cell fatty acid composition is affected by the CPT1A genotype, or other variants in linkage disequilibrium, and support the hypothesis that omega-3 fatty acids may have been important for adaptation to the Arctic diet.

Alcohol in Greenland 1950-2018: consumption, drinking patterns, and consequences

Alcohol is the single most important public health challenge in Greenland. We provide an overview of alcohol consumption, drinking patterns, and consequences of excessive use of alcohol in Greenland since 1950 through a synthesis of published results and analyses of population-based interview surveys. The import of alcohol fluctuated over the last 70 years with a peak in the 1980s at 22 litres 100% alcohol per person per year. In 1950 and 2015, the import of alcohol was similar at 8 litres. Several explanations have been put forward to explain the changes including restrictions, increased tax, demographic changes, treatment of alcohol disorders, and public health interventions. The proportion of abstainers increased from 1993 to 2018 while the proportion of participants with regular consumption decreased. About half of the population reported binge drinking at least monthly. Compared with Denmark, there were more abstainers and binge drinkers in Greenland, and fewer had a regular consumption. Although genetics may play a role for drinking patterns, social and cultural conditions are more important. Exposure to domestic alcohol problems and sexual abuse in childhood parallel the recorded import of alcohol and is a likely cause of transgenerational consequences such as youth suicides and alcohol problems.

Towards estimating the indigenous population in circumpolar regions

Despite the importance of indigenous people in the Arctic, there is no accurate estimate of their size and distribution. We defined indigenous people as those groups represented by the “permanent participants” of the Arctic Council. The census in Canada, Russia and the United States records status as an indigenous person. In Greenland, a proxy measure is place of birth supplemented by other information. For the Nordic countries we utilized a variety of sources including registered voters’ lists of the various Sami parliaments and research studies that established Sami cohorts. Overall, we estimated that there were about 1.13 million indigenous people in the northern regions of the 8 Member States of the Arctic Council. There were 8,100 Aleuts in Alaska and the Russian North; 32,400 Athabaskans in Alaska and northern Canada; 145,900 Inuit in Alaska, northern Canada and Greenland; 76,300 Sami in northern Norway, Sweden, Finland and Russia; and 866,400 people in northern Russia belonging to other indigenous groups. Different degrees and types of methodological problems are associated with estimates from different regions. Our study highlights the complexity and difficulty of the task and the considerable gaps in knowledge. We hope to spur discussion of this important issue which could ultimately affect strategies to improve the health of circumpolar peoples.

Estimating narrow-sense heritability using family data from admixed populations

Estimating total narrow-sense heritability in admixed populations remains an open question. In this work, we used extensive simulations to evaluate existing linear mixed-model frameworks for estimating total narrow-sense heritability in two population-based cohorts from Greenland, and compared the results with data from unadmixed individuals from Denmark. When our analysis focused on Greenlandic sib pairs, and under the assumption that shared environment among siblings has a negligible effect, the model with two relationship matrices, one capturing identity by descent and one capturing identity by state, returned heritability estimates close to the true simulated value, while using each of the two matrices alone led to downward biases. When phenotypes correlated with ancestry, heritability estimates were inflated. Based on these observations, we propose a PCA-based adjustment that recovers the true simulated heritability. We use this knowledge to estimate the heritability of ten quantitative traits from the two Greenlandic cohorts, and report differences such as lower heritability for height in Greenlanders compared with Europeans. In conclusion, narrow-sense heritability in admixed populations is best estimated when using a mixture of genetic relationship matrices on individuals with at least one first-degree relative included in the sample.

The derived allele of a novel intergenic variant at chromosome 11 associates with lower body mass index and a favorable metabolic phenotype in Greenlanders

