Melanesian Populations Research Articles

Total adiponectin in indigenous Melanesians on Kitava.

Experimental and small human studies have indicated that high total adiponectin levels have beneficial cardiometabolic effects. In contrast, however, high total adiponectin levels are also associated with higher all-cause and cardiovascular mortality in thoroughly adjusted epidemiological studies. To gain further insight into these seemingly contradictory results, we report results on total adiponectin from the indigenous Melanesian population of Kitava, Trobriand Islands, Papua New Guinea, where an apparent absence of cardiometabolic disease has been previously reported. Fasting levels of serum total adiponectin were measured cross-sectionally in ≥40-year-old Kitavans (n = 102) and Swedish controls matched for age and sex (n = 108). Multivariable linear regression was used for the analysis of associations with total adiponectin when controlled for group, sex, smoking, hypertension and/or type 2 diabetes, age, and body mass index. Total adiponectin was lower for Kitavans compared to Swedish controls (Median [Mdn] 4.6 μg/mL, range 1.0-206 μg/mL and Mdn 9.7 μg/mL, range 3.1-104 μg/mL, respectively, r = .64, p < .001). Lower total adiponectin was associated with Kitavan group, male sex (only in Swedish controls), smoking (only in Kitavans and Swedish controls combined), younger age (not in Swedish controls), higher BMI, lower total, low-density lipoprotein, high-density lipoprotein (HDL) (only in Kitavans and Swedish controls combined), and non-HDL cholesterol, and higher anti-PC IgG (only in Kitavans and Swedish controls combined). Total adiponectin in Kitavans was significantly lower than in Swedish controls.

‘Mind the gap’ in using multiplex gap-PCR for the diagnosis of alpha thalassaemia in Polynesian, Melanesian and Aboriginal populations

‘Mind the gap’ in using multiplex gap-PCR for the diagnosis of alpha thalassaemia in Polynesian, Melanesian and Aboriginal populations

Fossil detectives: How the 2022 noble prize winners unearthed the journey of human evolution

What do scraps of bones discovered in a deserted Siberian Cave in Russia have to do with us? Or how do a few fragments of teeth in Gibraltar, an isolated British overseas territory located at the southern tip of the Iberian Peninsula, have to do with the genetic legacy of today’s living people across Asia? Well, it seems that about 40,000 years back, we humans were not the only inhabiting hominids on this planet Earth; we had other mysterious cousins, at least two of them known so far, who had left enough evidence and trails of DNA for the scientist to ponder. Like crime cases that run cold due to lack of solid evidence, paleontologists often tumble when encountering roadblocks; until Swedish Geneticists Svante Pääbo painstakingly developed the necessary tools and techniques to trace back our origin, 15000 years back when perhaps the three hominids even crisscrossed each other’s path. The Desonovians, the Nearthandals, and the modern-day humans. The two ancestors of humans perhaps arose from a common origin several thousand years back. We now know that the Desinovinans diverged from their close relatives, the Neanderthals, around 400,000 years ago, while they both diverged from modern Homo sapiens around 800,000 years ago. The Neanderthals were populated in Europe and Asia, while the more elusive Desonovians were restricted to Siberia, in regions of eastern and southern Eurasia. Genomic homology studies revealed that the Denisova’s mitochondrial DNA differs from that of modern humans by 385 bases, whereas the difference with Neanderthals is around 202 bases. These numbers stand out from the difference between chimpanzees and modern humans, approximately 1462 base pairs. It is now conclusively known that sometimes in prehistoric times, there had been an event of DNA mixing between the Denisovans and modern humans, an event of actual sexual mating. The percentage of Denisovan DNA is highest in the Melanesian population (Melanesians are the indigenous inhabitants of Melanesia, from New Guinea to the Fiji Islands), lower in other Southeast Asian and Pacific Islander populations, with hardly any DNA detectable in other populations in the world. What is enigmatic is how this human cousin got extinct. Possibly a competition for resources was likely one reason the Denisovans went extinct. The evolutionary trajectory of the Nearthandals followed a different route. At least, two different groups of Neanderthals who lived in Southern Siberia seem to have migrated from Eastern Europe. Not only that, just that Denisovans also interbred with modern-day humans. This interesting phenomenon is called Introgression. It explains why modern-day humans have some Neanderthal DNA, roughly about 3%. Human ancestors only lived in Africa until they decided to migrate to Europe some 45,000 years ago. It’s there where they encountered its other ancestors, the Neanderthals (Homo neanderthalensis). Eventually, they mated and produced offspring resulting in Introgression. Since this mating event happened outside Africa, present-day African people have no traces of Neanderthal DNA. However, due to interesting adaptive advantages, modern-day humans (outside Africa) still retained 3% of Neanderthal DNA, a spectacular observation even 40,000 years after they might have last mated. This is called adaptive Introgression. This is also where Darwin’s principles of natural selection come in. Retaining the 3% Neanderthals might serve some advantage to Modern Humans for better adaptations, something that the sickle mutated DNA at one allele (heterozygous) got positively adapted in Africa due to its protective effect against the malarial parasite in malariaendemic areas. Things can get even interesting and weird with the findings that hybrid individuals were discovered who carried both the Denisovan as well as Neanderthal DNA. That’s what the team, led by palaeogeneticists Slon et al., reported in Nature. Named as “Denny,” thischild seems to be born from a Neanderthal mother and a Desinovan dad, some 90,000 years back. Denny seems to be born out of mating of two extinct hominid ancestors, acquiring one set of chromosomes from a Neanderthal and the other from a Denisovan. Shaped by evolution and driven by its migratory nature, present-day human is the cumulative outcome of thousands of years of man’s struggle for its survival. Driven by the changing environmental its migration journey picked with it traces of DNA from its ancestral cousins that it encountered. Meticulous investigation of this apparently insignificant DNA holds the secret of thousands of years of human history and human migration. Relentless efforts by Prof Svante Pääbo and other researchers have shed light on our ancestral autobiography.

