Population genomics of Mesolithic Scandinavia: Investigating early postglacial migration routes and high-latitude adaptation

Scandinavia was one of the last geographic areas in Europe to become habitable for humans after the Last Glacial Maximum (LGM). However, the routes and genetic composition of these postglacial migrants remain unclear. We sequenced the genomes, up to 57× coverage, of seven hunter-gatherers excavated across Scandinavia and dated from 9,500–6,000 years before present (BP). Surprisingly, among the Scandinavian Mesolithic individuals, the genetic data display an east–west genetic gradient that opposes the pattern seen in other parts of Mesolithic Europe. Our results suggest two different early postglacial migrations into Scandinavia: initially from the south, and later, from the northeast. The latter followed the ice-free Norwegian north Atlantic coast, along which novel and advanced pressure-blade stone-tool techniques may have spread. These two groups met and mixed in Scandinavia, creating a genetically diverse population, which shows patterns of genetic adaptation to high latitude environments. These potential adaptations include high frequencies of low pigmentation variants and a gene region associated with physical performance, which shows strong continuity into modern-day northern Europeans.

The Scandinavian peninsula was the last part of Europe to be colonized after the Last Glacial Maximum. The migration routes, cultural networks, and the genetic makeup of the first Scandinavians remain elusive and several hypotheses exist based on archaeology, climate modeling, and genetics. By analyzing the genomes of early Scandinavian hunter-gatherers, we show that their migrations followed two routes: one from the south and another from the northeast along the ice-free Norwegian Atlantic coast. These groups met and mixed in Scandinavia, creating a population more diverse than contemporaneous central and western European hunter-gatherers. As northern Europe is associated with cold and low light conditions, we investigated genomic patterns of adaptation to these conditions and genes known to be involved in skin pigmentation. We demonstrate that Mesolithic Scandinavians had higher levels of light pigmentation variants compared to the respective source populations of the migrations, suggesting adaptation to low light levels and a surprising signal of genetic continuity in TMEM131, a gene that may be involved in long-term adaptation to the cold.

Cattle Management for Dairying in Scandinavia's Earliest Neolithic

New evidence for cattle husbandry practices during the earliest period of the southern Scandinavian Neolithic indicates multiple birth seasons and dairying from its start. Sequential sampling of tooth enamel carbonate carbon and oxygen isotope ratio analyses and strontium isotopic provenancing indicate more than one season of birth in locally reared cattle at the earliest Neolithic Funnel Beaker (EN I TRB, 3950-3500 cal. B.C.) site of Almhov in Scania, Sweden. The main purpose for which cattle are manipulated to give birth in more than one season is to prolong lactation for the production of milk and dairy-based products. As this is a difficult, intensive, and time-consuming strategy, these data demonstrate complex farming practices by early Neolithic farmers. This result offers strong support for immigration-based explanations of agricultural origins in southern Scandinavia on the grounds that such a specialised skill set cannot represent the piecemeal incorporation of agricultural techniques into an existing hunter-gatherer-fisher economy.

Use of hormonal contraceptives among immigrant and native women in Norway: data from the Norwegian Prescription Database

OBJECTIVE

To examine the use of hormonal contraceptives among immigrant and native women in Norway.

DESIGN

Nationwide registry-based study based on merged data from the Norwegian Prescription Database, the Norwegian Population Registry, the Regular General Practitioner Database and the Medical Birth Registry.

SETTING

Norway.

SAMPLE

All women born abroad to two foreign-born parents (immigrants), or born in Norway to two Norwegian-born parents (natives) aged 16-45 years, who lived in Norway in 2008.

METHODS

Data on all collected supplies of hormonal contraceptives in 2008 were merged with demographic, socio-economic and immigration data, information on any delivery and women's general practitioners.

MAIN OUTCOME MEASURES

User rates of hormonal contraception and predictors of contraceptive use.

