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Biomedical subjects

N G White

Publications and source records attributed to N G White.

16 recordsLinked to original sources
PubMed2002

Alleles and haplotypes of tumor necrosis factor (TNF) alpha and beta genes in three ethnic populations of Sulawesi Indonesia.

Polymorphic variation in two cytokine genes, tumor necrosis factor (TNF) -alpha and -beta, was examined in three ethnic groups, the Bugis, the Makassans, and the Torajans, who inhabit Sulawesi, a large island in the Indonesian archipelago, and formerly a Dutch colony. TNF-alpha and -beta are key molecules in immune responses to infection, and both have been implicated in the pathogenesis and clinical manifestations of parasitic diseases. Several polymorphic variants with the potential to affect cytokine levels in autoimmune diseases and parasitic and bacterial infection have been reported. Two loci in the promoter region of TNF-alpha and two sites in the first intron of TNF-beta were scored in a maximum of 150 Bugis, 168 Makassans, and 58 Torajans. Genotypes at the two TNF-alpha loci are not in Hardy-Weinberg equilibrium because of a deficit of heterozygotes (p < 0.05). However, genotypes at the TNF-beta loci exhibit Hardy-Weinberg equilibrium. A comparison of allelic and genotypic frequencies at all TNF loci across the ethnic groups reveals that the differences are significant for TNFalpha(308) (p < 0.01) and for TNFbeta(NcoI) (p < 0.05). Overall, the distribution of the alleles differs from that seen in the few Asian populations for which data are available (p < 0.05). Construction of 4-locus haplotypes showed that, in addition to the five previously reported, four novel haplotypes were present in Sulawesi. These novel haplotypes were in low frequency, and two were seen only in Bugis (haplotypes F and J) and one (haplotype K) only in Makassans. The other, haplotype D, was present in Makassans and Torajans. Preliminary sampling of other ethnic groups suggests that three of these haplotypes (D, F, and J) may be restricted to Asian or Asian-derived populations. The frequency of the common TNF haplotypes differed between Dutch and Sulawesi populations, and these data also indicated that haplotype E, which has a relatively high frequency in the Dutch (25%), may be a useful marker of Dutch/European admixture in Indonesian populations, in which it is either rare (1%) or absent. The results suggest that unique allelic combinations with potential to influence cytokine secretion are present in Sulawesi, possibly as a consequence of parasite-driven selection, and argue for more extensive investigation of haplotype distribution in parasite-endemic areas.

Alleles↗
PubMed2000

Distribution of the 3' VNTR polymorphism in the human dopamine transporter gene in world populations.

A polymorphism with a variable number of tandem repeats (VNTR) found in the 3' untranslated region of the human dopamine transporter gene (DAT1) was scored in unrelated individuals drawn from 10 geographically widely dispersed populations in order to assess this marker's usefulness in human population genetics. The populations that were analyzed in this study included 4 indigenous groups of Siberia, natives of North and South America, as well as Caucasian and Oceanic groups, most of which represented small-scale societies. A total of 5 DAT1 alleles were seen overall, but only in one Siberian population, the Altai-Kizhi, were all 5 present, and in the Native Americans of Colombia the locus was monomorphic. The most common allele, DAT1*10, ranged in frequency from 52% in Greeks to 100% in South Americans. The high frequency of the DAT1*10 allele (approximately 90%) among Mongoloid groups of north and east Asia distinguishes them from most Caucasian groups. The presence of the rare DAT1*7 allele in relatively high frequency (approximately 5%) among all Siberian groups suggests a close affinity with north Asian groups, especially Mongolians. The presence of the even rarer DAT1*13 allele in one Siberian population, the Altai-Kizhi, reflects this group's long historical contact with Mongolians. The results demonstrated that the DAT1 VNTR polymorphism is useful in investigating population relationships, and that rare alleles at this locus may be particularly valuable in understanding the extent of genetic affinity between neighboring groups and in situations where admixture is suspected. However, because of both the association and linkage of this VNTR locus with attention-deficit hyperactivity disorder (ADHD) in children, and its highly restricted polymorphism (usually 3 alleles) in most human groups, the possibility of selection constraints on the DAT1 gene cannot be ignored.

Female↗
PubMed1999

Deletion polymorphism in the human COL1A2 gene: genetic evidence of a non-African population whose descendants spread to all continents.

We report the frequencies of a deletion polymorphism at the alpha 2 (1) collagen gene (COL1A2) and argue that this distribution has major implications for understanding the evolution of modern humans immediately after their exodus from sub-Saharan Africa as well as their subsequent spread to all continents. The high frequency of the deletion in non-African populations and its complete absence in sub-Saharan African groups suggest that the deletion event occurred just before or shortly after modern humans left Africa. The deletion probably arose shortly after the African exodus in a group whose descendants were among the ancestors of all contemporary populations, except for sub-Saharan Africans. This, of course, does not imply that there was a single migration out of Africa. The GM immunoglobulin haplotype GM*A,X G displays a similar distribution to that for the COL1A2 deletion, and these 2 polymorphisms suggest that the exodus from Africa may not have been a rapid dispersion to all other regions of the world. Instead, it may have involved a period of time for the savanna-derived gene pool to adapt to novel selective agents, such as bacteria, viruses, and/or environmental xenobiotics found in both animal and plant foods in their new environment. In this context these polymorphisms are indicators of the evolution that occurred before the diaspora of these populations to the current distribution of modern peoples.