Generational issues in linking family farming production, traditional food in diet, physical activity and obesity in Pacific Islands countries and territories: the case of the Melanesian population on Lifou Island

In the Melanesian culture, traditional activities are organized around family farming, although the lifestyle transition taking place over the last several decades has led to imbalances in diet and physical activity, with both leading to obesity. The aim of this interdisciplinary study was to understand the links between family farming (produced, exchanged, sold, and consumed food), diet (focused on produced, hunted, and caught food), physical activity (sedentary, light, and moderate-to-vigorous physical activity) and obesity in Melanesian Lifou Island families (parents and children). Forty families, including 142 adults and children, completed individual food frequency questionnaires, wore tri-axial accelerometers for seven continuous days, and had weight and height measured with a bio-impedance device. A family farming questionnaire was conducted at the household level concerning family farming practices and sociodemographic variables. Multinomial regression analyses and logistic regression models were used to analyze the data. Results showed that family farming production brings a modest contribution to diet and active lifestyles for the family farmers of Lifou Island. The drivers for obesity in these tribal communities were linked to diet in the adults, whereas parental socioeconomic status and moderate-to-vigorous physical activity were the main factors associated to being overweight and obesity in children. These differences in lifestyle behaviors within families suggest a transition in cultural practices at the intergenerational level. Future directions should consider seasonality and a more in-depth analysis of diet including macro- and micro- nutrients to acquire more accurate information on the intergenerational transition in cultural practices and its consequences on health outcomes in the Pacific region.

The 2020 New Caledonia Referendum: The Slow March to Independence?

ABSTRACT At a second referendum in October 2020 the majority of the eligible population of New Caledonia voted to remain with France rather than choose independence. After violent conflict in the 1980s, two accords brought a process of ‘rebalancing’ over 30 years, aimed at creating a ‘common destiny’ primarily between the Indigenous Melanesian Kanak population and European settlers, culminating in a series of referendums on independence. Despite some economic development in the largely rural and regional areas dominated by Kanaks, a first 2018 referendum campaign highlighted persistent acute divisions between Kanaks who sought independence, and loyalists who preferred stability, security, and preservation of the status quo. The relatively close outcome of that first referendum, 56 per cent against independence as compared to 44 per cent in favour, was followed by a second still closer outcome, 53 per cent against and 47 per cent in favour. Whereas most of the world’s remaining non-decolonized states have avoided the path of secession or full independence, New Caledonia appeared to be edging towards independence. Nonetheless divisions were hardening. With a third referendum on independence posited for 2022, and the election of a majority pro-independence government in February 2021, New Caledonia faces the alternatives of independence, a new accord agreed between loyalists and pro-independence parties, or a future continuation of the power-sharing institutions created by the 1998 Noumea Accord.