RESULTS

A total of 893,073 women were included, of whom 130,080 were immigrants. More native women (38%) used hormonal contraceptives compared with all immigrant groups (15-24%). The odds ratios for any use of hormonal contraceptives for immigrants compared with Norwegian-born women were; Nordic countries 0.53, South and Central America 0.53, Western countries 0.39, Asia 0.30, Eastern Europe 0.29, Africa 0.29. Work, education, long stay in Norway and young age of immigration predicted the use of hormonal contraceptives among immigrants.

CONCLUSIONS

The use of hormonal contraceptives varies between natives and immigrant groups. Further work is needed to ascertain whether these differences can be explained by higher desires for fertility, preferential use of non-hormonal contraceptives or other reasons identified through qualitative research.

"Pur sarripu pursa trutin": monster-fighting and medicine in early medieval Scandinavia

This paper seeks evidence among our extensive Scandinavian mythological texts for an area which they seldom discuss explicitly: the conceptualisation and handling of illness and healing. Its core evidence is two runic texts (the Canterbury Rune-Charm and the Sigtuna Amulet) which conceptualise illness as a "purs" ("ogre, monster"). The article discusses the semantics of "purs," arguing that illness and supernatural beings could be conceptualised as identical in medieval Scandinavia. This provides a basis for arguing that myths in which gods and heroes fight monsters provided a paradigm for the struggle with illness.

Moral transgression and illness in the Early Modern North

This article seeks to understand how people in the early modern age interpreted the nature of illness and the role that morality played in these interpretations. From this point of view illnesses were not only psycho-physical states or subjects for medical diagnosis but they were also subjects for narratives or stories through which people tried to understand what had caused their illness, and why it was happening to them. Illnesses were understood as strictly connected with the patient's character and were regarded as possible consequences of his personality. On the other hand, the interpretations also emphasised the ambivalence of a healer. Personal experiences and an understanding of one's life situation intertwined in these stories.

Estimation of the real population and its impact on the utilisation of healthcare services in Mediterranean resort regions: an ecological study

Background

The demographic structure has a significant influence on the use of healthcare services, as does the size of the population denominators. Very few studies have been published on methods for estimating the real population such as tourist resorts. The lack of information about these problems means there is a corresponding lack of information about the behaviour of populational denominators (the floating population or tourist load) and the effect of this on the use of healthcare services. The objectives of the study were: a) To determine the Municipal Solid Waste (MSW) ratio, per person per day, among populations of known size; b) to estimate, by means of this ratio, the real population in an area where tourist numbers are very significant; and c) to determine the impact on the utilisation of hospital emergency healthcare services of the registered population, in comparison to the non-resident population, in two areas where tourist numbers are very significant.

Methods

An ecological study design was employed. We analysed the Healthcare Districts of the Costa del Sol and the island of Menorca. Both are Spanish territories in the Mediterranean region.

Results

In the two areas analysed, the correlation coefficient between the MSW ratio and admissions to hospital emergency departments exceeded 0.9, with p < 0.001. On the basis of MSW generation ratios, obtained for a control zone and also measured in neighbouring countries, we estimated the real population. For the summer months, when tourist activity is greatest and demand for emergency healthcare at hospitals is highest, this value was found to be double that of the registered population.

Conclusion

The MSW indicator, which is both ecological and indirect, can be used to estimate the real population in areas where population levels vary significantly during the year. This parameter is of interest in planning and dimensioning the provision of healthcare services.

