Polynesian Populations Research Articles

Human platelet antigens frequencies in Maori and Polynesian populations

Allele frequencies of human platelet antigens (HPA) reflect population history and possibility of platelet-specific alloimmunization. Here, we report on screening of variants at HPA loci for Polynesian and Maori subjects. Our aims are to evaluate new HPA genotyping methods, compile and analyse new HPA datasets for these subjects, use HPA data for tracing ancestry, migration patterns, genetic admixture and its potential influence on health. A total of 75 Maori and 25 Polynesian DNA samples were genotyped using commercial BAGene HPA-TYPE DNA-SSP kits, BLOODchip hybridization SNP assays and DNA sequence based typing. Genotyping was successful and cross validation of PCR-SSP and BLOODchip gave 100% agreement. Among the HPA loci tested, only six are dimorphic (HPA-1 to -3, -5, -6 and -15) and all others are monomorphic. The Polynesians and Maori have the 'a' allele form as the most common for all loci except HPA-15. The newly observed HPA data as well as principal coordinate analysis clearly indicate genetic contributions from both, Asia and Australasia in Maori and Polynesian populations together with recent admixture with Europeans. In addition, different prevalences of HPA alleles among Polynesian, Maori and European populations contribute towards different risk profiles for platelet-specific alloimmunization. This is the first report for these populations and our findings are of direct practical relevance for blood transfusion centres, the management of pregnancies, assessment of neonatal alloimmune thrombocytopenia and management of multi-transfused patients.

KIR diversity in three ethnic populations of Assam state, Northeast India

Killer immunoglobulin-like receptors (KIR) exhibit extensive diversity and it has been observed that populations with different ethno-history, linguistic, geographic and genetic backgrounds can differ in KIR profile. In this context, we have investigated the KIR complex in three ethnic populations-Kachari (n = 108), Ahom (n = 104) and Adivasi (n = 101) of Assam, Northeast India. The three populations had 145 distinct KIR genotypes in 313 individuals typed. The two Mongoloid populations--Kachari and Ahom had close genetic affinities with their parental East Asian groups where the Kachari clustered with Chinese populations and the Ahom in another clade clustered with Thailand Bangkok and Polynesian populations. The Adivasi differed markedly from these Mongoloid populations in having higher KIR 2DL2, 2DS2, 2DS3 and 2DS5, but lower 2DL3 (P value <0.0001). Like the other native Indian populations, the Adivasi had higher share of Bx-haplogroup and C4Tx genotype (37/101). However, unlike other Indian populations, KIR 3DS1 gene frequency was lower in Adivasi (21%) and was comparable to the African populations. The neighbor-joining dendogram generated on the basis of KIR gene frequencies of our study populations with 43 world populations also placed the Adivasi with African populations. Interestingly, the three populations in the dendogram are consistent with their migration histories. In summary, our data suggest that KIR profile of the three ethnic populations displayed ethnic diversity and was consistent with their migration history thereby supporting the concept that KIR diversity may be used to understand genetic affinity and migration history of populations.

Hypertension-susceptibility gene prevalence in the Pacific Islands and associations with hypertension in Melanesia

Human essential hypertension is partly caused by genetic factors. Angiotensinogen (AGT), G-protein β3-subunit (GNB3) and cytochrome P450 3A5 (CYP3A5) are candidate hypertension susceptibility genes and risk alleles at these loci have been thought to arise owing to human adaptation to climatic changes following the migration out-of-Africa. This study aimed to reveal the frequencies of hypertension-susceptibility genotypes in Pacific Island populations and associations of these single-nucleotide polymorphisms (SNPs) to hypertension. Genotyping was conducted for 804 individuals from Melanesian, Micronesian and Polynesian populations at SNPs in the genes encoding AGT (rs699, rs5049 and rs5051), GNB3 (rs5443) and CYP3A5*1/*3 (rs776746). Associations between these SNPs and hypertension were tested for 383 Melanesian Solomon Islanders. We found that the A/A genotype at rs5049 was a risk factor for hypertension (P=0.025) in the Melanesian Solomon Islanders; three SNPs for AGT were in linkage disequilibrium. The ancestral alleles of rs699, rs5051 and rs776746, and the derived allele of rs5443 were as frequent in the populations surveyed here as in other equatorial populations. Although other polymorphisms associated with hypertension and additional populations remain to be studied, these findings suggest that the Pacific Islanders' susceptibility to hypertension arose because of human migration and adaptation.