Genetic evidence and historical theories of the Asian and African origins of the present Malagasy population.

The origin of the Malagasy population has been a subject of speculation since the 16th century. Contributions of African, Asian, Indian, Melanesian, Arabic and Persian populations have been suggested based on physical and cultural anthropology, oral tradition, linguistics and later also by archaeology. In the mid-20th century, increased knowledge of heredity rules and technical progress enabled the identification of African and Asian populations as main contributors. Recent access to the genomic landscape of Madagascar demonstrated pronounced regional variability in the relative contributions of these two ancestries, yet with significant presence of both African and Asian components throughout Madagascar. This article reviews the extent to which genetic results have settled historical questions concerning the origin of the Malagasy population. After an overview of the early literature, the genetic results of the 20th and 21th centuries are discussed and then complemented by the latest results in genome-wide analyses. While there is still much uncertainty regarding when, how and the circumstances under which the ancestors of the modern Malagasy population arrived on the island, we propose a scenario based on historical texts and genomic results.

SEQUENTIAL IMPORTANCE SAMPLING FOR MULTIRESOLUTION KINGMAN-TAJIMA COALESCENT COUNTING.

Statistical inference of evolutionary parameters from molecular sequence data relies on coalescent models to account for the shared genealogical ancestry of the samples. However, inferential algorithms do not scale to available data sets. A strategy to improve computational efficiency is to rely on simpler coalescent and mutation models, resulting in smaller hidden state spaces. An estimate of the cardinality of the state-space of genealogical trees at different resolutions is essential to decide the best modeling strategy for a given dataset. To our knowledge, there is neither an exact nor approximate method to determine these cardinalities. We propose a sequential importance sampling algorithm to estimate the cardinality of the sample space of genealogical trees under different coalescent resolutions. Our sampling scheme proceeds sequentially across the set of combinatorial constraints imposed by the data, which in this work are completely linked sequences of DNA at a non recombining segment. We analyze the cardinality of different genealogical tree spaces on simulations to study the settings that favor coarser resolutions. We apply our method to estimate the cardinality of genealogical tree spaces from mtDNA data from the 1000 genomes and a sample from a Melanesian population at the β-globin locus.

Another Pause for Independence? The 2018 New Caledonia Referendum

ABSTRACTNew Caledonia is a distinctive French overseas territory with significant interest in independence. It reflects the legacy of a settler colony, where Melanesians were displaced to reservations in the nineteenth century. Pressure for independence comes almost exclusively from the minority Kanak (Melanesian) population. In the 1980s a violent and unsuccessful struggle for independence was defeated and the Matignon Accords, followed by the Noumea Accord, sought to maintain peace and ‘rebalance’ social and economic life over a period of 30 years in favour of the Kanak population and less developed regions of the country. Kanaks acquired greater stakes in the important nickel industry, but became divided between those who achieved economic success and those who perceived the ‘modern’ economy as means of destroying Kanak unity and cultural traditions. Uneven development has not been reduced and urbanisation emphasised inequality and relative deprivation. The Accords culminated in a referendum on independence in November 2018 with a significant majority voting against it. Voting broadly followed ethnic lines with Europeans expressing strong support for remaining French, and fearing instability and loss of French financial support, and Kanaks arguing that independence was a historical and cultural necessity. Two more referendums may follow in the next four years but independence is unlikely to be the outcome.

Nutrition and its role in human evolution.

