Highly discrepant proportions of female and male Scandinavian and British Isles ancestry within the isolated population of the Faroe Islands

A nationwide registry-based observational study of thyroid disease incidence in the Faroe Islands

OBJECTIVE

The occurrence of thyroid disease varies among populations. While the iodine nutrition level of the Faroese seems to have been decreasing over the past decades, there is no systematic evaluation of the thyroid disease pattern in the Faroe Islands. Such knowledge of thyroid disease occurrence in the North Atlantic region may support healthcare planning and prevention. To investigate incidence rates, including subtypes of thyroid diseases, and demographic characteristics of thyroid disease patients in the Faroe Islands, to improve understanding of the patterns and trends of these disorders.

DESIGN AND METHOD

A registry-based observational study was conducted over 10 years, encompassing all adult Faroese individuals.

PATIENTS AND MEASUREMENTS

Health records from general practitioners and hospitals were used to identify incident cases of thyroid diseases. Validation was performed using multiple data sources. The incidence rates were standardised using population data from the middle of the study period 2006-2018.

RESULTS

Among the 1152 individuals diagnosed with thyroid disease, the standardised incidence rates per 100,000 person-years were 55 for hyperthyroidism and 112 for hypothyroidism, and around four times higher in women than in men. Hashimoto's thyroiditis was the dominant cause of hypothyroidism, while Graves' disease was the leading cause of hyperthyroidism. The incidence of hypothyroidism increases with age. A decreasing trend was observed over time for both hypothyroidism and hyperthyroidism.

CONCLUSION

Considering the decrease in iodine nutrition levels over the past decades, we were surprised by the high incidence of autoimmune thyroid disease. The findings highlight the need for continuous monitoring of thyroid disease occurrence in coastal areas of the North Atlantic Ocean.

10-Year Cognitive Change in the Faroese Septuagenarian Cohort and Impact of Sociodemographic, Lifestyle, and Health Factors

OBJECTIVES

To investigate cognitive change in multiple cognitive domains in a population-based cohort of 713 Faroese older adults.

METHODS

Participants were cognitively tested at baseline (70-74 years) and re-evaluated after 10 years. Changes in cognitive performance and the impact of sociodemographic factors, lifestyle, and health conditions were analysed using mixed-effect models. Participants free from dementia were studied in separate analyses.

RESULTS

A significant decline over 10 years was observed in most of the neuropsychological tests. People living in rural areas, married or cohabiting people, people without professional education, slightly older persons, smokers, teetotalers, and people with heart disease and abnormal electrocardiogram (ECG) had a steeper decline in cognitive ability. Conflicting results were found for sex and people with myocardial infarction (MI).

DISCUSSION

There are modifiable factors that contribute to cognitive decline which should be addressed in future public health efforts.

The Incidence and Prevalence of Inflammatory Bowel Disease Continues to Increase in the Faroe Islands - A Cohort Study from 1960 to 2020

BACKGROUND AND AIMS

The highest reported incidence rate of inflammatory bowel disease [IBD], and especially of ulcerative colitis [UC], is found in the Faroe Islands. This study aimed to assess the incidence rate and temporal trends in prevalence over six decades.

METHODS

All incident and prevalent patients diagnosed with IBD between 1960 and 2020 from the nationwide and population-based Faroese IBD cohort were included in this study. All patients fulfilled the Copenhagen Diagnostic Criteria.

RESULTS

Overall, 873 individuals were diagnosed with IBD during the study period, 559 [64%] with UC, 151 [17%] with Crohn's disease, and 163 [19%] with IBD unclassified. A total of 59 patients had paediatric-onset IBD. The incidence of IBD continued to increase throughout the study period, as the age-standardized incidence rate started at 8 per 100 000 person-years [py] [European Standard Population, ESP] in 1960-79 and reached 70 by 2010-20. In 2021, the age-standardized period prevalence was 1414 per 100 000 persons. The IBD incidence was unevenly distributed among the islands with Sandoy having the highest rate of 106 per 100 000 py in 2010-2020.

CONCLUSIONS

The incidence of IBD continues to increase in the Faroe Islands, mainly driven by UC. The incidence shows an uneven geographical distribution, which suggests an adverse interaction between unknown environmental factors and genetic traits. The prevalence in 2021 corresponded to 1.3% of the Faroese population. Environmental risk factors are suspected to impact this homogeneous high-risk population; however, the reason for this is unclear.

A nationwide study of autoimmune liver diseases in the Faroe Islands: Incidence, prevalence, and causes of death 2004 - 2021

Background and aims: Autoimmune liver diseases are rare diseases, and population-based studies on the epidemiology of autoimmune hepatitis (AIH), primary biliary cholangitis (PBC), and primary sclerosing cholangitis (PSC) are sparse. We aimed to assess the incidence of AIH, PBC, and PSC in the Faroe Islands.Methods: All cases of AIH, PBC, and PSC diagnosed in the Faroe Islands between January 1^st, 2004, and December 31^st, 2021, were included in this nationwide registry-based cohort study. In addition, we searched all medical records to assess diagnostic criteria and cause of death.Results: The incidences of AIH, PBC, and PSC in the Faroe Islands were 5.2, 2.5 and 0.7 per 100,000 population per year, respectively. Point prevalence per 100,000 population on December 31st 2021, was 71.8 for AIH, 38.5 for PBC, and 11.0 for PSC. Nine AIH patients died after a median of 3 years, three died of hepatocellular carcinoma (HCC), and two died of liver failure. Five PBC patients died after a median of 7 years, one of HCC and one of liver failure. One PSC patient died of cholangiocarcinoma.Conclusion: The incidence and prevalence of AIH, PBC and PSC in the Faroe Islands are among the highest reported in population-based settings.

SNP heterozygosity, relatedness and inbreeding of whole genomes from the isolated population of the Faroe Islands

BACKGROUND

The population of the Faroe Islands is an isolated population but very little is known about it from whole genome sequencing. The population of about 50000 people has a high incidence of rare diseases e.g., 1:300 for Primary Carnitine Deficiency. A screening programme was implemented, and eleven persons were also whole genome sequenced at x37 coverage for diagnostic purposes of those cases that were not affected by the known mutations. The purpose of our study is to utilize the high coverage data to explore the genomic variation and the ancestral history of the population. We study the SNP heterozygosity, the pairwise relatedness from kinship, the inbreeding from runs of homozygosity ROH, and we find the minor allele frequency distribution. We estimate the population ancestry and the timing of the founding event by using the whole genomes from eight consenting individuals.

RESULTS

We find the number of SNPs and the heterozygosity for the eight individual samples, and for merged samples, for which we also study the relatedness. We find close relatedness between the supposedly unrelated individuals. From ROH, we interpret the high relatedness as an ancient property of the isolated population. A bottleneck event is estimated starting between years [Formula: see text] with a maximum consanguineous population in year [Formula: see text] and similarly consanguineous between years [Formula: see text]. The ancestry analysis shows the population descends from founders of [Formula: see text] European and [Formula: see text] Admixed American ancestry. A distinct clustering near the central European and British populations of the 1000 Genome Project is likely the result of the population isolation and genetic drift. The minor allele frequency distribution suggests many rare variants.

CONCLUSIONS

The ancestry is mainly European while the inbreeding is higher compared to European populations and population isolates. The Faroese population has inbreeding more like ancient Europeans. We discovered a bottlenecked and consanguineous population event and estimated it starting in the 1st-4th century as compared to the oldest archaeological findings from the 4th-6th century.

Possible explanations for the common clinical familial hypercholesterolemia phenotypes in the Faroe Islands

BACKGROUND

The prevalence of clinical familial hypercholesterolemia (FH) is very high in the Faroe Islands, but the possible causes are unknown.

OBJECTIVES

We aimed to describe potential genetic causes of FH in the Faroe Islands and to investigate whether levels of lipoprotein(a) and measures of dietary habits were associated with clinical FH in the Faroe Islands.

METHODS

In this case-control study, we identified potential clinical FH cases aged 18-75 years registered within a nationwide clinical laboratory database in the Faroe Islands and invited them for diagnostic evaluation according to clinical FH scoring systems. Controls were identified in the background population. Lipoprotein(a) was measured in plasma, while the fatty acid composition was determined in adipose tissue. The habitual diet of the participants was assessed using a food frequency questionnaire. Genetic testing for FH and polygenic variants was performed in a selection of clinical FH cases.