The genetic architecture of the small and isolated Greenlandic population is advantageous for identification of novel genetic variants associated with cardio-metabolic traits. We aimed to identify genetic loci associated with body mass index (BMI), to expand the knowledge of the genetic and biological mechanisms underlying obesity. Stage 1 BMI-association analyses were performed in 4,626 Greenlanders. Stage 2 replication and meta-analysis were performed in additional cohorts comprising 1,058 Yup'ik Alaska Native people, and 1,529 Greenlanders. Obesity-related traits were assessed in the stage 1 study population. We identified a common variant on chromosome 11, rs4936356, where the derived G-allele had a frequency of 24% in the stage 1 study population. The derived allele was genome-wide significantly associated with lower BMI (beta (SE), -0.14 SD (0.03), p = 3.2x10-8), corresponding to 0.64 kg/m2 lower BMI per G allele in the stage 1 study population. We observed a similar effect in the Yup'ik cohort (-0.09 SD, p = 0.038), and a non-significant effect in the same direction in the independent Greenlandic stage 2 cohort (-0.03 SD, p = 0.514). The association remained genome-wide significant in meta-analysis of the Arctic cohorts (-0.10 SD (0.02), p = 4.7x10-8). Moreover, the variant was associated with a leaner body type (weight, -1.68 (0.37) kg; waist circumference, -1.52 (0.33) cm; hip circumference, -0.85 (0.24) cm; lean mass, -0.84 (0.19) kg; fat mass and percent, -1.66 (0.33) kg and -1.39 (0.27) %; visceral adipose tissue, -0.30 (0.07) cm; subcutaneous adipose tissue, -0.16 (0.05) cm, all p<0.0002), lower insulin resistance (HOMA-IR, -0.12 (0.04), p = 0.00021), and favorable lipid levels (triglyceride, -0.05 (0.02) mmol/l, p = 0.025; HDL-cholesterol, 0.04 (0.01) mmol/l, p = 0.0015). In conclusion, we identified a novel variant, where the derived G-allele possibly associated with lower BMI in Arctic populations, and as a consequence also leaner body type, lower insulin resistance, and a favorable lipid profile.

Self-reported hearing impairment among Greenlandic adolescents: Item development and findings from the Health Behaviour in School-aged Children study 2018

OBJECTIVES

Ear infections are the leading cause of hearing impairment among children worldwide and a major public health problem in many indigenous populations, yet representative studies of self-reported hearing impairment are currently scarce. The purpose of the present study was therefore two-sided; first to develop an item bank for the collection of data on hearing impairment among Greenlandic adolescents, and second to report data on the child reports on hearing impairment from a national questionnaire-based survey.

METHODS

The study describes the process of developing items measuring hearing impairment among schoolchildren, and reports data for their inclusion into a national questionnaire survey. The data formed part of the Health Behaviour in School-aged Children (HBSC Greenland) 2018 survey including 2,273 students, corresponding to 47.6% of all Greenlandic schoolchildren in the age range from 10 to 16 years. Data analyses performed describe the data characteristics and the frequency of self-reported hearing impairment among Greenlandic schoolchildren. Binary logistic regression examined the associations of hearing impairment on school-related (risk) factors and self-rated health.

RESULTS

An average of 4% reported experiencing ear pain almost daily, and almost 10% reported ear pain at least weekly. Moreover, 3% reported having inflammation in the ear at least weekly, and 5% reported to have such impaired hearing that they were not at all able to follow what happened in school. Logistic regression showed that girls had significantly higher odds of low self-rated health, poor school environment and academic achievement below average when they had experienced impaired hearing. All ORs were statistically significant, varying from 1.85 (95% CI: 1.16-2.94) for low self-rated health, to 3.05 (95% CI 1.83-5.11) for feeling pressured by schoolwork. For boys the only significant association with impaired hearing was an academic achievement below average of 1.73 (95% CI 1.08-2.77).

CONCLUSIONS

The study confirms clinical knowledge and case studies that there are a significant proportion of Greenlandic adolescents who have experienced impaired hearing. Future studies may use questionnaire data to follow up on children with hearing impairment to be able to report changes over time and associations to school-related and social factors.