Ethnic variation of Fc gamma receptor polymorphism in Sami and Norwegian populations

Receptors for the Fc domain of IgG (Fc gammaR) play a critical role in linking cellular and humoral immunity. The various Fc gammaR genotypes may contribute to differences in infectious and immune-related diseases in various ethnic populations. The Samis are the aboriginal inhabitants of Norway and Fennoscandinavia and differ ethnically from the Norwegians. The distribution of various immune-related diseases has been reported to differ between Sami and Norwegians. This is the first study to evaluate the distribution of Fc gammaR polymorphisms in a Sami population. Two hundred Samis were genotyped for polymorphisms in the Fc gammaRIIA, Fc gammaRIIIA and Fc gammaRIIIB genes. The genotype and allele frequencies were compared with those of 272 healthy Norwegians. The Sami and Norwegian Fc gammaRIIA, Fc gammaRIIIA and Fc gammaRIIIB genotypes differed significantly. The Samis had higher frequencies of the Fc gammaRIIa-H/H131, Fc gammaRIIIa-F/F158 and Fc gammaRIIIb-NA1/NA1 genotypes. The Fc gammaR genotypes were non-randomly distributed in both populations. These findings may be important for the prevalence of autoimmune and infectious diseases in the two populations.

Saami and Berbers--an unexpected mitochondrial DNA link

The sequencing of entire human mitochondrial DNAs belonging to haplogroup U reveals that this clade arose shortly after the "out of Africa" exit and rapidly radiated into numerous regionally distinct subclades. Intriguingly, the Saami of Scandinavia and the Berbers of North Africa were found to share an extremely young branch, aged merely approximately 9,000 years. This unexpected finding not only confirms that the Franco-Cantabrian refuge area of southwestern Europe was the source of late-glacial expansions of hunter-gatherers that repopulated northern Europe after the Last Glacial Maximum but also reveals a direct maternal link between those European hunter-gatherer populations and the Berbers.

Gastro-enteritis outbreak among Nordic patients with psoriasis in a health centre in Gran Canaria, Spain: a cohort study

Background

Between November 2 and 10, 2002 several patients with psoriasis and personnel staying in the health centre in Gran Canaria, Spain fell ill with diarrhoea, vomiting or both. Patient original came from Norway, Sweden and Finland. The patient group was scheduled to stay until 8 November. A new group of patients were due to arrive from 7 November.

Methods

A retrospective cohort study was conducted to assess the extent of the outbreak, to identify the source and mode of transmission and to prevent similar problems in the following group.

Results

Altogether 41% (48/116) of persons staying at the centre fell ill. Norovirus infection was suspected based on clinical presentations and the fact that no bacteria were identified. Kaplan criteria were met. Five persons in this outbreak were hospitalised and the mean duration of diarrhoea was 3 days. The consequences of the illness were more severe compared to many other norovirus outbreaks, possibly because many of the cases suffered from chronic diseases and were treated with drugs reported to affect the immunity (methotrexate or steroids).

During the two first days of the outbreak, the attack rate was higher in residents who had consumed dried fruit (adjusted RR = 3.1; 95% CI: 1.4–7.1) and strawberry jam (adjusted RR = 1.9; 95% CI: 0.9–4.1) than those who did not. In the following days, no association was found. The investigation suggests two modes of transmission: a common source for those who fell ill during the two first days of the outbreak and thereafter mainly person to person transmission. This is supported by a lower risk associated with the two food items at the end of the outbreak.

Conclusions

We believe that the food items were contaminated by foodhandlers who reported sick before the outbreak started. Control measures were successfully implemented; food buffets were banned, strict hygiene measures were implemented and sick personnel stayed at home >48 hours after last symptoms.

Ethnic differences in daily smoking in Malmö, Sweden. Varying influence of psychosocial and economic factors

BACKGROUND

The aim was to investigate ethnic differences in daily smoking in Malmö, Sweden, and whether these differences could be explained by psychosocial and economic conditions.

METHODS

The public health survey in Malmö 1994 is a cross-sectional study. A total of 5,600 individuals aged 20-80 years were randomly chosen to respond to a postal questionnaire. The participation rate was 71%. The study population was divided into seven categories according to country of birth; Sweden, Denmark/Norway, other Western countries, former Yugoslavia, Poland, Arabic-speaking countries and all other countries. A multivariate analysis was performed using a logistic regression model in order to investigate the importance of possible confounders on the ethnic differences in daily smoking. Finally, variables measuring social network, social support and economic conditions were introduced.