Posterior Sloping Angle as a Predictor of Contralateral Slip in Slipped Capital Femoral Epiphysis

Slipped capital femoral epiphysis is a condition with potentially severe complications. Controversy remains as to when to undertake prophylactic pinning. We aimed to assess the utility of the posterior sloping angle as a predictor for contralateral slip in a large, multi-ethnic cohort including Polynesian children with a high incidence of slipped capital femoral epiphysis. All patients presenting to our hospital between 2000 and 2009 were identified and records were reviewed to determine demographic data and determine whether they subsequently developed a contralateral slip. The presenting radiographs were reviewed and the posterior sloping angle was measured. Patients with bilateral slips at presentation and those without initial radiographs were excluded. Records and radiographs of 132 patients were analyzed for the posterior sloping angle in the unaffected hip. Forty-two patients who had subsequently developed a contralateral slip had a mean posterior sloping angle (and standard deviation) of 17.2° ± 5.6°, which was significantly higher (p < 0.001) than that of 10.8° ± 4.2° for the ninety patients who had had a unilateral slip. Children who had developed a subsequent contralateral slip were significantly younger (11.1 years) than those who had developed a unilateral slip (12.2 years) (p < 0.001). If a posterior sloping angle of 14° were used as an indication for prophylactic fixation in this population, thirty-five (83.3%) of forty-two contralateral slips would have been prevented, and nineteen (21.1%) of ninety hips would have been pinned unnecessarily. The number needed to treat to prevent one subsequent contralateral slip is 1.79. To our knowledge, this is the largest study to date that confirms that the posterior sloping angle is a reliable predictor of contralateral slip and can be used to guide prophylactic pinning. The posterior sloping angle is applicable in the high-risk Polynesian population and could be useful in preventing future slips in populations that are difficult to follow up.

STRANGE WHAKAPAPA: COLLIDING AND COLLUDING CLAIMS TO ANCESTRY AND INDIGENEITY IN AOTEAROA

Forthcoming.

Using HLA loci to inform ancestry and health in Polynesian and Maori populations

Human leukocyte antigens (HLA) are important genetic markers of tissue identity and accurately reflect ancestral history. The work reported in this paper provides a detailed description of HLA polymorphism in Polynesian and Maori individuals in relation to other populations. Our study concerns HLA classes I and II antigens in Polynesian (N = 36) and Maori (N = 114) subjects genotyped at two digit resolution by New Zealand Blood Service Laboratory in Auckland using polymerase chain reaction-sequence specific oligonucleotide and PCR-SSP technologies. We have also compared our data with those from other Austronesian-speaking Mongoloid and Papuan-speaking Australoid populations in order to test previously published account of the origin of Proto-Polynesians via gender-biassed gene flow between these two ancestral populations. We use principal coordinate analysis for this purpose, arguing this approach to be superior to tree-based methods, because of factors associated with population history and admixture. Our data are in general agreement with earlier work and reflect received wisdom on the dual origin of Proto-Polynesians. They also show the way in which the genetic make-up of Polynesian and Maori subjects is changing due to intermarriage with Europeans.

Population Genetic Structure and Origins of Native Hawaiians in the Multiethnic Cohort Study

The population genetic structure of Native Hawaiians has yet to be comprehensively studied, and the ancestral origins of Polynesians remain in question. In this study, we utilized high-resolution genome-wide SNP data and mitochondrial genomes of 148 and 160 Native Hawaiians, respectively, to characterize their population structure of the nuclear and mitochondrial genomes, ancestral origins, and population expansion. Native Hawaiians, who self-reported full Native Hawaiian heritage, demonstrated 78% Native Hawaiian, 11.5% European, and 7.8% Asian ancestry with 99% belonging to the B4 mitochondrial haplogroup. The estimated proportions of Native Hawaiian ancestry for those who reported mixed ancestry (i.e. 75% and 50% Native Hawaiian heritage) were found to be consistent with their self-reported heritage. A significant proportion of Melanesian ancestry (mean = 32%) was estimated in 100% self-reported Native Hawaiians in an ADMIXTURE analysis of Asian, Melanesian, and Native Hawaiian populations of K = 2, where K denotes the number of ancestral populations. This notable proportion of Melanesian admixture supports the “Slow-Boat” model of migration of ancestral Polynesian populations from East Asia to the Pacific Islands. In addition, approximately 1,300 years ago a single, strong expansion of the Native Hawaiian population was estimated. By providing important insight into the underlying population structure of Native Hawaiians, this study lays the foundation for future genetic association studies of this U.S. minority population.