RESULTS

A total of 121 clinical FH cases and 123 age- and sex-matched controls were recruited. We found a very low frequency of monogenic FH (2.5%), but a high level of polygenic FH (63%) in those genetically tested (67%). High levels of plasma lipoprotein(a) were associated with high odds of clinical FH. Clinical FH cases had a lower intake of saturated fatty acids (SFAs) measured by a high fat-score and a lower content of SFAs in adipose tissue compared with controls.

CONCLUSION

The high prevalence of FH in the Faroe Islands may be due to polygenic causes of hypercholesterolemia and to a lesser extent other genetic factors and elevated plasma lipoprotein(a) levels.

FarGen: Elucidating the distribution of coding variants in the isolated population of the Faroe Islands

Here we present results from FarGen Phase I exomes. This dataset is based on the FarGen cohort, which consists of 1,541 individuals from the isolated population of the Faroe Islands. The purpose of this cohort is to serve as a reference catalog of coding variants, and to conduct population genetic studies to better understand the genetic contribution to various diseases in the Faroese population. The first whole-exome data set comprise 465 individuals and a total of 148,267 genetic variants were discovered. Principle Component Analysis indicates that the population is isolated and weakly structured. The distribution of variants in various functional classes was compared with populations in the gnomAD dataset; the results indicated that the proportions were consistent across the cohorts, but probably due to a small sample size, the FarGen dataset contained relatively few rare variants. We identified 19 variants that are classified as pathogenic or likely pathogenic in ClinVar; several of these variants are associated with monogenetic diseases with increased prevalence in the Faroe Islands. The results support previous studies, which indicate that the Faroe Islands is an isolated and weakly structured population. Future studies may elucidate the significance of the 19 pathogenic variants that were identified. The FarGen Phase I dataset is an important step for genetic research in the Faroese population, and the next phase of FarGen will increase the sample size and broaden the scope.

Clinical characteristics of primary carnitine deficiency: A structured review using a case-by-case approach

A broad spectrum of signs and symptoms has been attributed to primary carnitine deficiency (PCD) since its first description in 1973. Advances in diagnostic procedures have improved diagnostic accuracy and the introduction of PCD in newborn screening (NBS) programs has led to the identification of an increasing number of PCD patients, including mothers of screened newborns, who may show a different phenotype compared to clinically diagnosed patients. To elucidate the spectrum of signs and symptoms in PCD patients, we performed a structured literature review. Using a case-by-case approach, clinical characteristics, diagnostic data, and mode of patient identification were recorded. Signs and symptoms were categorized by organ involvement. In total, 166 articles were included, reporting data on 757 individual patients. In almost 20% (N = 136) of the cases, the diagnosis was based solely on low carnitine concentration which we considered an uncertain diagnosis of PCD. The remaining 621 cases had a diagnosis based on genetic and/or functional (ie, carnitine transporter activity) test results. In these 621 cases, cardiac symptoms (predominantly cardiomyopathy) were the most prevalent (23.8%). Neurological (7.1%), hepatic (8.4%), and metabolic (9.2%) symptoms occurred mainly in early childhood. Adult onset of symptoms occurred in 16 of 194 adult patients, of whom 6 (3.1%) patients suffered a severe event without any preceding symptom (five cardiac events and one coma). In conclusion, symptoms in PCD predominantly develop in early childhood. Most newborns and mothers of newborns detected through NBS remain asymptomatic. However, though rarely, severe complications do occur in both groups.

Meiotic drive in chronic lymphocytic leukemia compared with other malignant blood disorders

The heredity of the malignant blood disorders, leukemias, lymphomas and myeloma, has so far been largely unknown. The present study comprises genealogical investigations of one hundred and twelve Scandinavian families with unrelated parents and two or more cases of malignant blood disease. For comparison, one large family with related family members and three hundred and forty-one cases of malignant blood disease from the Faroese population was included. The inheritance is non-Mendelian, a combination of genomic parental imprinting and feto-maternal microchimerism. There is significantly more segregation in maternal than in paternal lines, predominance of mother-daughter combinations in maternal lines, and father-son combinations in paternal lines. Chronic lymphocytic leukemia is the most frequent diagnosis in the family material, and chronic lymphocytic leukemia has a transgenerational segregation that is unique in that inheritance of susceptibility to chronic lymphocytic leukemia is predominant in males of paternal lines. Male offspring with chronic lymphocytic leukemia in paternal lines have a birth-order effect, which is manifest by the fact that there are significantly more male patients late in the sibling line. In addition, there is contravariation in chronic lymphocytic leukemia, i.e. lower occurrence than expected in relation to other diagnoses, interpreted in such a way that chronic lymphocytic leukemia remains isolated in the pedigree in relation to other diagnoses of malignant blood disease. Another non-Mendelian function appears in the form of anticipation, i.e. increased intensity of malignancy down through the generations and a lower age at onset of disease than otherwise seen in cases from the Cancer Registers, in acute lymphoblastic leukemia, for example. It is discussed that this non-Mendelian segregation seems to spread the susceptibility genes depending on the gender of the parents and not equally to all children in the sibling line, with some remaining unaffected by susceptibility i.e. "healthy and unaffected", due to a birth order effect. In addition, anticipation is regarded as a non-Mendelian mechanism that can amplify, «preserve» these vital susceptibility genes in the family. Perhaps this segregation also results in a sorting of the susceptibility, as the percentage of follicular lymphoma and diffuse large B-cell lymphoma is lower in the family material than in an unselected material. Although leukemias, lymphomas and myelomas are potentially fatal diseases, this non-Mendelian distribution and amplification hardly play any quantitative role in the survival of Homo sapiens, because these diseases mostly occur after fertile age.

Familial hypercholesterolaemia: a study protocol for identification and investigation of potential causes and markers of subclinical coronary artery disease in the Faroe Islands

INTRODUCTION

Familial hypercholesterolaemia (FH) is the most common monogenic autosomal dominant genetic disorder and is associated with a high risk of premature atherosclerotic cardiovascular disease. The prevalence of FH has been reported to be particularly high in certain founder populations. The population of the Faroe Islands is a founder population, but the prevalence of FH has never been investigated here. We aim to assess the prevalence of FH and to describe the genetic and clinical characteristics and potential causes of FH in the Faroe Islands. Furthermore, we aim to investigate whether indicators of subclinical coronary artery disease are associated with FH.

METHODS AND ANALYSIS

The prevalence of FH will be estimated based on an electronic nationwide laboratory database that includes all measurements of plasma lipid levels in the Faroe Islands since 2006. Subsequently, we will identify and invite subjects aged between 18 and 75 years registered with a plasma low-density lipoprotein cholesterol above 6.7 mmol/L for diagnostic evaluation. Eligible FH cases will be matched to controls on age and sex. We aim to include 120 FH cases and 120 controls.Detailed information will be collected using questionnaires and interviews, and a physical examination will be undertaken. An adipose tissue biopsy and blood samples for genetic testing, detailed lipid analyses and samples for storage in a biobank for future research will be collected. Furthermore, FH cases and controls will be invited to have a transthoracic echocardiography and a cardiac CT performed.

ETHICS AND DISSEMINATION

The project has been approved by the Ethical Committee and the Data Protection Agency of the Faroe Islands. The project is expected to provide important information, which will be published in international peer-reviewed journals.

Lipids, lipoproteins and prevalence of familial hypercholesterolemia in the Faroe Islands - Results from a nationwide laboratory database

BACKGROUND AND AIMS

Familial hypercholesterolemia (FH) is one of the most common hereditary disorders. The population of the Faroe Islands was established by few founders, and genetic drift may have influenced lipid levels. The aim of this study was to describe the lipid distribution by providing age and sex-specific lipid values and to investigate the prevalence of FH in the Faroe Islands.

METHODS

We used an electronic nationwide laboratory database that included lipid measurements obtained in the Faroe Islands between January 2006 and September 2020. Percentiles of lipid levels were calculated using quantile regression. The prevalence of FH was estimated according to the Make Early Diagnosis Prevent Early Death (MEDPED) diagnostic criteria and according to the LDL-C cut-off levels included in the Dutch Lipid Clinic Network (DLCN) criteria using generalized linear models with robust variance.