RESULTS

The prevalence of daily smoking was significantly higher among both men and women born in Denmark/Norway (39.1% and 37.0%), men born in other Western countries (32.9%), Poland (34.0%) and Arabic-speaking countries (36.4%) than among Swedish men (21.7%) and women (23.8%). Women born in Arabic-speaking countries had a significantly lower smoking prevalence (7.1%). The multivariate analysis, including age, education and snuff, did not affect these results. A reduction of the odds ratio of daily smoking was observed for men born in Arabic-speaking countries and Poland after the introduction of the psychosocial and economic factors in the model. Only small changes were observed for women.

CONCLUSION

There were significant ethnic group differences in daily smoking. Psychosocial and economic conditions in Sweden may be of importance in some ethnic groups.

Cancer risks in second-generation immigrants to Sweden

We used the nationwide Swedish Family-Cancer Database to analyze cancer risks in Sweden-born descendants of immigrants from European and North American countries. Our study included close to 600,000 0-66-year-old descendants of an immigrant father or mother. We calculated standardized incidence ratios (SIRs) and 95% confidence intervals (CIs) for 17 cancer sites using native Swedes as a reference. All cancer was marginally below the Swedish incidence in offspring of immigrant origin. Decreased SIRs were observed for breast cancer among Norwegian descendants, melanoma among descendants of Hungarian fathers and ovarian and bladder cancer among descendents of Finnish mothers, all consistent with the difference in cancer incidence between Swedes and the indigenous populations. Cervical cancer was increased in daughters of Danish men, whereas thyroid cancer and non-Hodgkin's lymphoma were in excess in offspring of parents of Yugoslav and Asian descent. Even these results agreed with the high incidence rates in parents compared to Swedes, except that for non-Hodgkin's lymphoma other explanations are needed; these may be related to immune malfunction. Comparison of the results between the first- and the second-generation immigrants suggest that the first 2 decades of life are important in setting the pattern for cancer development in subsequent life. Birth in Sweden sets the Swedish pattern for cancer incidence, irrespective of the nationality of descent, while entering Sweden in the 20s is already too late to influence the environmentally imprinted program for the cancer destiny.

Distribution of the CCR5 gene 32-basepair deletion in West Europe. A hypothesis about the possible dispersion of the mutation by the Vikings in historical times

The chemokine receptor CCR5 constitutes the major coreceptor for the macrophage-tropic strains of HIV-1. A mutant allele of the CCR5 gene named Delta32 was shown to provide to homozygotes a strong resistance against infection by HIV. The frequency of the Delta32 allele was collected in 7328 noninfected unrelated individuals from 31 different European populations, and in Cyprus, Turkey, Daghestan, and North-Africa. The Delta32 allele was found in all populations studied, with a mean frequency of about 8.0%. A north to south gradient correlating latitude with Delta32 allelic frequencies was found (r = 0.795, p < 10(-9)), with highest allele frequencies in Nordic countries. We hypothesized that the Delta32 allele was disseminated in Europe by the Vikings during the eighth to the tenth centuries, because the most elevated values of this variant are actually found in their actual populations, and because they raided during the corresponding period in most European countries.

mtDna and the islands of the North Atlantic: estimating the proportions of Norse and Gaelic ancestry

A total of 1,664 new mtDNA control-region sequences were analyzed in order to estimate Gaelic and Scandinavian matrilineal ancestry in the populations of Iceland, Orkney, the Western Isles, and the Isle of Skye and to investigate other aspects of their genetic history. A relative excess of private lineages in the Icelanders is indicative of isolation, whereas the scarcity of private lineages in Scottish island populations may be explained by recent gene flow and population decline. Differences in the frequencies of lineage clusters are observed between the Scandinavian and the Gaelic source mtDNA pools, and, on a continent-wide basis, such differences between populations seem to be associated with geography. A multidimensional scaling analysis of genetic distances, based on mtDNA lineage-cluster frequencies, groups the North Atlantic islanders with the Gaelic and the Scandinavian populations, whereas populations from the central, southern, and Baltic regions of Europe are arranged in clusters in broad agreement with their geographic locations. This pattern is highly significant, according to a Mantel correlation between genetic and geographic distances (r=.716). Admixture analyses indicate that the ancestral contributions of mtDNA lineages from Scandinavia to the populations of Iceland, Orkney, the Western Isles, and the Isle of Skye are 37.5%, 35.5%, 11.5%, and 12.5%, respectively.