262P - Outcomes of Ethnic Minority Groups With Node-Positive, Non-Metastatic Breast Cancer in a Tertiary Referral Centre in Sydney

ABSTRACT Background South-Asian women in Europe are significantly younger than non-Asian at diagnosis, present with larger tumours, and have higher mastectomy rates. In Australia, there is a paucity of data on early breast cancer in ethnic minority groups. The aim of this study is to examine racial differences in tumour characteristics and outcome in early node-positive breast cancer patients at Liverpool and Macarthur Cancer Therapy Centres in New South Wales (NSW), Australia. These tertiary centres service 20% of the NSW population, with 40% from a non-English speaking background. Methods A retrospective review of patients referred to Liverpool and Macarthur with node-positive non-metastatic breast cancer diagnosed before November 2006. Variables included tumour size, number of positive nodes, histological grade, hormone receptor status, age at diagnosis, country of birth and treatment. Outcome was disease-free survival. Women of Australian/New Zealand or European backgrounds were classed as Caucasian; women from Indian sub-continent, East Asia, South-east Asia, Middle East and Polynesia were classed as Asian. The study was approved by ethics. Results There were 644 patients, with median follow up of 6.1 years. The proportion of Australian/New Zealand, European, South/East/South-east Asian, Middle-Eastern and Polynesian populations comprised 48%, 20%, 12%, 6% and 2% respectively. Women with Asian backgrounds were significantly younger at presentation (48 vs 55 years), and more likely to undergo mastectomy (46% vs 34%) and chemotherapy (82% vs 68%) than non-Asians. Tumour grade, stage and receptor status were not statistically different between the two groups. Median age, tumour size, number of nodes involved, disease-free survival and overall survival, respectively, was 52.5 years, 22mm, 2/19, 148 months and 177 months. Multivariate analysis identified risk factors of tumour size > 2cm (hazard ratio HR = 1.51, confidence interval CI 1.06-2.41, p value 0.02), > 10 lymph nodes involved (HR = 2.64, CI 1.75-3.98, p-value Conclusion Characteristics and outcome in our cohort are consistent with the literature. The Asian ethnic minority population had a younger age at diagnosis, higher mastectomy and adjuvant chemotherapy rates. Disclosure All authors have declared no conflicts of interest.

CONCORDANCE BETWEEN GENETIC AND SPECIES DIVERSITY IN CORAL REEF FISHES ACROSS THE PACIFIC OCEAN BIODIVERSITY GRADIENT

The relationship between genetic diversity and species diversity provides insights into biogeography and historic patterns of evolution and is critical for developing contemporary strategies for biodiversity conservation. Although concordant large-scale clines in genetic and species diversity have been described for terrestrial organisms, whether these parameters co-vary in marine species remains largely unknown. We examined patterns of genetic diversity for 11 coral reef fish species sampled at three locations across the Pacific Ocean species diversity gradient (Australia: ∼1600 species; New Caledonia: ∼1400 species; French Polynesia: ∼800 species). Combined genetic diversity for all 11 species paralleled the decline in species diversity from West to East, with French Polynesia exhibiting lowest total haplotype and nucleotide diversities. Haplotype diversity consistently declined toward French Polynesia in all and nucleotide diversity in the majority of species. The French Polynesian population of most species also exhibited significant genetic differentiation from populations in the West Pacific. A number of factors may have contributed to the general positive correlation between genetic and species diversity, including location and time of species origin, vicariance events, reduced gene flow with increasing isolation, and decreasing habitat area from West to East. However, isolation and habitat area, resulting in reduced population size, are likely to be the most influential.

