Indigenous African Population Research Articles

Waist-hip ratio and breast cancer risk in urbanized Nigerian women.

The aim of this study was to examine the relationship between waist-hip ratio and the risk of breast cancer in an urban Nigerian population. Between March 1998 and August 2000, we conducted a case-control study of hospital-based breast cancer patients (n = 234) and population-based controls (n = 273) using nurse interviewers in urban Southwestern Nigeria. Multivariable logistic regression showed a significant association between the highest tertile of waist-hip ratio and the risk of breast cancer (odds ratio= 2.67, 95% confidence interval = 1.05-6.80) among postmenopausal women. No association was found in premenopausal women. The present study, the first in an indigenous African population, supports other studies that have shown a positive association between obesity and breast cancer risk among postmenopausal women.

HLA-G exhibits low level of polymorphism in indigenous East Africans

Human leukocyte antigen G (HLA-G) is a nonclassical HLA class I antigen that is predominantly expressed on invasive cytotrophoblastic cells, and is postulated to be a mediator of maternal-fetal tolerance. Almost all studies in Caucasian and Asian populations have consistently reported that HLA-G exhibits low levels of allelic polymorphism unlike the classical class I genes. However, the concept that HLA-G is nonpolymorphic has recently been challenged in a single study of African-American subjects. We have examined the DNA sequences of the first seven HLA-G exons by single-strand conformational polymorphism (SSCP) and DNA direct sequencing procedures in 45 healthy individuals from an indigenous African population. Overall, we detected 14 sequence variations: 3 in the signal peptide (exon 1); 2 in the α-1 domain (exon 2); 5 in the α-2 domain (exon 3); 2 in α-3 domain (exon 4); 2 in transmembrane domain (exon 5); and none in the cytoplasmic tail (exons 6 and 7). Of these variants, only three result in amino acid substitutions at the protein level. Of particular interest, we identified a novel nucleotide substitution (C727T), 56 bp before the HLA-G gene transcription start site, located in the putative binding site for polyomavirus enhancer-binding protein 2 (PEBP2) transcriptor factor. These data confirm previous reports describing HLA-G exhibiting limited allelic polymorphism. Further studies are needed to determine the impact of the C727T polymorphism on the level or developmental regulation of HLA-G expression.

People's English, codification, function, and logic

A response to Pearl Ntlhakana, ‘People's English’, on the language situation in South Africa, in ET62 (16:2), Apr 2000.If you have a non-standard local form of English, what do you do with it?Pearl Ntlhakana gives a bold answer, supporting her arguments by reference to an article by Chick and Wade (1997), also on the South African situation. By “People's English”, Ntlhakana means what is usually referred to as Black South African English (BSAE), the English that is said to be characteristic of the indigenous African population of South Africa. What she suggests is that “a restandardised variety would actually replace the current standard (White South African English with Southern British English as its model), performing the whole range of formal functions”.

A review of taurodontism with new data on indigenous southern African populations

The prevalence and degree of taurodontism (enlargement of the pulp cavity) in the mandibular permanent molars of two recent population samples from southern Africa were investigated quantitatively from lateral radiographs. The degree of occlusal wear was scored and two measures of relative pulp cavity size were recorded for each tooth. There was a significant association between increased attrition and a reduction in the size of the pulp cavity when all of the teeth were considered together, but no correlation among individual molar types within each sample. In both the Zulu ( n=68 individuals) and Khoisan ( n=28 individuals) samples, third molars had the highest prevalence of taurodontism and first molars the lowest. The data for Zulus are similar to those recorded for other modern populations (e.g. white and black Americans, and Israelis), whereas the Khoisan data exhibit significantly higher frequencies. An increased appreciation of the distribution of this variant in modern human populations would contribute to an understanding of its possible evolutionary significance in the human fossil record.

HLA-G and HLA-E polymorphisms in an indigenous African population

Studies of HLA-G and HLA-E polymorphisms in different populations from many industrialized countries have uniformly reported little sequence variation within these genes. To date, the polymorphism of these genes has not been characterized in populations from developing countries where more sequence variation would be anticipated due to greater exposure to microbial pathogens. In order to address this issue, we have recently investigated the polymorphism of these MHC genes in an indigenous African population (Shona ethnic group). HLA-G and HLA-E alleles were determined by PCR-restriction fragment length polymorphism (PCR-RFLP) and amplification refractory mutation system (ARMS) analysis in 108 unrelated women recruited from maternity clinics and hospitals in Harare (Zimbabwe). The genotyping analysis identified six different HLA-G alleles and three HLA-E alleles in this population. Of interest, the null-allele HLA-G∗0105N was found with 11.1% of frequency, which is higher than in other populations tested so far. We observed the presence of 15 distinct HLA-G genotypes and 6 HLA-E genotypes. These data indicate that this African population contains low levels of allelic polymorphism similar to ethnic groups from industrialized countries. This is the first report describing HLA-G and HLA-E polymorphisms in an indigenous African population.