RESULTS

According to the MEDPED age-specific cut-offs for LDL-C, a total of 216 subjects met the criteria for definite FH among 30,711 individuals corresponding to a prevalence of 0.70% (1:142). According to the LDL-C cut-offs included in the DLCN criteria, a total of 3,823 (1:8) subjects could be classified as having possible FH, and 10 (1:3,071) subjects could be classified as probable FH corresponding to a prevalence of 12.4% and 0.03%, respectively. Also, we found significant differences in lipid levels according to sex and age groups.

CONCLUSION

The Faroe Islands might represent a founder population with a prevalence of possible FH as high as 1 in 8. Further investigation of genetic and clinical characteristics of FH in the Faroe Islands is needed.

Prevalence of Open-angle Glaucoma in the Faroese Population

PURPOSE

The Faroe Islands are home to 50,000 genetically isolated people in the North Atlantic. The prevalence of open-angle glaucoma (OAG) in the Faroese population is unknown. Consequently, we conducted a survey to determine the prevalence of OAG in the Faroese population. We also investigated the role of known glaucoma-causing genes in Faroese OAG.

MATERIALS AND METHODS

We conducted a prospective survey of known and newly diagnosed glaucoma patients at the Faroese National Hospital, Landssjukrahusid, Tórshavn between October 1, 2015 to December 31, 2017. In addition we reviewed the only eye care provider in the Faroese Islands by scrutinizing electronic medical records between 2009 and June 15, 2014, October 1, 2015 and the partly overlapping prescriptions for ocular hypotensive medications in 2016 to identify patients with either a diagnosis of glaucoma, a diagnosis of ocular hypertension or a prescription for ocular hypotensive medications. Next, we prospectively confirmed diagnoses with complete eye examinations. Patient DNA samples were tested for variations in known glaucoma-causing genes [myocilin (MYOC), optineurin (OPTN), and TANK binding kinase 1 (TBK1)].

RESULTS

We determined the age-related prevalence of OAG January 1, 2017 in individuals 40 years or older to be 10.7/1000 (1.07%) and highly age-related. A diagnosis of OAG was present in 264 patients, of whom 211 (79.9%) had primary OAG (including normal tension glaucoma), 49 (18.6%) had pseudoexfoliation glaucoma, and 4 (1.5%) had pigmentary glaucoma. Among patients receiving medications for glaucoma, nearly 50% had primary OAG, while the majority of the rest had ocular hypertension or secondary glaucoma. No disease-causing variants were detected in MYOC, OPTN, or TBK1.

CONCLUSIONS

The calculated prevalence of OAG in the Faroe Islands was 1.07%. The absence of MYOC, OPTN, or TBK1 disease-causing variants in Faroese primary OAG patients suggests that a different, potentially unique set of genes may be contributing to the pathogenesis of glaucoma in this population.

High incidence of amyotrophic lateral sclerosis in the Faroe Islands 2010-2020

The Faroese population isolate harbors epidemiological and genetic characteristics that likely differ from outbred populations. This population-based register study found that the Faroese 2010-2020 crude incidence of amyotrophic lateral sclerosis (ALS) was 4.9/100,000 person-years (95% confidence interval [CI], 3.3-7.0) and the age- and sex-standardized incidence (US 2010 Census Population) was 4.1/100,000 person-years (95% CI, 2.7-6.0), which is a 68% increase from the 1987-2009 estimate. The 2020 crude prevalence was 9.5/100,000 (95% CI, 3.0-19.6) in a population of 52,912 inhabitants. Incidence and prevalence estimates of ALS in the Faroes are high and further research is warranted to uncover the genetic or environmental determinants of ALS in this population.

FarGen - participants in the genetic research infrastructure of the Faroe Islands

Background: The demographic history of the Faroe Islands makes this isolated population – founded in the 9th century – interesting for genetic research. The goal of the FarGen project was to recruit individuals to the FarGen infrastructure to promote research into the genetic features of the Faroese people, and to develop a reference panel of population-specific variants. We aimed to recruit 1500 individuals. Participation was voluntary; participants had to donate a blood sample for whole-genome sequencing, and had to answer a questionnaire regarding sociodemographics, health, motivation and attitude towards participation in genetic research. Methods: A total of 1541 participants voluntarily joined the project, donated a blood sample and returned the questionnaire. Results: Answers from the questionnaire show that participants are, in general, European, have children, have a relatively high level of education, rate their health to be good, are willing to participate in future health-related research, and were motivated to sign up primarily to participate in research to help others and local research competency building. Conclusions: Overall, the initial cohort of the FarGen infrastructure comprises 3% of the Faroese population, and represents the general population well based on the collected sociodemographic data. However, there is an excess of women, and some geographic sub-regions and age groups are slightly underrepresented. We find the recruitment method with voluntary sign-up appropriate, and knowledge acquired through the first phase will aid the next phase of the project, with the aim of expanding the FarGen cohort with additional individuals, bio-specimens and body measurements in order to perform multifactorial analyses.

Novel Homozygous Truncating Variant Widens the Spectrum of Early-Onset Multisystemic SYNE1 Ataxia

Pathogenic variants in the SYNE1 gene are associated with a phenotypic spectrum spanning from late-onset, slowly progressive, relatively pure ataxia to early-onset, fast progressive multisystemic disease. Since its first description in 2007 as an adult-onset ataxia in French Canadian families, subsequent identification of patients worldwide has widened the clinical spectrum and increased the number of identified pathogenic variants. We report a 20-year-old Faroese female with early-onset progressive gait problems, weakness, dysphagia, slurred speech, orthostatic dizziness, and urge incontinence. Neurological examination revealed mild cognitive deficits, dysarthria, broken slow pursuit, hypometric saccades, weakness with spasticity, hyperreflexia, absent ankle reflexes, ataxia, and wide-based, spastic gait. Magnetic resonance imaging displayed atrophy of the cerebellum, brainstem, and spinal cord. Severely prolonged central motor conduction time and lower motor neuron involvement was demonstrated electrophysiologically. Fluorodeoxyglucose-positron emission tomography (FDG-PET) scan showed hypometabolism of the cerebellum and right frontal lobe. Muscle biopsy revealed chronic neurogenic changes and near-absent immunostaining for Nesprin-1. Next-generation sequencing revealed a previously undescribed homozygous truncating, likely pathogenic variant in the SYNE1 gene. The patient's mother and paternal grandfather were heterozygous carriers of the variant. Her father's genotype was unobtainable. We expand the list of likely pathogenic variants in SYNE1 ataxia with a novel homozygous truncating variant with proximity to the C-terminus and relate it to a phenotype comprising early-onset cerebellar deficits, upper and lower motor neuron involvement and cognitive deficits. Also, we report novel findings of focally reduced frontal lobe FDG-PET uptake and motor evoked potential abnormalities suggestive of central demyelination.

Human milk extracellular vesicle miRNA expression and associations with maternal characteristics in a population-based cohort from the Faroe Islands

Human milk plays a critical role in infant development and health, particularly in cognitive, immune, and cardiometabolic functions. Milk contains extracellular vesicles (EVs) that can transport biologically relevant cargo from mother to infant, including microRNAs (miRNAs). We aimed to characterize milk EV-miRNA profiles in a human population cohort, assess potential pathways and ontology, and investigate associations with maternal characteristics. We conducted the first study to describe the EV miRNA profile of human milk in 364 mothers from a population-based mother-infant cohort in the Faroe Islands using small RNA sequencing. We detected 1523 miRNAs with ≥ one read in 70% of samples. Using hierarchical clustering, we determined five EV-miRNA clusters, the top three consisting of 15, 27 and 67 miRNAs. Correlation coefficients indicated that the expression of many miRNAs within the top three clusters was highly correlated. Top-cluster human milk EV-miRNAs were involved in pathways enriched for the endocrine system, cellular community, neurodevelopment, and cancers. miRNA expression was associated with time to milk collection post-delivery, maternal body mass index, and maternal smoking, but not maternal parity. Future studies investigating determinants of human EV-miRNAs and associated health outcomes are needed to elucidate the role of human milk EV-miRNAs in health and disease.