Dusky maiden—noble savage: Pasifika representation in the NCEA drama classroom

Introduction As lens through which young people view themselves, the world and their place in the world, drama and drama texts can be powerful means of affirming or undermining positive cultural identity and self-image. Patricia Grace makes the claim that Books are Dangerous (Smith, 1999, p. 35). If books--and in the case of this article, specifically playscripts--are to be accurate representations of people, then there are particular criteria that they should fulfil: If books do not do these things, do not reinforce values, actions, customs, culture and identity, then they are dangerous ... If there are no books that tell us about ourselves but only tell us about others, then they are saying 'you do not exist' and that is dangerous ... However, if there are books that are about you and they are untrue, that is very dangerous ... If there are books about you but they are negative and insensitive so that they are saying 'you are not good', that is dangerous. (Grace, 1997, as cited in Pihama, 1994, p. 239) If people are to forge positive identity for themselves in Zealand then it follows that they must be able to relate in meaningful ways to its canon (Marsh, 2010). Critical researcher Linda Tuhiwai Smith argues that is important as concept because it gives the impression of 'the truth' (Smith, 1999, p. 35). Similarly, Marsh asks: Which books count as worth reading? Worth studying? How might these books tell us about the world, about ourselves, about how they might best be read and taught? (Marsh, 2010, p. 3). In analysing recommended playscripts for study in NCEA, this article considers and the term used in popular culture--stereotypes--and the danger that is inherent in officially and publicly accepting and affirming these in an educational setting. Definitions For the purposes of this dissertation, the definition of Pasifika as promoted by the Ministry of Education in the Education Plan 2009-2012 is used. In these terms: Pasifika is defined as a collective term used to refer to people of Pacific or ancestry who have migrated or been born in Aotearoa Zealand. include recent migrants or first, second and subsequent generations of Zealand born men, women and children of single or mixed heritage (Ministry of Education, 2011, p. 3). The term representation refers to frames of dramatic as opposed to in the form of an elected or appointed representative. However, in the context of this research we might also consider connotations of the word that imply speaking for. This is relevant as these texts have the potential to speak for all people and are representative of these same people in the Aotearoa canon of dramatic literature. The absence of voices in literature studied in schools has been concern of writers, students and scholars for some time. Dr Selina Tusitala Marsh, strong advocate for literature and critical literacy, determines that it is necessary for students to see themselves in the literary mirror of our national literatures. characters, themes and storylines are gradually becoming more visible in the literature of Aotearoa thanks to the work of scholars and writers such as Marsh, who stipulates that New Zealand is home to the largest Polynesian population in the world--Pacific Islanders constitute the fastest growing youth population, more teachers are becoming increasingly aware of the need for its taught literature to reflect this growing and dynamic demographic (Marsh, 2010, p. 3). students can participate in imaginative identification (Locke et al., 2009(2009), p. 24); the more representations there are for students to encounter, to witness, to question, to identify with, the richer their experience. Marsh writes of the aha moments that occur when students are confronted with representations of themselves and the work of the South Auckland Poets' Collective: Many were not able to read stories they could culturally identify with . …

Complete Mitochondrial Genome Sequencing Reveals Novel Haplotypes in a Polynesian Population

The high risk of metabolic disease traits in Polynesians may be partly explained by elevated prevalence of genetic variants involved in energy metabolism. The genetics of Polynesian populations has been shaped by island hoping migration events which have possibly favoured thrifty genes. The aim of this study was to sequence the mitochondrial genome in a group of Maoris in an effort to characterise genome variation in this Polynesian population for use in future disease association studies. We sequenced the complete mitochondrial genomes of 20 non-admixed Maori subjects using Affymetrix technology. DNA diversity analyses showed the Maori group exhibited reduced mitochondrial genome diversity compared to other worldwide populations, which is consistent with historical bottleneck and founder effects. Global phylogenetic analysis positioned these Maori subjects specifically within mitochondrial haplogroup - B4a1a1. Interestingly, we identified several novel variants that collectively form new and unique Maori motifs – B4a1a1c, B4a1a1a3 and B4a1a1a5. Compared to ancestral populations we observed an increased frequency of non-synonymous coding variants of several mitochondrial genes in the Maori group, which may be a result of positive selection and/or genetic drift effects. In conclusion, this study reports the first complete mitochondrial genome sequence data for a Maori population. Overall, these new data reveal novel mitochondrial genome signatures in this Polynesian population and enhance the phylogenetic picture of maternal ancestry in Oceania. The increased frequency of several mitochondrial coding variants makes them good candidates for future studies aimed at assessment of metabolic disease risk in Polynesian populations.