Our understanding of human evolution has improved rapidly over recent decades, facilitated by large-scale cataloguing of genomic variability amongst both modern and archaic humans. It seems clear that the evolution of the ancestors of chimpanzees and hominins separated 7-9million years ago with some migration out of Africa by the earlier hominins; Homo sapiens slowly emerged as climate change resulted in drier, less forested African conditions. The African populations expanded and evolved in many different conditions with slow mutation and selection rates in the human genome, but with much more rapid mutation occurring in mitochondrial DNA. We now have evidence stretching back 300000years of humans in their current form, but there are clearly four very different large African language groups that correlate with population DNA differences. Then, about 50000-100000years ago a small subset of modern humans also migrated out of Africa resulting in a persistent signature of more limited genetic diversity amongst non-African populations. Hybridization with archaic hominins occurred around this time such that all non-African modern humans possess some Neanderthal ancestry and Melanesian populations additionally possess some Denisovan ancestry. Human populations both within and outside Africa also adapted to diverse aspects of their local environment including altitude, climate, UV exposure, diet and pathogens, in some cases leaving clear signatures of patterns of genetic variation. Notable examples include haemoglobin changes conferring resistance to malaria, other immune changes and the skin adaptations favouring the synthesis of vitamin D. As humans migrated across Eurasia, further major mitochondrial changes occurred with some interbreeding with ancient hominins and the development of alcohol intolerance. More recently, an ability to retain lactase persistence into adulthood has evolved rapidly under the environmental stimulus of pastoralism with the ability to husband lactating ruminants. Increased amylase copy numbers seem to relate to the availability of starchy foods, whereas the capacity to desaturase and elongate monounsaturated fatty acids in different societies seems to be influenced by whether there is a lack of supply of readily available dietary sources of long-chain polyunsaturated fatty acids. The process of human evolution includes genetic drift and adaptation to local environments, in part through changes in mitochondrial and nuclear DNA. These genetic changes may underlie susceptibilities to some modern human pathologies including folate-responsive neural tube defects, diabetes, other age-related pathologies and mental health disorders.

A prospective study on measurement of common bile duct, cystic duct and its anatomical variations in the melanesian population of papua new Guinea

A prospective study on measurement of common bile duct, cystic duct and its anatomical variations in the melanesian population of papua new Guinea

Pilot Study of Isoniazid Acetylation in Melanesian Healthy Subject from Indonesia

Objective: Isoniazid (INH) is metabolized by N-acetyl transferase-2 into acetyl isoniazid (Ac-INH). The acetylation rate is different in each ethnic, therefore it is very interesting to study of INH acetylation. The aims of this study were to synthesize Ac-INH and the produced Ac-INH was used as a working standard for the pilot study of INH acetylation in Melanesian healthy subjects from Indonesia. Methods: Ac-INH can be simply synthesized by acetylation reactions between INH and acetic anhydride. The synthesis results were characterized by organoleptic observation, purity test, UV-Vis spectrophotometry analysis, FTIR analysis, and mass spectrometry analysis. The pilot study of INH acetylation used high performance liquid chromatography to analyze the levels of INH and Ac-INH in blood of Melanesian healthy subjects. The acetylation rate of INH was determined by the ratio between Ac-INH and INH concentrations at 3 h after administration of INH. Results: The acetylation reaction to synthesize Ac-INH has been performed at temperature of 60°C for 30 min. The obtained Ac-INH had the same quality specifications with reference standard of Ac-INH. The average of ratio between of Ac-INH and INH concentrations was Conclusion: The obtained Ac-INH could be used for pilot study of INH acetylation by calculating the ratio of Ac-INH and INH concentrations in plasma subject. The subject has to be increased to represent the Melanesian population from Indonesia. Key words: Isoniazid, Acetyl isoniazid, Acetylation rate, Melanesia

Tanah Papua, Asia-Pacific news blind spots and citizen media: From the ‘Act of Free Choice’ betrayal to a social media revolution