The composition of the founding population of Iceland: A new perspective from 3D analyses of basicranial shape

The settlement of Iceland in the Viking Age has been the focus of much research, but the composition of the founding population remains the subject of debate. Some lines of evidence suggest that almost all the founding population were Scandinavian, while others indicate a mix of Scandinavians and people of Scottish and Irish ancestry. To explore this issue further, we used three-dimensional techniques to compare the basicrania of skeletons from archaeological sites in Iceland, Scandinavia, and the British Isles. Our analyses yielded two main results. One was that the founding population likely consisted of roughly equal numbers of Scandinavians and people from the British Isles. The other was that the immigrants who originated from the British Isles included individuals of southern British ancestry as well as individuals of Scottish and Irish ancestry. The first of these findings is consistent with the results of recent analyses of modern and ancient DNA, while the second is novel. Our study, therefore, strengthens the idea that the founding population was a mix of Scandinavians and people from the British Isles, but also raises a new possibility regarding the regions from which the settlers originated.

Trend in the Incidence and Prevalence of Dementia in the Faroe Islands

Background:

Dementia has become an important public health, economic, and social issue. Knowledge about prevalence, incidence, and trends of dementia in a country is of crucial importance. However, no studies of incidence or prevalence of dementia have been undertaken in the Faroe Islands.

Objectives:

The aim was to estimate the overall and trend in incidence and prevalence of dementia among individuals ≥60 years in the Faroe Islands from 2010-2017.

Methods:

Population-based register study where all individuals ≥60 years with a dementia diagnosis from January 2010 to December 2017 were identified. The overall crude and age-and-sex-specific incidence and prevalence was assessed.

Results:

The overall crude incidence among individuals ≥60 years from 2010 to 2017 was 5.1 per 1000 individuals and the prevalence 22.5 per 1000 individuals. The age-and sex-standardized annual incidence of dementia fluctuated between 4.8 and 6.7 per 1000, with no clear secular trend while the age-and sex-standardized prevalence increased steadily from 14.5 in 2010 to 30.8 per 1000 individuals in 2017.

Conclusion:

The age-standardized incidence or prevalence estimates in the Faroes seem to be lower than in other countries. The incidence was relatively stable in the period while the prevalence of dementia simultaneously increased.

Assessing the Prevalence of Undetected Possible Dementia in Faroese Nursing Homes

INTRODUCTION

To assess the prevalence of possible dementia among nursing home residents in the Faroe Islands.

METHOD

This cross-sectional study, undertaken in 2017, included all nursing homes in the Faroe Islands (n = 30), housing 591 residents. All residents were invited to participate, except those with an existing clinical diagnosis of dementia or living in dementia units (n = 207). A total of 232 residents participated, while 39 declined and 113 were unable to give consent, had died, or were not permanent residents at the time of examination. Cognitive screening was carried out using the Mini-Mental State Examination (MMSE) and the Informant Questionnaire on Cognitive Decline (IQCODE).

RESULTS

Possible dementia was found in 49% to 78% of the participants depending on the method used. According to both MMSE and IQCODE (AND rule), possible dementia was present in 105 participants (49%). According only to IQCODE, 119 participants (55%) scored above the cut-off (≥3.6), according to MMSE alone, 162 participants (72%) scored below the cut-off (≤24 on MMSE), while 175 participants (78%) screened positive according to either MMSE or IQCODE (OR rule). A rough estimate of the prevalence of possible dementia in the entire nursing home population (n = 591) including residents with known dementia and those with possible dementia from this study was between 61% and 73%.

CONCLUSION

A high percentage (49-78%) of the participating nursing home residents without a pre-dementia diagnosis were assessed to have possible dementia based on screening with standardized tools, indicating a high degree of dementia underdiagnoses in Faroese nursing homes. This high prevalence of dementia is of significance for the clinical practice, running, and planning of nursing homes and pinpoints a need to act upon this, not only in the Faroes but also worldwide.

Increased risk of sudden death in untreated primary carnitine deficiency

Primary carnitine deficiency (PCD) affects fatty acid oxidation and is associated with cardiomyopathy and cardiac arrhythmia, but the risk of sudden death in PCD is unknown. The Faroe Islands have a high prevalence of PCD, 1:300. This study systematically investigated a possible association between untreated PCD and sudden death in young Faroese subjects. We investigated all medico-legal cases of sudden death between 1979 and 2012 among subjects below the age of 45. Stored biomaterial was examined with molecular genetic analysis to reveal PCD. We compared the prevalence of PCD among sudden death cases with that of the background population (0.23%) to calculate the odds ratio (OR) for sudden death with PCD. Biomaterial was available and genetically analyzed from 53 of 65 sudden death cases (82%) in the Faroe Islands. Six (one male and five females) of the 53 cases were homozygous for the PCD related c.95A>G mutation-a prevalence of 11.3% (95% CI 5%-23%) and an OR of 54.3 (95% CI 21-138, P < .0001) for the association between sudden death and untreated PCD. Only 11 of the 53 sudden death cases were women-of whom five were homozygous for the c.95A>G mutation (45.5%) yielding an OR of 348.8 (95% CI 94-1287, P < .0001) for the association between sudden death and untreated PCD in females. This study showed a strong association between sudden death and untreated PCD, especially in females.

High Prevalence of Dystonia in the Faroe Islands: A Population-Based Study

BACKGROUND

There are fewer than 5 population-based studies of dystonia worldwide. Only one utilized a movement disorders neurologist. Given the potential for founder effects, and the highly genetic nature of dystonia, the Faroe Islands provide a particularly interesting setting to study the prevalence of dystonia.

OBJECTIVE

To estimate the prevalence of dystonia.

METHODS

We used a 2-phase, population-based design, screening 1,334 randomly selected Faroese individuals aged ≥40 years from which a subsample of 227 participated in an in-person clinical evaluation. Dystonia was assessed by 2 movement disorder neurologists using videotaped examinations.

RESULTS

Two of 227 (0.88%, 95% CI -0.33 to 2.09%) were diagnosed with cervical or segmental dystonia. An unusual form of thumb flexion dystonia was noted in 75 more, yielding a combined prevalence of 33.92% (95% CI 27.73-40.11%).

CONCLUSIONS

The prevalence of cervical or segmental dystonia was as high as in one prior population-based study using similar methods. Furthermore, an unusual form of thumb flexion dystonia was uncovered, which yielded an extraordinarily high prevalence of dystonia in this population. Although our methods likely contributed to more complete capture of subtle dystonia, founder effects are highly likely to have been an additional major contributor to these findings.

Involuntary Thumb Flexion on Neurological Examination: An Unusual Form of Upper Limb Dystonia in the Faroe Islands

Background

The prevalence of dystonia varies worldwide. A prior report suggested a high prevalence of focal dystonia in the Faroese population, possibly reflecting a founder effect. During standardized neurological examination as part of an ongoing neuroepidemiologic study in the Faroe Islands, we noted an unusual phenomenon of thumb flexion during repetitive hand movements in a subset of subjects and sought to define its phenomenology.

Methods

We requested commentary from a panel of dystonia experts regarding the phenomenology of the movements. These experts reviewed the videotaped neurological examination.

Results

Among the experts, dystonia was the leading diagnosis. Alternate causes were considered, but deemed less likely.

Discussion

Diagnosis of dystonia requires careful clinical assessment and consideration of associated features. We report a novel form of dystonia, not previously described to our knowledge, in this isolated population. Further studies of dystonia prevalence in the Faroe Islands are merited to characterize its burden in this population and its specific clinical characteristics.

Prevalence of Essential Tremor in the Faroe Islands: A Population-Based Study

BACKGROUND

No studies of the prevalence of one of the most common movement disorders, essential tremor (ET), have been undertaken in the Faroe Islands. Given the potential for founder effects in the Islands, and the highly genetic nature of ET, the Faroe Islands provide a particularly interesting setting in which to study the prevalence of ET.

OBJECTIVE

To estimate the prevalence of ET and study its characteristics.

METHODS

We used a 2-phase, population-based design, screening 1,328 randomly selected Faroese individuals aged ≥40 years. A subsample of 282 individuals who had returned the spirals and questionnaire was selected to participate in an in-person clinical evaluation. Tremor was systematically quantified by a senior movement disorder neurologist with particular specialization in tremor using a reliable and valid clinical rating scale followed by the application of rigorous diagnostic criteria used by tremor investigators internationally.