The Polynesian gene pool: an early contribution by Amerindians to Easter Island.

It is now generally accepted that Polynesia was first settled by peoples from southeast Asia. An alternative that eastern parts of Polynesia were first inhabited by Amerindians has found little support. There are, however, many indications of a 'prehistoric' (i.e. before Polynesia was discovered by Europeans) contact between Polynesia and the Americas, but genetic evidence of a prehistoric Amerindian contribution to the Polynesian gene pool has been lacking. We recently carried out genomic HLA (human leucocyte antigen) typing as well as typing for mitochondrial DNA (mtDNA) and Y chromosome markers of blood samples collected in 1971 and 2008 from reputedly non-admixed Easter Islanders. All individuals carried HLA alleles and mtDNA types previously found in Polynesia, and most of the males carried Y chromosome markers of Polynesian origin (a few had European Y chromosome markers), further supporting an initial Polynesian population on Easter Island. The HLA investigations revealed, however, that some individuals also carried HLA alleles which have previously almost only been found in Amerindians. We could trace the introduction of these Amerindian alleles to before the Peruvian slave trades, i.e. before the 1860s, and provide suggestive evidence that they were introduced already in prehistoric time. Our results demonstrate an early Amerindian contribution to the Polynesian gene pool on Easter Island, and illustrate the usefulness of typing for immunogenetic markers such as HLA to complement mtDNA and Y chromosome analyses in anthropological investigations.

A unique demographic history exists for the MAO-A gene in Polynesians

Variation in the human monoamine oxidase A (MAO-A) gene can influence neurotransmittor levels and is thought to have a role in many behavioral traits. The genetic architecture of MAO-A is known to vary across different geographic subgroups. Previous studies have reported evidence for positive selection within the MAO-A gene region in seven ethnic groups: Pygmy, Aboriginal Taiwanese, Chinese, Japanese, Mexican and Russian. Polynesian populations have not been tested and repeated founder effects due to the island-hopping voyages of Polynesians across the South Pacific suggest a unique demographic history exists at the MAO-A gene, perhaps including selective effects. To explore this, we genotyped 13 key single-nucleotide polymorphisms (SNPs) spanning MAO-A gene as well as the functional polymorphism (MAO-A-uVNTR) in 47 unrelated Maori individuals. A comparison of genetic variation between Maori and non-Maori groups found a substantial reduction in genetic diversity at the MAO-A gene locus and an increase in the frequency of the most common MAO-A gene variant in the Maori group. Results of this study support previous findings and also point toward a 5-SNP haplotype that may have been influenced by selective effects in the Maori population. Full-sequence data for MAO-A in a large cohort are now required to conclusively determine whether MAO-A has undergone positive selection in Polynesians. Overall, these new data describe a unique demographic history for the MAO-A gene in the Maori population and will be helpful for studies wishing to investigate MAO-A as a candidate gene for influencing behavioral traits in the Polynesians.

Ecogeographical associations between climate and human body composition: Analyses based on anthropometry and skinfolds