For five decades Tanah Papua, or the West Papua half of the island of New Guinea on the intersection of Asia and the Pacific, has been a critical issue for the region with a majority of the Melanesian population supporting self-determination, and ultimately independence. While being prepared for eventual post-war independence by the Dutch colonial authorities, Indonesian paratroopers and marines invaded the territory in 1962 in an ill-fated military expedition dubbed Operation Trikora (‘People’s Triple Command’). However, this eventually led to the so-called Act of Free Choice in 1969 under the auspices of the United Nations in a sham referendum dubbed by critics as an ‘Act of No Choice’ which has been disputed ever since as a legal basis for Indonesian colonialism. A low-level insurgency waged by the OPM (Free West Papua Movement) has also continued and Jakarta maintains its control through the politics of oppression and internal migration. For more than five decades, the legacy media in New Zealand have largely ignored this issue on their doorstep, preferring to give attention to Fiji and a so-called coup culture instead. In the past five years, social media have contributed to a dramatic upsurge of global awareness about West Papua but still the New Zealand legacy media have failed to take heed. This article also briefly introduces other Asia-Pacific political issues—such as Kanaky, Timor-Leste, Papua New Guinean university student unrest, the militarisation of the Mariana Islands and the Pacific’s Nuclear Zero lawsuit against the nine nuclear powers—ignored by a New Zealand media that has no serious tradition of independent foreign correspondence.

Mitochondrial DNA variations in Austronesian-speaking populations living in the New Georgia Islands, the Western Province of the Solomon Islands.

Modern Austronesian (AN)-speaking Melanesians are considered to be derived from the admixture of indigenous non-Austronesian (NAN)-speaking people and AN-speaking people from Southeast Asia. In this study, we analyzed mitochondrial DNA (mtDNA) variations in the D-loop region for two AN-speaking Melanesian populations (Munda and Kusaghe) and an AN-speaking Micronesian population (Rawaki) in the New Georgia Islands, the Western Province of the Solomon Islands to examine their genetic similarities to AN-speaking Polynesians in Tonga and NAN-speaking Melanesians, Gidra, in Papua New Guinea. The 'Polynesian motif', which is well-characterized mtDNA marker for Polynesians, was frequently observed in Munda and Kusaghe. Of particular interest, haplogroup E1a2 + 16261, which has been rarely observed in the Solomon Islands, accounted for 12.8% in Kusaghe. It has been reported that the haplogroup E1a2 arose in Island Southeast Asia (ISEA) 9400 ± 2850 years ago. Phylogenetic and principle component analyses for 24 Oceanian populations revealed that Munda and Kusaghe populations were genetically close to Tongan population, but not to Gidra. Rawaki population showed no apparent genetic similarities to populations of Tonga and Gidra. Our results suggest that considerable gene flow from AN-speaking populations originated from Southeast Asia to indigenous Melanesians occurred in the New Georgia Islands.

Humanitarian quarantine in practice: medicine, religion and leprosy in New Caledonia

ABSTRACTMedicine and religion worked in close synchronisation during the leprosy outbreak of New Caledonia (1890–1950). Once isolation of leprosy-affected people became mandatory doctors and missionaries came together to promote a particular form of medical practice that tied charitable zeal with cutting-edge medical research, developing a sophisticated set of medical practices that catered for the soul as well as the body. Such practices went hand-in-hand with ideas developed by doctors in the earlier stages of the epidemic about the way in which the disease had entered the Kanak (local Melanesian) population. Doctors and missionaries admitted that immoral colonial channels had upset the delicate balance of local social and biological rhythms. Yet they also believed that the highly contagious nature of the outbreak was linked to the inferior state of Kanak. This paper aims to highlight the way in which the leprosaria system in New Caledonia represented a double-edged moral high-ground within the French medical colonial narrative. It tracks the complex way in which emotionally charged arguments about contagion, science and spirituality constructed an ideology of humanitarian quarantine which was used to justify a highly aggressive form of medical biocontrol.

Self-Reported Height and Weight in Oceanian School-Going Adolescents and Factors Associated With Errors.

We examined the accuracy of self-reported weight and height in New Caledonian school-going adolescents. Self-reported and measured height and weight data were collected from 665 adolescents of New Caledonia and were then compared. Multivariable logistic regressions identified the factors associated with inaccurate self-reports. Sensitivity and specificity of self-reported body mass index values to detect overweight or obesity were evaluated. Self-reported weight was significantly lower than measured weight (boys, -3.56 kg; girls, -3.13 kg). Similar results were found for height (boys, -2.51 cm; girls, -3.23 cm). Multiple regression analyses indicated that the difference between self-reported and measured height was significantly associated with ethnicity and pubertal status. Inaccurate self-reported weight was associated with socioeconomic status, place of residence, body-size perception and weight status. Screening accuracy of self-reported body mass index was low, particularly in the Melanesian subgroup. These findings should be considered when overweight is estimated in the Melanesian adolescent population at individual scale.