Genetic architecture and adaptations of Nunavik Inuit

The Canadian Inuit have a distinct population background that may entail particular implications for the health of its individuals. However, the number of genetic studies examining this Inuit population is limited, and much remains to be discovered in regard to its genetic characteristics. In this study, we generated whole-exome sequences and genomewide genotypes for 170 Nunavik Inuit, a small and isolated founder population of Canadian Arctic indigenous people. Our study revealed the genetic background of Nunavik Inuit to be distinct from any known present-day population. The majority of Nunavik Inuit show little evidence of gene flow from European or present-day Native American peoples, and Inuit living around Hudson Bay are genetically distinct from those around Ungava Bay. We also inferred that Nunavik Inuit have a small effective population size of 3,000 and likely split from Greenlandic Inuit ∼10.5 kya. Nunavik Inuit went through a bottleneck at approximately the same time and might have admixed with a population related to the Paleo-Eskimos. Our study highlights population-specific genomic signatures in coding regions that show adaptations unique to Nunavik Inuit, particularly in pathways involving fatty acid metabolism and cellular adhesion (CPNE7, ICAM5, STAT2, and RAF1). Subsequent analyses in selection footprints and the risk of intracranial aneurysms (IAs) in Nunavik Inuit revealed an exonic variant under weak negative selection to be significantly associated with IA (rs77470587; P = 4.6 × 10^-8).

Nicotinamide and Demographic and Disease transitions: Moderation is Best

Good health and rapid progress depend on an optimal dose of nicotinamide. Too little meat triggers the neurodegenerative condition pellagra and tolerance of symbionts such as tuberculosis (TB), risking dysbioses and impaired resistance to acute infections. Nicotinamide deficiency is an overlooked diagnosis in poor cereal-dependant economies masquerading as 'environmental enteropathy' or physical and cognitive stunting. Too much meat (and supplements) may precipitate immune intolerance and autoimmune and allergic disease, with relative infertility and longevity, via the tryptophan-nicotinamide pathway. This switch favours a dearth of regulatory T (Treg) and an excess of T helper cells. High nicotinamide intake is implicated in cancer and Parkinson's disease. Pro-fertility genes, evolved to counteract high-nicotinamide-induced infertility, may now be risk factors for degenerative disease. Moderation of the dose of nicotinamide could prevent some common diseases and personalised doses at times of stress or, depending on genetic background or age, may treat some other conditions.

Associations between birth weight and glucose intolerance in adulthood among Greenlandic Inuit

AIMS

To examine the association between birth weight and glucose intolerance in adult Greenlandic Inuit.

METHODS

We examined 1429 participants aged 18-56 years from two population-based, cross-sectional studies in Greenland with information on birth weight. Oral glucose tolerance tests, anthropometric measures and ultrasound of abdominal tissue were performed. Associations of birth weight with glucose markers were analysed using linear or logistic regressions. Spline analyses were conducted to examine u-shaped associations. Adjustments were done for age, sex, birth place, family history of diabetes, genetic admixture, TBC1D4 p.Arg684Ter carrier status, BMI and visceral adipose tissue.

RESULTS

The median birthweight was 3300 g and 3.9% had type 2 diabetes, T2DM. Spline analyses indicated overall linear associations. In fully adjusted analyses, an increase in birth weight of 1 kg was associated with a change in fasting plasma glucose of -0.06 mmol/L (95%CI: -0.11, -0.01), 2-h plasma glucose of -0.16 mmol/L (95%CI: -0.35, 0.02), HOMA-IR of -5.45% (95%CI: -10.34, -0.29), insulin sensitivity index of 7.04% (95%CI: 1.88, 12.45) and a trend towards a reduced risk of hyperglycaemia and T2DM, although statistically insignificant.

CONCLUSIONS

Birth weight was inversely associated with hepatic and peripheral insulin resistance independently of adult adiposity. Thus, the findings support low birth weight as a contributing factor for glucose intolerance in adult Inuit in Greenland.

Diabetes care in the dispersed population of Greenland. A new model based on continued monitoring, analysis and adjustment of initiatives taken