RESULTS

The overall crude prevalence was 2.9%. The age-adjusted prevalence was 3.1%. There was an age-associated rise in prevalence; by age ≥70, prevalence reached 4.8%. Twenty six of 27 (96.2%) were previously undiagnosed.

CONCLUSIONS

This is the first population-based study of the prevalence of ET in the Faroe Islands. The estimated prevalence was similar to studies using the same or comparable methodologies.

Prevalence of type 2 diabetes and prediabetes in the Faroe Islands

AIMS

To determine the prevalence of type 2 diabetes mellitus and prediabetes among the population aged 40-74 years in the Faroe Islands.

METHODS

This population-based cross-sectional survey, conducted between 2011 and 2012, invited 2186 randomly selected individuals (corresponding to 11.1% of the entire population aged 40-74 years). Subjects were screened using finger capillary blood for glycosylated hemoglobin, type A1c, non-fasting random plasma glucose, fasting plasma glucose followed by oral glucose tolerance test. The test was based on an algorithm that accounts for screening, diagnostic and confirmatory steps. Anthropometric measures and a questionnaire including medical history, medication, hereditary conditions, and food intake were included.

RESULTS

The study included 1772 participants. Of the 1772, 169 (9.5%) had type 2 diabetes mellitus (3.0% of which were diagnosed upon study inclusion), thus 31.4% of subjects with diabetes were undiagnosed at the time of examination. A total of 271 (15.3%) had prediabetes. Diabetes was more prevalent among men, significantly from age ≥60 years. Women had lower mean fasting plasma glucose concentrations and men had lower values for 2-h plasma glucose. Predictors associated with diabetes mellitus included obesity (BMI ≥ 30), abnormal waist/hip ratio, history of hypertension or cardiovascular attack and family history of diabetes mellitus and leisure activity.

CONCLUSIONS

The prevalences of diabetes and prediabetes increased with age and were more frequent among men. The detected prevalence in the Faroe Islands was slightly higher than other Nordic countries.

Association between genes on chromosome 19p13.2 and panic disorder

Panic disorder (PD) is a severe and disabling mental disorder, which is moderately heritable. In a previous study, we carried out a genome-wide association study using patients with PD and control individuals from the isolated population of the Faroe Islands and identified chromosome 19p13.2 as a candidate region. To further investigate this chromosomal region for association with PD, we analysed eight single nucleotide polymorphisms (SNPs) in three candidate genes - small-nuclear RNA activating complex, polypeptide 2 (SNAPC2), mitogen-activated protein kinase kinase 7 (MAP2K7) and leucine-rich repeat containing 8 family, member E (LRRC8E) - these genes have previously been directly or indirectly implicated in other mental disorders. A total of 511 patients with PD and 1029 healthy control individuals from the Faroe Islands, Denmark and Germany were included in the current study. SNPs covering the gene region of SNAPC2, MAP2K7 and LRRC8E were genotyped and tested for association with PD. In the Faroese cohort, rs7788 within SNAPC2 was significantly associated with PD, whereas rs3745383 within LRRC8E was nominally associated. No association was observed between the analysed SNPs and PD in the Danish cohorts. In the German women, we observed a nominal association between rs4804833 within MAP2K7 and PD. We present further evidence that chromosome 19p13.2 may harbour candidate genes that contribute towards the risk of developing PD. Moreover, the implication of the associated genes in other mental disorders may indicate shared genetic susceptibility between mental disorders. We show that associated variants may be sex specific, indicating the importance of carrying out a sex-specific association analysis of PD.

Inflammatory bowel diseases in Faroese-born Danish residents and their offspring: further evidence of the dominant role of environmental factors in IBD development

BACKGROUND

The incidence of inflammatory bowel disease (IBD) is record high in the Faroe Islands, and many Faroese emigrate to Denmark, where the IBD incidence is considerably lower.

AIM

To study the IBD incidence in first-, second- and third-generation immigrants from the Faroe Islands to Denmark to assess the extent to which the immigrants adopt the lower IBD incidence of their new home country.

METHODS

Data on Faroese-born Danish residents and their children were retrieved from the Danish Central Population Register for 1980-2014. Incident IBD cases were identified from the Danish National Patient Register. Standardised Incidence Ratios (SIRs) were used to compare the IBD risk in immigrants with that of Danes. 95% confidence intervals (CI) were calculated using the square-root transform.

RESULTS

First-generation Faroese immigrants had a higher IBD incidence than Danes, SIR 1.25 (95% CI, 0.97-1.59) for men and 1.28 (95% CI, 1.05-1.53) for women. This excess risk derived from ulcerative colitis (UC), SIR 1.44 (95% CI, 1.10-1.87) for men and 1.36 (95% CI, 1.09-1.68) for women. No excess risk was found for Crohn's disease (CD). The UC risk was nearly doubled during the immigrants' first 10 years in Denmark; SIR 2.13 (95% CI, 1.52-2.92) for men and 1.63 (95% CI, 1.19-2.18) for women.

CONCLUSIONS

Although some impact of genetic dilution cannot be excluded, our findings indicate importance of gene-environment interplay in UC, as the excess UC risk in Faroese immigrants to Denmark disappeared over time and over one generation in men and over two generations in women.

Whole-exome sequencing of individuals from an isolated population implicates rare risk variants in bipolar disorder

Bipolar disorder affects about 1% of the world's population, and its estimated heritability is about 75%. Only few whole genome or whole-exome sequencing studies in bipolar disorder have been reported, and no rare coding variants have yet been robustly identified. The use of isolated populations might help finding variants with a recent origin, more likely to have drifted to higher frequency by chance. Following this approach, we investigated 28 bipolar cases and 214 controls from the Faroe Islands by whole exome sequencing, and the results were followed-up in a British sample of 2025 cases and 1358 controls. Seventeen variants in 16 genes in the single-variant analysis, and 3 genes in the gene-based statistics surpassed exome-wide significance in the discovery phase. The discovery findings were supported by enrichment analysis of common variants from genome-wide association studies (GWAS) data and interrogation of protein-protein interaction networks. The replication in the British sample confirmed the association with NOS1 (missense variant rs79487279) and NCL (gene-based test). A number of variants from the discovery set were not present in the replication sample, including a novel PITPNM2 missense variant, which is located in a highly significant schizophrenia GWAS locus. Likewise, PIK3C2A identified in the gene-based analysis is located in a combined bipolar and schizophrenia GWAS locus. Our results show support both for existing findings in the literature, as well as for new risk genes, and identify rare variants that might provide additional information on the underlying biology of bipolar disorder.

Primary Carnitine Deficiency: Is Foetal Development Affected and Can Newborn Screening Be Improved?

Primary carnitine deficiency (PCD) causes low levels of carnitine in patients potentially leading to metabolic and cardiac symptoms. Newborn screening for PCD is now routine in many countries by measuring carnitine levels in infants. In this study we report Apgar scores, length and weight in newborns with PCD and newborns born to mothers with PCD compared to controls. Furthermore we report how effective different screening algorithms have been to detect newborns with PCD in the Faroe Islands.

RESULTS

Newborns with PCD and newborns born to mothers with PCD did not differ with regard to Apgar scores, length and weight compared to controls. Newborns with PCD and newborns born to mothers with PCD had significantly lower levels of free carnitine (fC0) than controls. Screening algorithms focusing only on fC0 had a high rate of detection of newborns with PCD. Sample collection 4-9 days after birth seems to result in a higher detection rate than the current 2-3 days.

CONCLUSION

The clinical status at birth in infants with PCD and infants born to mothers with PCD does not differ compared to control infants. Screening algorithms for PCD should focus on fC0, and blood samples should be taken when the maternal influence on fC0 has diminished.

The Faroese IBD Study: Incidence of Inflammatory Bowel Diseases Across 54 Years of Population-based Data

BACKGROUND AND AIMS

Inflammatory bowel diseases [IBDs] include Crohn's disease [CD], ulcerative colitis [UC], and IBD unclassified [IBDU]. In 2010 and 2011, the ECCO-EpiCom study found the worldwide highest incidence of inflammatory bowel disease [IBD] in the Faroe Islands: 83 per 100 000 [European Standard Population, ESP]. The present study assessed the long-term time trends in IBD incidence in the Faroese population.