An ethnic role for chronic, but not acute, graft-versus-host disease after HLA-identical sibling stem cell transplantation

Among 424 HLA identical siblings undergoing stem cell transplantation, 364 were Scandinavians and 60 represented other ethnic groups. The cumulative probabilities of acute graft-versus-host disease grades II-IV were similar in both groups, 17% in Scandinavians and 12% in the others, p = 0.4. In a multivariate analysis, less effective immune suppression with cyclosporine or methotrexate alone (p = 0.001), recipient seropositive for three to four herpes viruses (p = 0.004), CMV-seropositive recipient (p = 0.05) and early engraftment (before day 15) (p = 0.05) were independent risk-factors for acute GVHD grades II-IV. The cumulative probabilities of chronic GVHD were 47% and 68% in the two ethnic populations, respectively (p = 0.004). In multivariate analysis, higher patient age (p < 0.001), non-Scandinavian population (p < 0.001) and immunised female donor to male recipient (p = 0.03) were independent risk factors for chronic GVHD. The higher incidence of chronic GVHD could not be explained by differences in HLA antigen frequencies. The cumulative probabilities of relapse were 37% in the both groups. This suggests that the Scandinavian population is more homogeneous with regard to minor histocompatibility antigens important for chronic, but not acute GVHD.

Estimating Scandinavian and Gaelic ancestry in the male settlers of Iceland

We present findings based on a study of Y-chromosome diallelic and microsatellite variation in 181 Icelanders, 233 Scandinavians, and 283 Gaels from Ireland and Scotland. All but one of the Icelandic Y chromosomes belong to haplogroup 1 (41.4%), haplogroup 2 (34.2%), or haplogroup 3 (23.8%). We present phylogenetic networks of Icelandic Y-chromosome variation, using haplotypes constructed from seven diallelic markers and eight microsatellite markers, and we propose two new clades. We also report, for the first time, the phylogenetic context of the microsatellite marker DYS385 in Europe. A comparison of haplotypes based on six diallelic loci and five microsatellite loci indicates that some Icelandic haplogroup-1 chromosomes are likely to have a Gaelic origin, whereas for most Icelandic haplogroup-2 and -3 chromosomes, a Scandinavian origin is probable. The data suggest that 20%-25% of Icelandic founding males had Gaelic ancestry, with the remainder having Norse ancestry. The closer relationship with the Scandinavian Y-chromosome pool is supported by the results of analyses of genetic distances and lineage sharing. These findings contrast with results based on mtDNA data, which indicate closer matrilineal links with populations of the British Isles. This supports the model, put forward by some historians, that the majority of females in the Icelandic founding population had Gaelic ancestry, whereas the majority of males had Scandinavian ancestry.

mtDNA and the origin of the Icelanders: deciphering signals of recent population history