Diabetes used to be a rare condition among Inuit in Greenland. However, research in recent decades has shown a high prevalence of undiagnosed diabetes. Addressing diabetes in the geographically dispersed population of Greenland presents a challenge to the health care system. In 2008, a new model of diabetes care was introduced in Greenland that included continual monitoring, analysis, and adjustment of initiatives taken. The overall aim of this review was to review the feasibility of the monitoring of an ongoing national diabetes care programme. After ten years of observation it was clear that monitoring of such a programme based on information in electronic medical records in Greenland was feasible. It was found that the majority of the population in Greenland was in contact with the health care system. Increased diagnostic activity resulted in an increased prevalence of diagnosed diabetes. The quality of diabetes care in Greenland and the testing effectiveness of gestational diabetes were improved. Microvascular complications were frequently observed among Greenlandic diabetic patients, except for retinopathy that was as an exception. In summary, this model may improve diabetes care and potentially care for other chronic conditions in Greenland, and may also be helpful in other remote settings where chronic disease care is difficult.Abbreviations: AD: Anno Domini; ADA: American Diabetes Association; BC: Before Christ; BMI: Body Mass Index; BP: Blood Pressure; CWB: Capillary Whole Blood; EMR: Electronic Medical Record; EASD: European Association for Study of Diabetes; GA: Gestational Age; GDM: Gestational Diabetes Mellitus; FIGO: The International Federation of Gynaecology and Obstetrics; HbA1c: Glycosylated haemoglobin; IDF: International Diabetes Federation; LDL: Low density lipoprotein; NDQIA: National Diabetes Quality Improvement Alliancel; NICE: National Institute for Health and Care Excellence; OECD: Organisation for Economic Co-operation and Development; OGTT: Oral Glucose Tolerance Test; QIH: Queen Ingrid Hospital; RCT: Randomised Controlled Tria;l T1D: Type 1 Diabetes; T2D: Type 2 Diabetes; UACR: Urine Albumin Creatinine Ratio; WHO: World Health Organisation.

The Epidemiology of Suicide in Young Men in Greenland: A Systematic Review

Suicide is the leading cause of death among young men aged 15⁻29 in Greenland, but few epidemiological studies have described this problem. We aimed to summarise descriptive epidemiological studies of suicide in young men in Greenland compared with other demographic groups in Denmark and Greenland to inform future suicide prevention strategy. We searched PubMed, PsycINFO, and Embase using an agreed search strategy to identify English-language papers describing suicide epidemiology in Greenlandic men aged 15⁻29. We followed PRISMA guidelines in screening and appraising eligible publications. Eight articles fulfilled inclusion criteria of 64 meeting search criteria. Findings covering 1970⁻2011 supported a dramatic rise in suicide rates in Greenlandic men aged 15⁻24 from 1976, who remained the highest-ranking demographic group over 1976⁻2011 compared with men and women of all age groups in Denmark and Greenland. Highest rates recorded were almost 600 per 100,000 per year in men aged approximately 20⁻23 over 1977⁻1986. No studies described suicide epidemiology after 2011, and no studies described risk factors for suicide in young men. Given the very high suicide rates recorded for young men over 1976⁻2011, such studies will be essential for informing the development and evaluation of appropriate preventive interventions.

Genetics of metabolic traits in Greenlanders: lessons from an isolated population

In this review, we describe the extraordinary population of Greenland, which differs from large outbred populations of Europe and Asia, both in terms of population history and living conditions. Many years in isolation, small population size and an extreme environment have shaped the genetic composition of the Greenlandic population. The unique genetic background combined with the transition from a traditional Inuit lifestyle and diet, to a more Westernized lifestyle, has led to an increase in the prevalence of metabolic conditions like obesity, where the prevalence from 1993 to 2010 has increased from 16.4% to 19.4% among men, and from 13.0% to 25.4% among women, type 2 diabetes and cardiovascular diseases. The genetic susceptibility to metabolic conditions has been explored in Greenlanders, as well as other isolated populations, taking advantage of population-genetic properties of these populations. During the last 10 years, these studies have provided examples of loci showing evidence of positive selection, due to adaption to Arctic climate and Inuit diet, including TBC1D4 and FADS/CPT1A, and have facilitated the discovery of several loci associated with metabolic phenotypes. Most recently, the c.2433-1G>A loss-of-function variant in ADCY3 associated with obesity and type 2 diabetes was described. This locus has provided novel biological insights, as it has been shown that reduced ADCY3 function causes obesity through disrupted function in primary cilia. Future studies of isolated populations will likely provide further genetic as well as biological insights.