METHODS

In this population-based study, data were retrieved from the National Hospital of the Faroe Islands and included all incident cases of CD, UC, and IBDU diagnosed between July 1960 and July 2014. Patients of all ages were included and diagnoses were defined according to the Copenhagen Diagnostic Criteria.

RESULTS

A total of 664 incident IBD patients were diagnosed: 113 with CD, 417 with UC, and 134 with IBDU. Of these, 51 [8%] were diagnosed with paediatric-onset IBD. Between 1960 and 1979, a total of 55 persons were diagnosed; 105 in 1980-89; 166 in 1990-99; 180 in 2000-09; and 158 in 2010-14. This represented an increase in the age-standardised IBD incidence rate from 7, 25, 40, and 42 to 74 per 100 000 [ESP]. For CD, the increase was from 1 to 10, for UC from 4 to 44, and for IBDU from 2 to 21 per 100 000 [ESP].

CONCLUSIONS

The high IBD incidence was found to be a relatively new phenomenon. The observed increase is unlikely to be an artefact resulting from, for instance, better registration. Our study indicated a real and increasing disease burden resulting from changing-so far unidentified-exposures.

High prevalence of primary focal dystonia in the Faroe Islands

OBJECTIVE

There are no previous studies undertaken about primary focal dystonia in the Faroe Islands. The aim of this study was to establish the prevalence of these diseases in the Faroese population.

METHODS

Patients were ascertained and registered prospectively from January 1, 1994, through 2013 when they were examined at the Neurological Clinic of the Faroese National Hospital or at a private neurological practice, which together constitutes all the available neurological services in the Faroe Islands.

RESULT

On January 1, 2014, there were 29 individuals within the entire Faroese population of 48,100 with primary focal dystonia: 23 with torticollis, four with writer's cramp, one with oromandibular dystonia, and one with laryngeal dystonia; no one had blepharospasm. The prevalence of primary focal dystonia was 602 per million (395-873) (95% confidence limit). The most common subtype was cervical dystonia with a prevalence of 478 (332-728) per million.

CONCLUSION

The study yielded that (i) the prevalence of primary focal dystonia of 602 (395-873) per million is far higher in the Faroe Islands than that revealed in most other regions studied and (ii) the prevalence of the cervical dystonia subtype is far more common than elsewhere with the highest prevalence of 478 (332-728), which is higher than described in any previously published survey. As the study is serviced-based, the result may underestimate actual occurrence; thus, prevalence rates may be even higher.

Genetic analysis of the isolated Faroe Islands reveals SORCS3 as a potential multiple sclerosis risk gene

Background:

In search of the missing heritability in multiple sclerosis (MS), additional approaches adding to the genetic discoveries of large genome-wide association studies are warranted.

Objective:

The objective of this research paper is to search for rare genetic MS risk variants in the genetically homogenous population of the isolated Faroe Islands.

Methods:

Twenty-nine Faroese MS cases and 28 controls were genotyped with the HumanOmniExpressExome-chip. The individuals make up 1596 pair-combinations in which we searched for identical-by-descent shared segments using the PLINK-program.

Results:

A segment spanning 63 SNPs with excess case-case-pair sharing was identified (0.00173 < p > 0.00212). A haplotype consisting of 42 of the 63 identified SNPs which spanned the entire the Sortilin-related vacuolar protein sorting 10 domain containing receptor 3 ( SORCS3) gene had a carrier frequency of 0.34 in cases but was not present in any controls ( p = 0.0008).

Conclusion:

This study revealed an oversharing in case-case-pairs of a segment spanning 63 SNPs and the entire SORCS3. While not previously associated with MS, SORCS3 appears to be important in neuronal plasticity through its binding of neurotrophin factors and involvement in glutamate homeostasis. Although additional work is needed to scrutinise the genetic effect of the SORCS3-covering haplotype, this study suggests that SORCS3 may also be important in MS pathogenesis.

Pharmacogenetics of drug oxidation via cytochrome P450 (CYP) in the populations of Denmark, Faroe Islands and Greenland

Denmark, the Faroe Islands and Greenland are three population-wise small countries on the northern part of the Northern Hemisphere, and studies carried out here on the genetic control over drug metabolism via cytochrome P450 have led to several important discoveries. Thus, CYP2D6 catalyzes the 2-hydroxylation, and CYP2C19 in part catalyzes the N-demethylation of imipramine. The phenomenon of phenocopy with regard to CYP2D6 was first described when Danish patients changed phenotype from extensive to poor metabolizers during treatment with quinidine. It was a Danish extensive metabolizer patient that became a poor metabolizer during paroxetine treatment, and this was due to the potent inhibition of CYP2D6 by paroxetine, which is also is metabolized by this enzyme. Fluoxetine and norfluoxetine are also potent inhibitors of CYP2D6, and fluvoxamine is a potent inhibitor of both CYP1A2 and CYP2C19. The bioactivation of proguanil to cycloguanil is impaired in CYP2C19 poor metabolizers. The O-demethylation of codeine and tramadol to their respective my-opioid active metabolites, morphine and (+)-O-desmethyltramadol was markedly impaired in CYP2D6 poor metabolizers compared to extensive metabolizers, and this impairs the hypoalgesic effect of the two drugs in the poor metabolizers. The frequency of CYP2D6 poor metabolizers is 2%-3% in Greenlanders and nearly 15% in the Faroese population. The frequency of CYP2C19 poor metabolizers in East Greenlanders is approximately 10%. A study in Danish mono and dizygotic twins showed that the non-polymorphic 3-N-demethylation of caffeine catalyzed by CYP1A2 is subject to approximately 70% genetic control.

Mitochondrial DNA variation in the Viking age population of Norway

The medieval Norsemen or Vikings had an important biological and cultural impact on many parts of Europe through raids, colonization and trade, from about AD 793 to 1066. To help understand the genetic affinities of the ancient Norsemen, and their genetic contribution to the gene pool of other Europeans, we analysed DNA markers in Late Iron Age skeletal remains from Norway. DNA was extracted from 80 individuals, and mitochondrial DNA polymorphisms were detected by next-generation sequencing. The sequences of 45 ancient Norwegians were verified as genuine through the identification of damage patterns characteristic of ancient DNA. The ancient Norwegians were genetically similar to previously analysed ancient Icelanders, and to present-day Shetland and Orkney Islanders, Norwegians, Swedes, Scots, English, German and French. The Viking Age population had higher frequencies of K*, U*, V* and I* haplogroups than their modern counterparts, but a lower proportion of T* and H* haplogroups. Three individuals carried haplotypes that are rare in Norway today (U5b1b1, Hg A* and an uncommon variant of H*). Our combined analyses indicate that Norse women were important agents in the overseas expansion and settlement of the Vikings, and that women from the Orkneys and Western Isles contributed to the colonization of Iceland.

High inbreeding in the Faroe Islands does not appear to constitute a risk factor for multiple sclerosis

Background:

Large population-based genome-wide association studies have identified several multiple sclerosis (MS) genetic risk variants, but the existing missing heritability warrants different strategies. Isolated populations offer an alternative way of searching for rare genetic variants and evaluating the possible role of consanguinity in the development of MS. Studies of consanguinity and MS risk have yielded conflicting results.

Objectives:

In this study we investigated the role of consanguinity on MS risk in the relatively isolated Faroe Islands, which have a presumed high level of inbreeding.

Methods:

A total of 29 cases and 28 matched controls were genotyped and assessed for inbreeding coefficients, number of runs of homozygosity (ROH) at different lengths and observed number of homozygotes as measures of relatedness. Parametric and non-parametric statistical models were applied.

Results:

Both cases and controls exhibited considerable relatedness demonstrated by very high inbreeding coefficients, large number of observed homozygotes and many long ROH. However, apart from the number of ROH ≥ 2.5 mega base pairs, no significant differences between the two groups were observed.

Conclusions:

Overall, no significant difference between cases and controls were found, indicating that consanguinity in itself does not appear to be an important risk factor for MS in the population of the Faroe Islands.

Myasthenia gravis incidence in a general North Atlantic isolated population

OBJECTIVE

There are no previous studies undertaken about myasthenia gravis in the Faroe Islands. The aim of this study was to establish the incidence of onset of this disease in the Faroese population.