In the 19th century, two "ecogeographical rules" were proposed hypothesizing associations of climate with mammalian body size and proportions. Data on human body weight and relative leg length support these rules; however, it is unknown whether such associations are attributable to lean tissue (the heat-producing component) or fat (energy stores). Data on weight, height, and two skinfold thickness were obtained from the literature for 137 nonindustrialized populations, providing 145 male and 115 female individual samples. A variety of indices of adiposity and lean mass were analyzed. Preliminary analyses indicated secular increases in skinfolds in men but not women, and associations of age and height with lean mass in both sexes. Decreasing annual temperature was associated with increasing body mass index (BMI), and increasing triceps but not subscapular skinfold. After adjusting for skinfolds, decreasing temperature remained associated with increasing BMI. These results indicate that colder environments favor both greater peripheral energy stores, and greater lean mass. Contrasting results for triceps and subscapular skinfolds might be due to adaptive strategies either constraining central adiposity in cold environments to reduce cardiovascular risk, or favoring central adiposity in warmer environments to maintain energetic support of the immune system. Polynesian populations were analyzed separately and contradicted all of the climate trends, indicating support for the hypothesis that they are cold-adapted despite occupying a tropical region. It is unclear whether such associations emerge through natural selection or through trans-generational and life-course plasticity. These findings nevertheless aid understanding of the wide variability in human physique and adiposity.

Common Variants in FTO Are Not Significantly Associated with Obesity‐Related Phenotypes among Samoans of Polynesia

The association between obesity and the fat mass and obesity-associated (FTO) gene has been widely replicated among Caucasian populations. The limited number of studies assessing its significance in Asian populations has been somewhat conflicting. We performed a genetic association study of 51 tagging, genome-wide association studies, and imputed single nucleotide polymorphisms with 12 measures of adiposity and skeletal robustness in two Samoan populations of Polynesia. We included 465 and 624 unrelated American Samoan and Samoan individuals, respectively; these populations derive from a single genetic background traced to Southeast Asia and represent one sociocultural unit, although they are economically disparate with distinct environmental exposures. American Samoans were significantly larger than Samoans in all measures of obesity and most measures of skeletal robustness. In separate analyses of American Samoa and Samoa, we found a total of 36 nominal associations between FTO variants and skeletal and obesity measures. The preponderance of these nominal associations (32 of 36) was observed in the Samoan population, and predominantly with skeletal rather than fat mass measures (28 of 36). All significance disappeared, however, following corrections for multiple testing. Based on these findings, it could be surmised that FTO is not likely a major obesity locus in Polynesian populations.

Increased Y-chromosome resolution of haplogroup O suggests genetic ties between the Ami aborigines of Taiwan and the Polynesian Islands of Samoa and Tonga

The Austronesian expansion has left its fingerprint throughout two thirds of the circumference of the globe reaching the island of Madagascar in East Africa to the west and Easter Island, off the coast of Chile, to the east. To date, several theories exist to explain the current genetic distribution of Austronesian populations, with the “slow boat” model being the most widely accepted, though other conjectures ( i.e., the “express train” and “entangled bank” hypotheses) have also been widely discussed. In the current study, 158 Y chromosomes from the Polynesian archipelagos of Samoa and Tonga were typed using high resolution binary markers and compared to populations across Mainland East Asia, Taiwan, Island Southeast Asia, Melanesia and Polynesia in order to establish their patrilineal genetic relationships. Y-STR haplotypes on the C2 (M38), C2a (M208), O1a (M119), O3 (M122) and O3a2 (P201) backgrounds were utilized in an attempt to identify the differing sources of the current Y-chromosomal haplogroups present throughout Polynesia (of Melanesian and/or Asian descent). We find that, while haplogroups C2a, S and K3-P79 suggest a Melanesian component in 23%–42% of the Samoan and Tongan Y chromosomes, the majority of the paternal Polynesian gene pool exhibits ties to East Asia. In particular, the prominence of sub-haplogroup O3a2c* (P164), which has previously been observed at only minimal levels in Mainland East Asians (2.0–4.5%), in both Polynesians (ranging from 19% in Manua to 54% in Tonga) and Ami aborigines from Taiwan (37%) provides, for the first time, evidence for a genetic connection between the Polynesian populations and the Ami.

Population Heterogeneity in the Genetic Control of Serum Urate

Scanning of the genome in Caucasian cohorts for genes that control serum urate levels have revealed eight confirmed associations. Knowledge of genetic control of serum urate in other populations can be extrapolated from the study of gout, a condition of extreme hyperuricemia; three urate transport genes (SLC2A9, ABCG2, and SLC17A1/NPT1) have been studied in diverse populations (Caucasian, Asian, and Polynesian). Between-population heterogeneity is evident in allele frequency and association with gout, notably within Polynesian populations, which are defined by a geographic region and shared ancestry but also characterized by migratory events that create bottlenecks and alter genetic structure in the founder populations. Despite the large genome-wide studies in Caucasians, only 5% of the variance in serum urate levels has been explained. A more complete picture will be revealed by very large meta-analyses of genome-wide association scans in Caucasian and in other populations with less genetic heterogeneity than Caucasians.