Previous attempts to investigate the origin of the Icelanders have provided estimates of ancestry ranging from a 98% British Isles contribution to an 86% Scandinavian contribution. We generated mitochondrial sequence data for 401 Icelandic individuals and compared these data with >2,500 other European sequences from published sources, to determine the probable origins of women who contributed to Iceland's settlement. Although the mean number of base-pair differences is high in the Icelandic sequences and they are widely distributed in the overall European mtDNA phylogeny, we find a smaller number of distinct mitochondrial lineages, compared with most other European populations. The frequencies of a number of mtDNA lineages in the Icelanders deviate noticeably from those in neighboring populations, suggesting that founder effects and genetic drift may have had a considerable influence on the Icelandic gene pool. This is in accordance with available demographic evidence about Icelandic population history. A comparison with published mtDNA lineages from European populations indicates that, whereas most founding females probably originated from Scandinavia and the British Isles, lesser contributions from other populations may also have taken place. We present a highly resolved phylogenetic network for the Icelandic data, identifying a number of previously unreported mtDNA lineage clusters and providing a detailed depiction of the evolutionary relationships between European mtDNA clusters. Our findings indicate that European populations contain a large number of closely related mitochondrial lineages, many of which have not yet been sampled in the current comparative data set. Consequently, substantial increases in sample sizes that use mtDNA data will be needed to obtain valid estimates of the diverse ancestral mixtures that ultimately gave rise to contemporary populations.

Incidence of BRCA1 and BRCA2 mutations in Ashkenazi colorectal cancer patients: preliminary study

BACKGROUND

Mutations in BRCA genes are associated with an elevated incidence of colorectal cancer (CRC). While 20% of CRC patients have a familial history of colonic malignancies, in only 5% is the genetic setting understood. Thus, a majority of these patients lack any known genetic marker. Our aim was to explore the relevance of BRCA mutations to serve as such markers in the genetic screening and counseling of CRC patients.

PATIENTS AND METHODS

136 consecutive Israeli Jewish patients with sporadic CRC were screened for BRCA "Ashkenazi mutations": 185delAG, 5382insC and 6174delT. Carrier status was evaluated employing PCR, restriction analysis, SSCP and a Pronto BRCA kit.

RESULTS

We found one 185delAG and two 6174delT carriers, altogether three Ashkenazi carriers out of 87 Ashkenazi patients tested, 3.5%. No carriers were found among the Arabs and non-Ashkenazi Jews surveyed.

CONCLUSIONS

Our preliminary results show elevated rates of BRCA "Ashkenazi mutations" in Ashkenazi CRC patients, suggesting their involvement in CRC carcinogenesis. An implementation of a wider study will establish the role of these mutations as genetic markers for CRC.

Detailed mapping of the phosphomannomutase 2 (PMM2) gene and mutation detection enable improved analysis for Scandinavian CDG type I families

The gene for carbohydrate-deficient glycoprotein syndrome type I (CDG1) has previously been localised by us close to marker D16S406 in chromosome region 16p13.2-3. We also presented data indicating a strong founder mutation associated with a specific haplotype in CDG I patients from western Scandinavia. The phosphomannomutase 2 (PMM2) gene was recently put forward as a likely CDG1 candidate gene. We have now shown that the specific haplotype is associated with the PMM2 mutation 357C > A. Using data from radiation hybrid panel we have refined the position of the PMM2 gene to very close to marker D16S3020 in the interval between D16S406 and AFM282ze1 on the distal side and D16S3087 on the proximal side. Due to the severity of the disease many families request prenatal diagnostic services for CDG I. In the meantime, until the mutation spectrum is fully examined, we propose the combined use of mutation analysis and linkage analysis with polymorphic markers as diagnostic tools for Scandinavian CDG I families requesting prenatal diagnosis. Using this strategy we have to date successfully performed 15 prenatal diagnoses for CDG I.

Influence of ethnic factors on behavior problems in indigenous Sami and majority Norwegian adolescents

OBJECTIVE

To explore the relationship between behavior problems and ethnic factors in indigenous minority Sami and Norwegian majority adolescents in northern Norway.

METHOD

The Youth Self-Report (YSR) was completed by 249 Sami and 210 Norwegian students in junior high school, aged 13 to 16 years. Parents completed the Child Behavior Checklist (CBCL). Behavior problems were assessed in relation to ethnicity and ethnic context (geographic region and family context).