METHOD

Patients were ascertained and registered prospectively from 1986 to 2013 when they were examined at the Neurological Clinic of the Faroese National Hospital or at a private neurological practice, which constitutes all the available neurological services in the Faroe Islands.

RESULT

Twelve new diagnoses were made over a 27-year period, providing an incidence density rate of 9.4 per million person-years (95% confidence limit 4.9-16.5). At presentation, nine of 12 patients had generalized myasthenia gravis and two patients had pure ocular disease, and in one patient, the symptoms were restricted to the bulbo-facial muscles. The sex ratio was 2:1, F/M. In nine of the cases, a positive result of acetylcholine receptor antibody assay was documented. In all patients, there was a beneficial response to anticholinesterase administration.

CONCLUSION

The result yielded no strong evidence of a difference in incidence between that found in the Faroe Islands and those in most European studies, apart from recent studies from London, UK; Norway; Spain, and Italy in which incidences from 21 to 30 per million person-years had been reported.

East-West gradient in the incidence of inflammatory bowel disease in Europe: the ECCO-EpiCom inception cohort

OBJECTIVE

The incidence of inflammatory bowel disease (IBD) is increasing in Eastern Europe. The reasons for these changes remain unknown. The aim of this study was to investigate whether an East-West gradient in the incidence of IBD in Europe exists.

DESIGN

A prospective, uniformly diagnosed, population based inception cohort of IBD patients in 31 centres from 14 Western and eight Eastern European countries covering a total background population of approximately 10.1 million people was created. One-third of the centres had previous experience with inception cohorts. Patients were entered into a low cost, web based epidemiological database, making participation possible regardless of socioeconomic status and prior experience.

RESULTS

1515 patients aged 15 years or older were included, of whom 535 (35%) were diagnosed with Crohn's disease (CD), 813 (54%) with ulcerative colitis (UC) and 167 (11%) with IBD unclassified (IBDU). The overall incidence rate ratios in all Western European centres were 1.9 (95% CI 1.5 to 2.4) for CD and 2.1 (95% CI 1.8 to 2.6) for UC compared with Eastern European centres. The median crude annual incidence rates per 100,000 in 2010 for CD were 6.5 (range 0-10.7) in Western European centres and 3.1 (range 0.4-11.5) in Eastern European centres, for UC 10.8 (range 2.9-31.5) and 4.1 (range 2.4-10.3), respectively, and for IBDU 1.9 (range 0-39.4) and 0 (range 0-1.2), respectively. In Western Europe, 92% of CD, 78% of UC and 74% of IBDU patients had a colonoscopy performed as the diagnostic procedure compared with 90%, 100% and 96%, respectively, in Eastern Europe. 8% of CD and 1% of UC patients in both regions underwent surgery within the first 3 months of the onset of disease. 7% of CD patients and 3% of UC patients from Western Europe received biological treatment as rescue therapy. Of all European CD patients, 20% received only 5-aminosalicylates as induction therapy.

CONCLUSIONS

An East-West gradient in IBD incidence exists in Europe. Among this inception cohort--including indolent and aggressive cases--international guidelines for diagnosis and initial treatment are not being followed uniformly by physicians.

Carnitine levels in 26,462 individuals from the nationwide screening program for primary carnitine deficiency in the Faroe Islands

BACKGROUND

Primary carnitine deficiency (PCD) is an autosomal recessive disorder of fatty acid oxidation and has been associated to episodes of sudden death in the Faroe Islands. Data are presented from the nationwide population based Faroese screening program to find people with low carnitine levels indicating PCD.

METHODS

Whole blood samples from dried blood spots were analysed by tandem mass spectrometry with and without butylation. Genetic analyses were performed in all people with non-butylated free carnitine (fC0) below 7 μmol/L.

RESULTS

55 % (n = 26,462) of the entire population was screened and 89 PCD patients were identified, yielding an overall prevalence of 1:297 of PCD in the Faroe Islands. Carnitine levels were positively correlated to age in both males and females (p < 0.003) although levels decreased in females when reaching fertile age. The gender difference in mean carnitine levels was significant during female fertile age (4.71 μmol/L fC0 in the age group 25-30 years, p < 0.01). A lower cut-off of 5 μmol/L in fC0 identified all homozygous for the severe genotype c.95A > G (p.N32S) (n = 20).

CONCLUSION

Carnitine levels differ by gender and age. A lower cut-off of 5 μmol/L in fC0 was appropriate to identify c.95A > G homozygotes. The prevalence of PCD in the Faroe Islands is the highest reported in the world (1:297).

Genetic tracking of mice and other bioproxies to infer human history

The long-distance movements made by humans through history are quickly erased by time but can be reconstructed by studying the genetic make-up of organisms that travelled with them. The phylogeography of the western house mouse (Mus musculus domesticus), whose current widespread distribution around the world has been caused directly by the movements of (primarily) European people, has proved particularly informative in a series of recent studies. The geographic distributions of genetic lineages in this commensal have been linked to the Iron Age movements within the Mediterranean region and Western Europe, the extensive maritime activities of the Vikings in the 9th to 11th centuries, and the colonisation of distant landmasses and islands by the Western European nations starting in the 15th century. We review here recent insights into human history based on phylogeographic studies of mice and other species that have travelled with humans, and discuss how emerging genomic methodologies will increase the precision of these inferences.

Incidence of amyotrophic lateral sclerosis in the Faroe Islands

OBJECTIVES

The establishment of variations in the incidence of amyotrophic lateral sclerosis (ALS) in the Faroese population from that found in other general populations may point to risk factors for the development of this disease among the Faroese. The aim of this study was to estimate the annual incidence of ALS during the period 1987-2009 and to compare the occurrence of ALS in the Faroe Islands with data from three European countries.

METHOD

All Faroese patients diagnosed with ALS in this period are documented in the current longitudinal prospective study.

RESULTS

The incidence of ALS in the Faroe Islands during the period 1987-2009 is 2.6 (1.7-3.7) per 100,000 annually. The results yielded no strong evidence of a difference (P = 0.09) in the incidence of ALS between Faroe Islands and Europe. The sample population is small, and this, of course, impacts the statistical precision of the findings.

CONCLUSION

The data clearly suggest, however, that the Faroese population is probably not subject to an increased risk of ALS, even though certain risk factors are present in the general population: (i) a fish-based diet contaminated with mercury and polychlorinated biphenyl; (ii) the high occurrence of the recessive carnitine transporter genetic defect; and (iii) the anticipated high degree of inbreeding at the fifth generation.

A genome-wide study of panic disorder suggests the amiloride-sensitive cation channel 1 as a candidate gene

Panic disorder (PD) is a mental disorder with recurrent panic attacks that occur spontaneously and are not associated to any particular object or situation. There is no consensus on what causes PD. However, it is recognized that PD is influenced by environmental factors, as well as genetic factors. Despite a significant hereditary component, genetic studies have only been modestly successful in identifying genes of importance for the development of PD. In this study, we conducted a genome-wide scan using microsatellite markers and PD patients and control individuals from the isolated population of the Faroe Islands. Subsequently, we conducted a fine mapping, which revealed the amiloride-sensitive cation channel 1 (ACCN1) located on chromosome 17q11.2-q12 as a potential candidate gene for PD. The further analyses of the ACCN1 gene using single-nucleotide polymorphisms (SNPs) revealed significant association with PD in an extended Faroese case-control sample. However, analyses of a larger independent Danish case-control sample yielded no substantial significant association. This suggests that the possible risk alleles associated in the isolated population are not those involved in the development of PD in a larger outbred population.

Migration of Antarctic minke whales to the Arctic

The Antarctic minke whale (Balaenoptera bonaerensis), and the common minke whale found in the North Atlantic (Balaenoptera acutorostrata acutorostrata), undertake synchronized seasonal migrations to feeding areas at their respective poles during spring, and to the tropics in the autumn where they overwinter. Differences in the timing of seasons between hemispheres prevent these species from mixing. Here, based upon analysis of mitochondrial and microsatellite DNA profiles, we report the observation of a single B. bonaerensis in 1996, and a hybrid with maternal contribution from B. bonaerensis in 2007, in the Arctic Northeast Atlantic. Paternal contribution was not conclusively resolved. This is the first documentation of B. bonaerensis north of the tropics, and, the first documentation of hybridization between minke whale species.