Africa South of the Sahara↗
PubMed1988

An investigation of nutrition-related risk factors in an isolated Aboriginal community in northern Australia: advantages of a traditionally-orientated life-style.

Australian Aborigines develop a high frequency of type-2 diabetes mellitus when they make the transition from a traditional to an urban life-style. Preliminary studies were conducted at an outstation in northeastern Arnhem Land where the Aborigines have been exposed to Western influence for approximately 20 years only and where they continue to follow a life-style that is largely traditional. At the time of the study 31 persons were resident at the outstation, 20 persons were over 15 years of age (adults) and 11 persons were under 15 years of age (children). Eighteen adults and six children were tested. By standard criteria for body mass index these persons were all underweight (less than 20 kg/m2). In spite of this, they displayed no biochemical evidence of malnutrition. Their plasma fatty-acid profiles were consistent with a low dietary fat intake and a high consumption of lean meat. Levels of linoleic acid were much lower and those of arachidonic acid were much higher than are those in persons who consume a Western diet. Fasting glucose and cholesterol concentrations were low relative to those of urbanized Aborigines and white Australians. However, their fasting insulin and triglyceride levels were inappropriately high for their very low body mass index and fasting glucose levels. The mild elevation of triglyceride and fasting insulin levels is consistent with insulin resistance and suggests that these Aborigines (in common with other Aborigines) may become susceptible to obesity and diabetes if they became urbanized further.

Adolescent↗
PubMedDate not supplied

Anthropometry, lifestyles and fat patterning in Balinese women.

BACKGROUND: In many parts of the developing world, modernization has resulted in an increase in the prevalence of overweight and obesity and a subsequent rise in nutrition-related, non-communicable diseases such as cardiovascular disease and Type 2 diabetes. AIM: The study examined the impact of socio-economic and lifestyle changes associated with modernization on the body size and shape of Balinese women. SUBJECTS AND METHODS: Anthropometric data including weight, height, body mass index (BMI) and seven skinfolds were collected from 564 Balinese women, aged between 15 and 45 years. The relationship between the degree of 'modernization' (using such parameters as household wealth and education level) and body size and shape was analysed using multiple regression analysis, as was the effect of age, family size and breast-feeding. RESULTS: Using the WHO (WHO 1995) categories of BMI, 14% of Balinese women displayed Chronic Energy Deficiency (BMI < 18.5 kg m(-2)), 7% were overweight (BMI = 25.0-29.9 kg m(-2)) and less than 1% were obese (BMI > or = 30.0 kg m(-2)). Household wealth (p < 0.0001) and education level (p < 0.05) were significantly associated with fatness, while breast-feeding (p < 0.05) was significantly associated with leanness. Fat distribution was largely independent of biological and socio-economic variables. CONCLUSIONS: The trend toward increasing fatness associated with greater household wealth and higher education has important health implications for Balinese women as they continue their rapid transition from subsistence agriculture towards a more 'western' lifestyle.

Adipose Tissue↗
PubMedDate not supplied

Adiposity in aboriginal people from Arnhem Land, Australia: variation in degree and distribution associated with age, sex and lifestyle.

A number of researchers have found substantial sex, population and group differences in adiposity and fat-distribution patterns, but there is relatively little information on body fat distribution in Aboriginal groups, especially for the indigenous people of Australia. This study, the largest of its kind for Australian Aboriginal people, presents information on adiposity and fat distribution in 425 Yolngu, a group of Aboriginal people living in a number of communities representing a wide range of lifestyles, in northeast Arnhem Land, Australia. Using BMI standards developed for people of European descent, the majority of the individuals in this study were lean, and the incidence of obesity was considerably less than in other Australian groups, Aboriginal and non-Aboriginal. For the Yolngu in this study the relationship between ageing and adiposity is similar to that reported for tradition-orientated Aboriginal people, as well as for a number of other indigenous groups, viz., while the men maintain their weight into old age, the women, once they are past early adulthood, lose body fat with age. The results from the present study suggest that the age at which the Yolngu women start to gain, and subsequently lose, body fat is associated with differences in degree of acculturation. As has been found in other populations, age- and sex-related differences in body fat distribution occur, but no correlation was found between adiposity and fat distribution. The Aboriginal women and men, however, had a significantly more central distribution of subcutaneous fat than their non-Aboriginal counterparts. Our findings have implications for the health and demography of Aboriginal people in general, and the Yolngu in particular, as they continue the transition from hunting and foraging towards a more 'westernized' lifestyle.

Adipose Tissue↗