RESULTS

Rates of behavior problems (CBCL and YSR) were generally high in both ethnic groups and were highest among girls. Sami adolescents, particularly those living in assimilated ethnic communities, reported more behavior problems than Norwegian adolescents.

CONCLUSION

Ethnic factors have significant impact on behavior problems in indigenous minority adolescents living in a multiethnic context.

Cancer risk among Scandinavian immigrants in the US and Scandinavian residents compared with US whites, 1973-89

Studies of migrants can generate hypotheses on the aetiology of cancer. Such studies are most informative when cancer incidence data are available both in the source and host country. We compared the incidence rate ratio of cancers (stomach, lung, female breast, colorectal and prostate) in Scandinavian immigrants to the US to US-born whites, using data from the SEER registry, 1973-89. Odds ratios (OR) for cancer sites in relation to birthplace were estimated using logistic regression. We also compared rate ratios (RR) for Scandinavian and US residents, using Poisson regression. Compared with US whites, most Scandinavian migrant groups had elevated OR for stomach cancer (1.58 to 3.92), and lower OR for lung cancer (0.38 to 0.88). Similarly, compared with US whites, residents of most Scandinavian countries had elevated RR for stomach cancer (1.47 to 3.33) and lower RR for lung cancer (0.27 to 0.97). Therefore, risk factors for lung and stomach cancers, such as smoking habits and Helicobacter pylori infection, respectively, may have been retained upon migration. Risks for breast, colorectal and prostate cancer among immigrants approached risks in the US (contrasting Scandinavian risks) suggesting assimilation of environmental and/or lifestyle factors.

[D-vitamin and vitamin D deficiency among Asian immigrants]

Vitamin D deficiency, often complicated by osteomalacia, among Asian immigrants (especially females) is now also recognized in the Nordic countries. The article reviews the history of vitamin D featuring its discovery as well as a contemporary perspective, and describes the complex etiology of the disease. The symptoms, diagnostic approach and recommended treatment are also summarized.

Phenylketonuria and the peoples of Northern Ireland

The comparison of regional patterns of recessive disease mutations is a new source of information for studies of population genetics. The analysis of phenylketonuria (PKU) mutations in Northern Ireland shows that most major episodes of immigration have left a record in the modern genepool. The mutation 165T can be traced to the Palaeolithic people of western Europe who, in the Mesolithic period, first colonised Ireland. R408W (on haplotype 1) in contrast, the most common Irish PKU mutation, may have been prevalent in the Neolithic farmers who settled in Ireland after 4500 BC. No mutation was identified that could represent European Celtic populations, supporting the view that the adoption of Celtic culture and language in Ireland did not involve major migration from the continent. Several less common mutations can be traced to the Norwegian Atlantic coast and were probably introduced into Ireland by Vikings. This indicates that PKU has not been brought to Norway from the British Isles, as was previously argued. The rarity in Northern Ireland of IVS12nt1, the most common mutation in Denmark and England, indicates that the English colonialization of Ireland did not alter the local genepool in a direction that could be described as Anglo-Saxon. Our results show that the culture and language of a population can be independent of its genetic heritage, and give some insight into the history of the peoples of Northern Ireland.

Autosomal dominant spinocerebellar ataxia with sensory axonal neuropathy (SCA4): clinical description and genetic localization to chromosome 16q22.1

The hereditary ataxias represent a clinically and genetically heterogeneous group of neurodegenerative disorders. Various classification schemes based on clinical criteria are being replaced as molecular characterization of the ataxias proceeds; so far, seven distinct autosomal dominant hereditary ataxias have been genetically mapped in the human genome. We report linkage to chromosome 16q22.1 for one of these genes (SCA4) in a five-generation family with an autosomal dominant, late-onset spinocerebellar ataxia; the gene is tightly linked to the microsatellite marker D16S397 (LOD score = 5.93 at theta = .00). In addition, we present clinical and electrophysiological data regarding the distinct and previously unreported phenotype consisting of ataxia with the invariant presence of a prominent axonal sensory neuropathy.