Multiple sclerosis: variation of incidence of onset over time in the Faroe Islands

Epidemiological studies of multiple sclerosis (MS) conducted in the Faroe Islands identified 10 annual incidences per 100,000 in 1945 and 4.5 in the period 1986-2007. The aim of this study was to estimate the annual incidence of onset of MS in the Faroe Islands in the six decades from 1943 to 2002 and during the period 2003-7.All patients diagnosed with MS between 1943 and 2007 were documented. The incidence of MS before 1943 was around 0.2 per 100,000 annually. During the period 1943-62, an annual incidence rate of 4.4 [confidence interval (CI) 2.9-6.1] per 100,000 was observed. During the 20-year period 1963-82, the level declined significantly (p < 0.001) to around 0.6 (0.3-1.5). Thereafter, an increase was seen during the period 1983-2002, evidencing a significant (p < 0.001) sevenfold increase in the annual incidence to 4.6 (3.2-6.2) per 100,000. Subsequently, for the period 2003-7, there was again a decline to 2.4 (2.1-3.3) (p = 0.003). This study confirms that significant variation in the incidence of MS has occurred in the Faroes over time. Because the rate of genetic change within the Faroese population is relatively slow, the study suggests environmental factors as a contributing cause of MS. If only genetic factors for susceptibility were important, the incidence rate should not wax and wane over time, as is observed.

Multiple sclerosis incidence in the Faroe Islands 1986-2007

OBJECTIVE

Epidemiological studies of the isolated Faroese population in 1945 identified a high annual incidence of multiple sclerosis (MS) of 10/100,000. At the time, there was speculation that the disease was brought to the country by British occupation forces resident in the islands from 1940 to 1945. The objective of the current study is to determine the incidence of diagnosis of MS in the Faroe Islands during the period 1986-2007.

METHODS

All patients in the Faroe Islands diagnosed with MS from July 1, 1986 to July 1, 2007 are documented in the current longitudinal, prospective study. The diagnosis is based on clinical observation, magnetic resonance imaging scanning, cerebrospinal fluid tests, and visual evoked potential response testing.

RESULTS

The incidence of MS during the period 1986-2007 is 4.5/100,000 annually. This is generally of the same order of magnitude as other research findings in Scandinavia and Iceland. The incidence of MS from 1986 to 2007 is about double the incidence in the Faroe Islands for the period from 1940 to 1986, calculated to be 2.7/100,000 annually.

CONCLUSION

The observed incidence of MS in the Faroe Islands, where the population is genetically homogeneous and where the diet exposes the population to neuro-toxic contamination, is at the same level as found in other high-risk regions. The former detected epidemics of MS in Faroe Islands seems apparently to have leveled out and could not be recognized in the recent period covered by the present survey.

A comparison of SNP and STR loci for delineating population structure and performing individual genetic assignment

Background

Technological advances have lead to the rapid increase in availability of single nucleotide polymorphisms (SNPs) in a range of organisms, and there is a general optimism that SNPs will become the marker of choice for a range of evolutionary applications. Here, comparisons between 300 polymorphic SNPs and 14 short tandem repeats (STRs) were conducted on a data set consisting of approximately 500 Atlantic salmon arranged in 10 samples/populations.

Results

Global F_ST ranged from 0.033-0.115 and -0.002-0.316 for the 14 STR and 300 SNP loci respectively. Global F_ST was similar among 28 linkage groups when averaging data from mapped SNPs. With the exception of selecting a panel of SNPs taking the locus displaying the highest global F_ST for each of the 28 linkage groups, which inflated estimation of genetic differentiation among the samples, inferred genetic relationships were highly similar between SNP and STR data sets and variants thereof. The best 15 SNPs (30 alleles) gave a similar level of self-assignment to the best 4 STR loci (83 alleles), however, addition of further STR loci did not lead to a notable increase assignment whereas addition of up to 100 SNP loci increased assignment.

Conclusion

Whilst the optimal combinations of SNPs identified in this study are linked to the samples from which they were selected, this study demonstrates that identification of highly informative SNP loci from larger panels will provide researchers with a powerful approach to delineate genetic relationships at the individual and population levels.

Core features of suicide. Gender, age, alcohol and other putative risk factors in a low-incidence population

The aim of the study was to elucidate some supposed core features of suicide through a study of suicide in a low-incidence population. The material covered all suicides and undetermined deaths 1945-2004 in the Faroe Islands (a low-incidence population) and the study made use of all available information. Results showed that suicide rate had been low since the Second World War. However, there was an increase throughout the 1970s and 1980s. Supposed core features of suicide, such as gender, marital status, former psychiatric admittance, former suicidal behaviour, alcohol and method preference were confirmed. Others were not, such as an increasing rate with old age. In diagnostics, the role of psychiatric disorders was confirmed, but so was a substantial role of "no disorder". Increase period revealed a high proportion of cases with alcohol involved and a substantial part included males, in age groups 25-64 years, unmarried, divorced and alcohol intoxicated. The main conclusion was that a low-incidence population of suicide population confirmed some supposed core features of the suicide phenomenon. Others, related to age and psychiatric disorders, were only partially confirmed. In periods of increase, the most vulnerable were the young and middle-aged males, unmarried, divorced, and alcohol played a crucial role.

Studies in 3,523 Norwegians and meta-analysis in 11,571 subjects indicate that variants in the hepatocyte nuclear factor 4 alpha (HNF4A) P2 region are associated with type 2 diabetes in Scandinavians

OBJECTIVE

Recent publications have found an association between common variants near the hepatocyte nuclear factor 4 alpha (HNF4A) P2 promoter and type 2 diabetes in some populations but not in others, and the role for HNF4A in type 2 diabetes has remained unclear. In an attempt to address these inconsistencies, we investigated HNF4A single nucleotide polymorphisms (SNPs) in a large population-based sample and included a meta-analysis of published studies.

RESEARCH DESIGN AND METHODS

We genotyped 12 SNPs in the HNF4A region in a Norwegian population-based sample of 1,644 individuals with type 2 diabetes and 1,879 control subjects (the Nord-Trøndelag Health Study [HUNT] 2). We combined our data with all previously published case/control studies and performed a meta-analysis.

RESULTS

Consistent with initial studies, we found a trend toward association for the SNPs rs1884613 (odds ratio [OR] 1.17 [95% CI 1.03-1.35]) and rs2144908 (1.21 [1.05-1.38]) in the P2 region and for rs4812831 (1.21 [1.02-1.44]), located 34 kb downstream of the P2 promoter. Meta-analysis, comprising 12,292 type 2 diabetic case and 15,519 control subjects, revealed a nonsignificant OR of 1.05 (95% CI 0.98-1.12) but with significant heterogeneity between the populations. We therefore performed a subanalysis including only the data for subjects from Scandinavia. Among the 4,000 case and 7,571 control Scandinavian subjects, a pooled OR of 1.14 (1.06-1.23), P = 0.0004, was found for the SNP rs1884613.

CONCLUSIONS

Our results suggest that variation in the HNF4A region is associated with type 2 diabetes in Scandinavians, highlighting the importance of exploring small genetic effects in large, homogenous populations.

Was the C282Y mutation an Irish Gaelic mutation that the Vikings help disseminate?

The C282Y mutation is held to have arisen in either a Celtic or a Viking ancestor some 60 generations ago. While the Scandinavians have a high frequency of C282Y, the Irish have the highest frequency of the C282Y mutation in the world. However testing of the Irish people for C282Y has been patchy. The true frequency of the C282Y mutation in Ireland and specifically in the relatively isolated western province of Connaught is unknown. Establishment of the C282Y frequency in the Irish male population of Connaught with traditional Irish surnames, a group which has a virtual fixation for Y chromosome R1b3, could help establish C282Y as an Irish mutation. Elucidation of greater C282Y haplotype diversity for the Irish as opposed to the Scandinavians would indicate the Irish as the likely source population for C282Y. Taken together, linking of C282Y to the Irish Gaelic male population of Connaught and establishment of an Irish origin of the C282Y mutation would point to dissemination of the C282Y mutation by Viking raiders and colonizers.