Measuring social inequality in health amongst indigenous peoples in the Arctic. A comparison of different indicators of social disparity among the Inuit in Greenland

The purpose of the article is to compare different indicators of social position as measures of social inequality in health in a population sample from an indigenous arctic people, the Inuit in Greenland. Data was collected during 2005-2015 and consisted of information from 3967 adult Inuit from towns and villages in all parts of Greenland. Social inequalities for smoking and central obesity were analysed in relation to seven indicators of social disparity in four dimensions, i.e. education and employment, economic status, sociocultural position, and place of residence. For each indicator we calculated age-adjusted prevalence by social group, rate ratio and the concentration index. The indicators were correlated with Pearson's r ranging from 0.24 to 0.82. Concentration indices ranged from 0.01 to 0.17. We could not conclude that one indicator was superior to others. Most of the indicators were traditional socioeconomic indicators used extensively in research in western countries and these seemed to be useful among the Inuit too, in particular household assets and job. Two sociocultural indicators developed for use among the Inuit and which included parameters specific to the indigenous peoples in the transition from a traditional to a modern life style proved to be equally useful but not superior to the traditional socioeconomic indicators. The choice of indicator must depend on what it is realistic to collect in the actual research setting and the use of more than one indicator is recommended. It is suggested to further develop culture specific indicators of social position for indigenous peoples.

Disequilibrium, Adaptation, and the Norse Settlement of Greenland

There is increasing evidence to suggest that arctic cultures and ecosystems have followed non-linear responses to climate change. Norse Scandinavian farmers introduced agriculture to sub-arctic Greenland in the late tenth century, creating synanthropic landscapes and utilising seasonally abundant marine and terrestrial resources. Using a niche-construction framework and data from recent survey work, studies of diet, and regional-scale climate proxies we examine the potential mismatch between this imported agricultural niche and the constraints of the environment from the tenth to the fifteenth centuries. We argue that landscape modification conformed the Norse to a Scandinavian style of agriculture throughout settlement, structuring and limiting the efficacy of seasonal hunting strategies. Recent climate data provide evidence of sustained cooling from the mid thirteenth century and climate variation from the early fifteenth century. Archaeological evidence suggests that the Norse made incremental adjustments to the changing sub-arctic environment, but were limited by cultural adaptations made in past environments.

Identification of novel high-impact recessively inherited type 2 diabetes risk variants in the Greenlandic population

AIMS/HYPOTHESIS

In a recent study using a standard additive genetic model, we identified a TBC1D4 loss-of-function variant with a large recessive impact on risk of type 2 diabetes in Greenlanders. The aim of the current study was to identify additional genetic variation underlying type 2 diabetes using a recessive genetic model, thereby increasing the power to detect variants with recessive effects.

METHODS

We investigated three cohorts of Greenlanders (B99, n = 1401; IHIT, n = 3115; and BBH, n = 547), which were genotyped using Illumina MetaboChip. Of the 4674 genotyped individuals passing quality control, 4648 had phenotype data available, and type 2 diabetes association analyses were performed for 317 individuals with type 2 diabetes and 2631 participants with normal glucose tolerance. Statistical association analyses were performed using a linear mixed model.

RESULTS

Using a recessive genetic model, we identified two novel loci associated with type 2 diabetes in Greenlanders, namely rs870992 in ITGA1 on chromosome 5 (OR 2.79, p = 1.8 × 10-8), and rs16993330 upstream of LARGE1 on chromosome 22 (OR 3.52, p = 1.3 × 10-7). The LARGE1 variant did not reach the conventional threshold for genome-wide significance (p < 5 × 10-8) but did withstand a study-wide Bonferroni-corrected significance threshold. Both variants were common in Greenlanders, with minor allele frequencies of 23% and 16%, respectively, and were estimated to have large recessive effects on risk of type 2 diabetes in Greenlanders, compared with additively inherited variants previously observed in European populations.

CONCLUSIONS/INTERPRETATION

We demonstrate the value of using a recessive genetic model in a historically small and isolated population to identify genetic risk variants. Our findings give new insights into the genetic architecture of type 2 diabetes, and further support the existence of high-effect genetic risk factors of potential clinical relevance, particularly in isolated populations.

DATA AVAILABILITY

The Greenlandic MetaboChip-genotype data are available at European Genome-Phenome Archive (EGA; https://ega-archive.org/ ) under the accession EGAS00001002641.