Epidemiology of classic Kaposi's sarcoma in Denmark between 1970 and 1992

BACKGROUND

Studies have suggested that the incidence of classic Kaposi's sarcoma (KS) varies considerably within Europe. The epidemiology of classic KS in Denmark was described for the period between 1970 and 1992 and association with marital status and country of origin were evaluated.

METHODS

A descriptive epidemiology study was carried out using data from the Danish Cancer Registry and from all Danish pathology departments. The effects of marital status and of immigration were evaluated in a case-control study with sex- and age-matched controls for 50 cases of classic KS.

RESULTS

A total of 59 patients with classic KS, 34 men, 25 women, were identified between 1970 and 1992, yielding world standardized incidence rates of 0.40 and 0.22 per 1,000,000 population among men and women, respectively. Among men, a larger proportion of the patients with classic KS were of non-Danish origin [odds ratio (OR) = 3.8, 95% confidence interval (CI) = 1.5-9.6]. No excess of foreign born persons was observed among women with KS. Never-married men were at a markedly increased risk for classic KS (OR = 2.8, 95% CI = 1.2-6.7). This risk was, however, restricted to men younger than 60 years (OR = 18.8, 95% CI 3.4-104.8), whereas no increased risk was observed in men age 60 years or older nor was there an increased risk in women.

CONCLUSIONS

Classic KS is a rare disease in Denmark. However, men, immigrants and never-married men age 60 years or younger experienced an excess risk. Even though the latter finding might reflect an association with male homosexuality, the observation should be interpreted with caution due to the limited number of observations.

Moyamoya disease in patients of Finno-Ugric origin

The terms moyamoya disease, moyamoya syndrome and moyamoya phenomenon can be found dispersed throughout the literature. The diagnostic criteria for moyamoya disease are: (1) stenosis or occlusion of the anterior cerebral, middle cerebral and internal carotid arteries, (2) an abnormal vascular network near these arteries and (3) bilateral findings. When only the two first conditions are present, the term moyamoya syndrome is used. The incidence of moyamoya disease is high in the Mongol race, although the moyamoya syndrome is more frequently reported among Caucasians. In the last two decades 41 cases of moyamoya were diagnosed in two Hungarian and two Scandinavian hospitals, respectively. Thirty-one patients were operated on 12 unilaterally and 19 bilaterally--either with extracranial/intracranial bypass (29 cases) or with encephalomyosynangiosis (2 cases). After a mean follow-up of seven years, 67.7% of the operated cases were symptom-free or neurologically improved. The majority of the patients had moyamoya disease and turned out to be of Finno-Ugric or Lapplandish ancestry. These people originally migrated from the East and belong to the Ural-Altaic family. Our findings suggest that while the moyamoya syndrome is found in different races, the moyamoya disease may be limited to people of Eastern (Mongol) origin. Revascularization surgery may be of benefit to patients with moyamoya.

The dissemination of multiple sclerosis: a Viking saga? A historical essay

The highest prevalence rates for multiple sclerosis are found in Iceland, Scandinavia, the British Isles, and the countries settled by their inhabitants and their descendants, that is, the United States, Canada, Australia, and New Zealand. This suggests that the Vikings may have been instrumental in disseminating the genetic susceptibility to the disease in those areas as well as in other parts of the world. The Vikings raided in most European countries and settled in Normandy and in Sicily and southern Italy. They engaged in trade with the Arabs along the river routes to the Caucasus and to the Black and Caspian Seas and penetrated into Persia, India, and probably China. They also migrated to the East and established the Russian state. Under the name Varangians, they became part of the Byzantine army and were active in all of the military activities of the Byzantine Empire. They participated in the Crusades. Russians, many of Scandinavian origin, also constituted a regiment of the Mongol army and roamed throughout that empire as well. The custom of capturing and keeping or selling women and children, which was widespread in the early Middle Ages, as well as the flourishing slave trade in men, were important factors in this genetic dissemination.