Letters to the Editors: High frequency of MCM6 lactose intolerance genotype in Polynesian People: authors’ reply

self-identified M aori or Pacific Islanders, has led us to hypothesize that modern Polynesian populations will have a high frequency of the lactose intolerant genotype MCM6 -13910C ⁄C. The aim of this study was to conduct the first investigation of MCM6 in Polynesians. Each participant gave their informed consent and approval for the study was obtained from the Lower South Regional Ethics Committee (New Zealand). One hundred and sixty-one individuals with self-reported M aori and ⁄or Pacific Island-ancestry were genotyped for MCM6 rs4988235 using a custom-designed TaqMan SNP assay (Applied Biosystems, Foster City, CA, USA). MCM6 13910C>T allele and genotype frequencies, stratified by self-reported ethnicity, are shown in Table 1. MCM6 -13910C ⁄C frequency was the lowest in individuals who were >0.50 Caucasian and rose significantly with increasing Polynesian ancestry (P < 0.0001). This study, which found 34% of participants had the MCM6 -13910C ⁄C genotype, suggests that lactose intolerance is very common in M aori and Pacific Island communities. In New Zealand, 53% of dietary calcium comes from consumption of dairy products and 30–35% of M aori females have intakes below the recommended daily intake. The avoidance of milk by M aori and Pacific Island people could significantly increase their risk of calcium deficiency and osteoporosis.

Inheritance of a novel mutated allele of the OCA2 gene associated with high incidence of oculocutaneous albinism in a Polynesian community

Oculocutaneous albinism type 2 (OCA2) is a human autosomal-recessive hypopigmentation disorder associated with pathological mutations of the OCA2 gene. In this study, we investigated a form of OCA in a Polynesian population with an observed phenotype characterized by fair skin, some brown nevi present in the sun-exposed areas and green or blue eyes. Hair presented with a unique red coloration since birth, with tones ranging across individuals from Yellow-Red to Brown-Red, or Auburn. We genetically screened for mutations in the OCA2 and MC1R genes as their products have previously been shown to be associated with red hair/fair skin and OCA2. The SLC45A2 gene was also screened to identify any possible relation to skin color variation. We have identified a novel missense substitution in the OCA2 gene (Gly775Asp) responsible for OCA2 in individuals of Polynesian heritage from Tuvalu. The estimated incidence of this form of OCA2 in the primary study community is believed to occur at one of the highest recorded rates of albinism at approximately 1 per 669 individuals. In addition, we have analyzed four unrelated individuals with albinism who have Polynesian heritage from three other separate communities and found they carry the same OCA2 mutation. We also analyzed an out-group comprising three unrelated individuals with albinism of Melanesian ancestries from two separate communities, one Australian Aboriginal and three Australian Caucasians, and did not detect this mutation. We hypothesize that this mutation may be Polynesian specific and that it originated from a common founder.

Plunging ranulas: high-resolution ultrasound for diagnosis and surgical management

We see a high incidence of plunging ranulas, particularly in Maori and Polynesian populations. We have investigated the usefulness of ultrasound in the diagnosis and management of plunging ranulas and present our findings. Thirty-three new cases were examined over 4 years (June 2004 to October 2008). High-resolution ultrasound was very successful in determining the extent of the plunging ranula, confirming the cystic nature of the lesion, assessing the status of the mylohyoid muscle (a defect demonstrated in 100% of our cases) and evaluating the sublingual gland for rupture or herniation. Correlation with surgical findings was available for 30 cases. There was excellent ultrasonographic and surgical correlation, particularly with respect to submandibular space cystic collection (29 of 30 cases, 96.7%) and mylohyoid defects (27 of 30 cases, 90%). With the considerations of cost, accessibility and the fact that many of our patients are young (median of 20 years), ultrasound is recommended as the preferred examination for plunging ranula.