Polymorphisms associated with a tropical climate and root crop diet induce susceptibility to metabolic and cardiovascular diseases in Solomon Islands.

The people of the Solomon Islands represent an Austronesian (AN)-speaking population’s adaptation to a humid tropical environment and subsistence of tuberous crops. Genome-wide association studies (GWASs) of other populations (e.g. the Human Genome Diversity Project [HGDP]) have suggested the existence of genotypes adaptive to ecoregion, diet, and subsistence, and that those genotypes are also associated with metabolic and cardiovascular diseases. Recently, the incidence of non-communicable diseases has been increasing in the Solomon Islands. In the present study, we explored the association of genotypes adaptive to a tropical environment and tuberous crop diet with metabolic and cardiovascular conditions in rural and urban AN-speaking Melanesian and Micronesian populations of the Solomon Islands. A total of 561 participants were genotyped for single nucleotide polymorphisms (SNPs) potentially associated with a tropical environment (rs174570 and rs2237892) and a tuberous crop diet (rs162036, rs185819, and rs2722425). The results showed that the allele frequencies of the Solomon Islands populations adopted patterns similar to those in populations from other hot, tropical areas with a tuberous crop diet in previous studies. Furthermore, rs162036, rs185819, rs2237892, and rs2722425 were all strongly associated with one or more metabolic and cardiovascular conditions. The derived allele of rs2722425 (i.e. rs2722425-G) was significantly associated with an elevated LDL level (P = 0.000264) even after the significance level was adjusted for multiple testing (i.e., α = 0.0005). Our results suggest that the inhabitants of the Solomon Islands exhibit the effects of the tropical environment and tuberous crop diet on their allele frequencies, and that their susceptibility to metabolic and cardiovascular diseases is therefore considered to be associated with their environment and diet.

Moving past the ‘Neolithic problem’: The development and interaction of subsistence systems across northern Sahul

The ‘Neolithic problem’ refers to forager/farmer interaction in northern Australia, where despite a shared environmental inheritance with their New Guinea neighbours, Indigenous Australians seemingly rejected both the domesticates and the practices of the Melanesian horticultural economy (White, 1971). This ethnographic example is often used to suggest that hunter-gatherers elsewhere may have chosen not to adopt agriculture. However, the premise of the ‘Neolithic problem’ has been criticised for its over-reliance on the ethnographic record and on an anachronistic notion of cultural evolution, which exaggerates the dichotomy between New Guinean agriculturalists and Australian hunter-gatherers. In this paper we review the historical and theoretical treatment of the ‘Neolithic problem’ and the archaeological evidence for subsistence practices in northern Sahul spanning the past 50–60,000 years. Using niche construction theory (Rowley-Conwy and Layton, 2011) to re-examine the archaeological and ethnohistoric record, it is possible to observe the development and expansion of a variety of subsistence systems. Contrary to the premise of the ‘Neolithic problem’, the past 50–60,000 years of occupation in Sahul has seen the development of a varied array of food-producing subsistence practices in both New Guinea and Australia. However, the archaeological evidence for the expansion of horticultural practices and cultivars outside of highland New Guinea suggests a spatially and temporally narrow window for the adoption of agriculture by Indigenous populations in Cape York. Instead, the interaction between different subsistence systems in northern Sahul may have centred on the New Guinea lowlands and the Bismarck Archipelago, where, in the late Holocene, local communities interacted with other Melanesian and Austronesian populations. Whilst further archaeological investigation is required, it is clear that the image of culturally-static Indigenous Australian populations often implied in the consideration of forager/farmer interactions belongs to another era of archaeological thought.

Lack of direct evidence for natural selection at the candidate thrifty gene locus, PPARGC1A.

