Blood groups and other genetic markers in New Zealand Europeans and Maoris

Molecular approaches to transfusion medicine in Polynesians and Maori in New Zealand

In recent years, with the application of genotyping technology, there has been a substantial increase in the number of reported blood group alleles. This survey was designed to evaluate new molecular blood group genotyping methods and compile reference blood group data sets for Polynesian and Maori subjects. Subsequent analyses of these results were used to calculate probability of random match, to trace Polynesian ancestry and migration patterns and to reveal past and present episodes of genetic admixture. Genomic DNA samples from Maori and Polynesian subjects were drawn from the Victoria University of Wellington DNA Bank and genotyped using combination of commercial PCR-SSP kits, hybridization SNP assay services or sequence-based typing. This survey also involves compilation of serological ABO and Rhesus blood group data from RakaiPaaka Iwi tribal members for comparison with those generated during our molecular blood group study. We observed perfect consistency between results obtained from all molecular methods for blood group genotyping. The A, O, DCcEe, DCCee, MNs, K-k+, Jk(a+b-), Jk(a+b+), Fy(a+b-), Fy(a+b+), Di(a+b-), Co(a+b-) and Do(a-b+) were predominant blood group phenotypes in both Polynesians and Maori. Overall, our survey data show only small differences in distributions of blood group phenotypes between Polynesian and Maori groups and their subgroups. These differences might be associated with selection, population history and gene flow from Europeans. In each case, we estimate that patients with certain blood groups have a very low probability of an exact phenotypic match, even if the patients were randomly transfused with blood from donors of their own ethnicity. The best way to avoid haemolytic transfusion reaction in such cases is to perform a pretransfusion cross-match and recruit increased numbers of donors with rare phenotype profiles. The conclusion of this study is that application of molecular method covering as many known variants as possible may help to improve the accuracy blood group genotyping and potentially conserve the routine requirements of transfusion centres.

The genetic affinity of Polynesians: evidence from Y chromosome polymorphisms

Y-linked polymorphisms were studied in a sample of 60 Polynesians, and results were compared with findings from studies on other major population groups. Three previously unreported 49a/TaqI haplotypes were observed, two of which possess a new polymorphic fragment named I2. Frequency data for the 49a/TaqI, XY275, pDP31 and Y Alu polymorphisms indicate that Polynesians have greater affinity to Caucasoids than to African populations. Similar population frequency trends were not observed for the p21A1/TaqI polymorphism, supporting the hypothesis that this polymorphism has arisen more than once.

T cell receptor polymorphisms in Caucasians and Polynesians

The purpose of this study was to find genetic polymorphisms that might be useful in studies of Polynesian-Caucasian racial admixture and Polynesian disease susceptibility. The allele frequencies of six T cell receptor locus RFLP were measured in 73 Caucasians and two Polynesian ethnic groups comprising 86 Maoris and 95 Samoans. The RFLP studied were (locus/enzyme/probe): C alpha/Taq1/Y14, V alpha/Taq1/Y14, C beta/BglII/Y35, C gamma/Pvu II/HGP02, V beta 7/BamHI/V beta 7.4 and V beta 8/Bam HI/V beta 8.1. Racial differences in allele frequency were present with all six RFLP (P < 0.001). The allele frequencies of the V alpha/Taq1/Y14 and the V beta 7/BamHI/7.4 RFLP were similar in the two Polynesian groups, both of which differed from the Caucasians. The 1.4 kb allele of the V alpha/Taq1/Y14 RFLP and the 8.0 kb allele of the V beta 7/BamHI/7.4 RFLP were present in low frequency in both Polynesian groups compared to the Caucasian group, consistent with a gene flow effect. These alleles may be useful in studies of Caucasian-Polynesian racial admixture.

Genetic polymorphisms in the white population of Victoria, Australia

Genetic variation in the rural population of the State of Victoria, Australia, is demonstrated through the analysis of eight genetically independent red cell antigen, red cell enzyme and plasma protein systems in a sample of more than 2000 blood donors. The polymorphisms investigated were ABO, RH, KEL, esterase D (ESD), glyoxalase 1 (GLO1), phosphoglucomutase locus 1 (PGM1), haptoglobin (HP) and the third component of complement (C3). For genetic distance analysis the sample was subdivided into nine regions using the Victorian Government's Statistical Divisions. Considerable regional genetic heterogeneity exists; with the Goulburn and the Central Highlands divisions being the most distinct, not only from the other seven divisions, but also from each other. The pattern of micro-differentiation is complex and cannot be easily explained, but there is evidence of varying levels of systematic evolutionary pressure on the Victorian divisions. The investigation of the proportion born overseas in each division, and their respective countries of origin, did not help in the interpretation of the findings. Overall, rural Victorians exhibited allele frequencies very similar to the populations of both Melbourne, the Victorian capital, and the island State of Tasmania.

Racial inequalities in childhood asthma

Mortality and hospital admission rates for asthma are higher in Maoris and Pacific Islander children than in European children. These ethnic differences are not explained by ethnic differences in asthma prevalence, the characteristics of the disease or admission criteria. There are major ethnic differences in asthma drug management both in the community and at the time of discharge from hospital. In particular Polynesians were less likely to receive prophylactic therapy and this factor probably accounts for ethnic differences in mortality and admission rates. Possible explanations for the ethnic differences in medical management are discussed.

Prediction of possibly preventable death: a case-control study of postneonatal mortality in southern New Zealand

The postneonatal mortality rate in three southern regions of New Zealand was 8.1 per 1000 live births for 1979-1984. The possibly preventable postneonatal mortality rate was 7.1 per 1000 live births and data on 377 possibly preventable deaths and 936 randomly selected controls were used to develop a two-stage risk-scoring system. Logistic regression analysis was undertaken separately on two sub-samples of the total sample. The data were used to evaluate three other previously published scoring systems. The four variables used in our birth score (mother's age, parity, marital status, and birth weight) have all appeared in other scoring systems, and this score could identify a group of infants in southern New Zealand with an estimated 1.7% mortality rate in the first year of life. It is suggested that currently the only valid use of risk-scoring in this region is for the definition of a high-risk population for the purpose of evaluating potential intervention strategies.