On the number of siblings and p-th cousins in a large population sample

The number of individuals in a random sample with close relatives in the sample is a quantity of interest when designing Genome Wide Association Studies and other cohort based genetic, and non-genetic, studies. In this paper, we develop expressions for the distribution and expectation of the number of p-th cousins in a sample from a population of size N under two diploid Wright-Fisher models. We also develop simple asymptotic expressions for large values of N. For example, the expected proportion of individuals with at least one p-th cousin in a sample of K individuals, for a diploid dioecious Wright-Fisher model, is approximately [Formula: see text]. Our results show that a substantial fraction of individuals in the sample will have at least a second cousin if the sampling fraction (K / N) is on the order of [Formula: see text]. This confirms that, for large cohort samples, relatedness among individuals cannot easily be ignored.

Genetic determinants of glycated hemoglobin levels in the Greenlandic Inuit population

We previously showed that a common genetic variant leads to a remarkably increased risk of type 2 diabetes (T2D) in the small and historically isolated Greenlandic population. Motivated by this, we aimed at discovering novel genetic determinants for glycated hemoglobin (HbA1C) and at estimating the effect of known HbA1C-associated loci in the Greenlandic population. We analyzed genotype data from 4049 Greenlanders generated using the Illumina Cardio-Metabochip. We performed the discovery association analysis by an additive linear mixed model. To estimate the effect of known HbA1C-associated loci, we modeled the effect in the European and Inuit ancestry proportions of the Greenlandic genome (EAPGG and IAPGG, respectively). After correcting for multiple testing, we found no novel significant associations. When we investigated loci known to associate with HbA1C levels, we found that the lead variant in the GCK locus associated significantly with HbA1C levels in the IAPGG ([Formula: see text]). Furthermore, for 10 of 15 known HbA1C loci, the effects in IAPGG were similar to the previously reported effects. Interestingly, the ANK1 locus showed a statistically significant ancestral population differential effect, with opposing directions of effect in the two ancestral populations. In conclusion, we found only 1 of the 15 known HbA1C loci to be significantly associated with HbA1C levels in the IAPGG and that two-thirds of the loci showed similar effects in Inuit as previously found in European and East Asian populations. Our results shed light on the genetic effects across ethnicities.

The tragedy of becoming tired of living: Youth and young adults' suicide in Greenland and Denmark

BACKGROUND

Suicide is a tremendous public health issue and worldwide the second leading cause of death among young people. In 2015, Greenland had the highest burden of disease due to self-harm with loss of 2,952.97 disability-adjusted life years per 100,000 inhabitants, more than six times as many as Denmark.

AIMS

What are possible reasons for Greenland's higher youth suicide rate compared to Denmark, despite being one kingdom of Denmark?

METHOD

Mixed methods in the form of qualitative, semi-structured interviews, the analysis of available data for 2003-2016 and a literature review were conducted with the aim to answer this question.

RESULTS

Several exposures cause this difference, most significantly adverse effects of the colonial past, such as social issues and experienced traumas in Greenland compared to its former coloniser Denmark.

CONCLUSION

The ongoing burden of youth suicide in Greenland requires enhanced actions of all stakeholders involved in suicide prevention, intervention and postvention.

Three lifestyle-related issues of major significance for public health among the Inuit in contemporary Greenland: a review of adverse childhood conditions, obesity, and smoking in a period of social transition

Greenland is a country in transition from a colonial past with subsistence hunting and fishing to an urban Nordic welfare state. Epidemiological transition from infectious to chronic diseases has been evident since the 1950s. Ninety percent of the population is Inuit.

We studied three public health issues based on published literature, namely adverse childhood experiences, addictive behavior, and suicide; diet and obesity; and smoking. Alcohol consumption was high in the 1970s and 1980s with accompanying family and social disruption. This is still a cause of poor mental health and suicides in the generations most affected. The diet is changing from a traditional diet of fish and marine mammals to imported food including food items rich in sugar and fat from domestic animals, and the level of physical activity is decreasing with an ensuing epidemic rise in obesity. The prevalence of smoking is high at around 60% among both men and women and is only slowly decreasing. Smoking shows large social variation, and tobacco-related diseases are widespread.

The diseases and conditions outlined above all contribute towards a low life expectancy at birth—69 years for men and 74 years for women in 2011–2015—compared with 78 and 84 years for men and women, respectively, on average in the European countries. The translation of government public health programs into local activities needs strengthening, and it must be realized that the improvement of public health is a long-term process.