BackgroundThe gene PPARGC1A, in particular the Gly482Ser variant (rs8192678), had been proposed to be subject to natural selection, particularly in recent progenitors of extant Polynesian populations. Reasons include high levels of population differentiation and increased frequencies of the derived type 2 diabetes (T2D) risk 482Ser allele, and association with body mass index (BMI) in a small Tongan population. However, no direct statistical tests for selection have been applied.MethodsUsing a range of Polynesian populations (Tongan, Māori, Samoan) we re-examined evidence for association between Gly482Ser with T2D and BMI as well as gout. Using also Asian, European, and African 1000 Genome Project samples a range of statistical tests for selection (F ST, integrated haplotype score (iHS), cross population extended haplotype homozygosity (XP-EHH), Tajima’s D and Fay and Wu’s H) were conducted on the PPARGC1A locus.ResultsNo statistically significant evidence for association between Gly482Ser and any of BMI, T2D or gout was found. Population differentiation (F ST) was smallest between Asian and Pacific populations (New Zealand Māori ≤ 0.35, Samoan ≤ 0.20). When compared to European (New Zealand Māori ≤ 0.40, Samoan ≤ 0.25) or African populations (New Zealand Māori ≤ 0.80, Samoan ≤ 0.66) this differentiation was larger. We did not find any strong evidence for departure from neutral evolution at this locus when applying any of the other statistical tests for selection. However, using the same analytical methods, we found evidence for selection in specific populations at previously identified loci, indicating that lack of selection was the most likely explanation for the lack of evidence of selection in PPARGC1A.ConclusionWe conclude that there is no compelling evidence for selection at this locus, and that this gene should not be considered a candidate thrifty gene locus in Pacific populations. High levels of population differentiation at this locus and the reported absence of the derived 482Ser allele in some Melanesian populations, can alternatively be explained by multiple out-of-Africa migrations by ancestral progenitors, and subsequent genetic drift during colonisation of Polynesia. Intermediate 482Ser allele frequencies in extant Western Polynesian populations could therefore be due to recent admixture with Melanesian progenitors.Electronic supplementary materialThe online version of this article (doi:10.1186/s12881-016-0341-z) contains supplementary material, which is available to authorized users.

CYP2C19 and CYP2D6 genotypes in Pacific peoples.

The study of pharmacogenetic variants in populations which reside in Oceania has been focused mainly on CYP2C19 and CYP2D6. Statements about the high prevalence of CYP2C19 no function genotype in 'Pacific Islanders' can be found in the literature. This review article summarizes the published information about these pharmacogenes in this geographical region and highlights the differences observed between Melanesian and Polynesian populations. It is not appropriate to combine the prevalence data of pharmacogenetic variants, particularly CYP2C19, across this region. Indeed, apocryphal assumptions about CYP2C19 no function alleles and possible effect on the therapeutic activity of clopidogrel are unhelpful and reiterate the importance of assessing the individual patient rather than relying on inappropriate ethnicity-based assumptions for drug dosing decisions.

A Toll-like receptor-1 variant and its characteristic cellular phenotype is associated with severe malaria in Papua New Guinean children.

Genetic factors are likely to contribute to low severe malaria case fatality rates in Melanesian populations, but association studies can be underpowered and may not provide plausible mechanistic explanations if significant associations are detected. In preparation for a genome-wide association study, 29 candidate single-nucleotide polymorphisms (SNPs) with minor allele frequencies >5% were examined in a case-control study of 504 Papua New Guinean children with severe malaria. In parallel, an immunological substudy was performed on convalescent peripheral blood mononuclear cells (PBMCs) from cases and controls. Following stimulation with a Toll-like receptor (TLR) 1/2 agonist, effector cytokines and chemokines were assayed. The only significant genetic association observed involved a nonsynonymous SNP (TLR1rs4833095) in the TLR1 gene. A recessive (TT) genotype was associated with reduced odds of severe malaria of 0.52 (95% confidence interval (0.29-0.90), P=0.006). Concentrations of pro-inflammatory cytokines interleukin-1β and tumour necrosis factor α were significantly higher in severe malaria cases compared with healthy controls, but lower in children with the protective recessive (TT) genotype. A genetic variant in TLR1 may contribute to the low severe malaria case fatality rates in this region through a reduced pro-inflammatory cellular phenotype.