Geographic distribution and frequency of a taurine Bos taurus and an indicine Bos indicus Y specific allele amongst sub‐Saharan African cattle breeds

We report for the first time, and for the whole of sub-Saharan Africa, the geographical distribution and the frequency of an indicine and a taurine Y specific allele amongst African cattle breeds. A total of 984 males from 69 indigenous African populations from 22 countries were analysed at the microsatellite locus INRA 124. The taurine allele is probably the oldest one on the continent. However, the taurine and the indicine alleles were present in 291 males (30%), and 693 males (70%), respectively. More particularly, 96% of zebu males (n = 470), 50% of taurine males (n = 263), 29% of sanga males (crossbreed Bos taurus x Bos indicus, n = 263) and 95% of zebu x sanga crossbred males (n = 56) had the indicine allele. The Borgou, a breed classified as zebu x taurine cross showed only the zebu allele (n = 12). The indicine allele dominates today in the Abyssinian region, a large part of the Lake Victoria region and the sahelian belt of West Africa. All the sanga males (n = 64) but only one from the Abyssinian region had the indicine allele. The taurine allele is the commonest only among the sanga breeds of the southern African region and the trypanotolerant taurine breeds of West Africa. In West Africa and in the southern Africa regions, zones of introgression were detected with breeds showing both Y chromosome alleles. Our data also reveal a pattern of male zebu introgression in Mozambique and Zimbabwe, probably originating from the Mozambique coast. The sanga cattle from the Lake Victoria region and the Kuri cattle of Lake Chad, cattle populations surrounded by zebu breeds were, surprisingly, completely devoid of the indicine allele. Human migration, phenotypic preferences by the pastoralists, adaptation to specific habitats and to specific diseases are the main factors explaining the present-day distribution of the alleles in sub-Saharan Africa.

Founder mutations in the LDL receptor gene contribute significantly to the familial hypercholesterolemia phenotype in the indigenous South African population of mixed ancestry.

The South African population harbors genes that are derived from varying degrees of admixture between indigenous groups and immigrants from Europe and the East. This study represents the first direct mutation-based attempt to determine the impact of admixture from other gene pools on the familial hypercholesterolemia (FH) phenotype in the recently founded Coloured population of South Africa, a people of mixed ancestry. A cohort of 236 apparently unrelated patients with clinical features of FH was screened for a common mutation causing familial defective apolipoprotein B-100 (FDB) and seven low-density lipoprotein receptor (LDLR) gene defects known to be relatively common in South Africans with FH. Six founder-type 'South African mutations' were responsible for FH in approximately 20% of the study population, while only 1 patient tested positive for the familial defective apolipoprotein B-100 mutation R3500Q. The detection of multiple founder-type LDLR gene mutations originating from European, Indian and Jewish populations provides direct genetic evidence that Caucasoid admixture contributes significantly to the apparently high prevalence of FH in South African patients of mixed ancestry. This study contributes to our knowledge of the biological history of this unique population and illustrates the potential consequences of recent admixture in populations with different disease risks.

The age of onset and sex distribution of insulin-dependent diabetes mellitus in Africans in South Africa.

Type I (insulin-dependent) diabetes mellitus (IDDM) appears to be rare in indigenous African populations, but little detailed information has been published. We have therefore analysed the age of onset of diabetes in 176 African patients with IDDM (age of onset < 35 years), and in 149 consecutive white patients of European extraction for comparison. In the Africans the peak age of onset occurred at 22-23 years (median 22 years) with an earlier peak from 14 to 17 years. In the Whites, the peak was found at 12-13 years (median 12 years). In only 7% of Africans did diabetes start under the age of 12 years. There was a slight female preponderance in the Africans, especially at the ages of greatest incident (20-25 years)-F:M 1.55:1. When patients with duration of diabetes less than 5 years only were analysed (the period during which early mortality among African patients was greatly reduced) the patterns of age distribution were similar to the total respective groups. A peak incidence in the winter months was noted.

Serum retinol, carotenoids, vitamin E, and cholesterol in Nigerian women

An epidemiologic study was conducted to assess serum levels of retinol, carotenoids, vitamin E, and their associations with cholesterol in an indigenous African population. The study population consisted of 116 black Nigerian women representing a response rate of 74%. The ages ranged from 17–32 years with a mean age of 22.6 years. The beta-carotene, total carotenoids, alpha-tocopherol, and cholesterol levels for the Nigerian women were 3.93 μmol/L, 7.03 μmol/L, 18.78 μmol/L, and 4.01 mmol/L, respectively. The beta-carotene levels of the Nigerian women ranged from 1.2–13 times greater than the United States population, and the total carotenoid levels were 2.5 times greater in the Nigerians compared with the United States population. On the contrary, the cholesterol levels of the Nigerians ranged from 5%–24% lower than similarly aged United States populations. Significant positive associations were observed between cholesterol and the following: 1) beta-carotene ( r = 0.31, P < 0.001): 2) total carotenoids ( r = 0.43, P < 0.001); and alpha-tocopherol ( r = 0.72, P < 0.001). The findings suggest that dietary intake may not be the key factor in the vitamin A-cholesterol relationship, because this relationship has been observed in populations with significantly lower vitamin A and higher saturated fat intake.

Definition of the HLA-Aw43 antigen.

The HLA antigen Aw43 has been observed only in Southern African populations. In order to confirm its identity and clarify its definition, ten cells with this specificity were shipped to laboratories in England, the United States of America and Australia to be tested with the sera from the 10th International Histocompatibility Workshop. The results of tests on nine of these cells which were sufficiently viable indicated that HLA-Aw43 is a distinct serological specificity which could be distinguished from both the A10 cross-reacting group (A25, A26 and Aw34) and A29. The Aw43 specificity segregated in two South African Negro families, and occurred commonly in association with Bw70. The occurrence of HLA-Aw43 in South African Caucasoids, in contrast to its absence in other Caucasoid groups, is probably due to genetic admixture with indigenous South African populations.

The Incidence and Pattern of Atherosclerosis in Africans

Despite the very high incidence of arterial hypertension among Africans ath erosclerotic changes linked with prolonged hypertension is not commonly en countered and even then the coronary arteries are known to be spared. Since this seeming protection against atherosclerosis is said to be found among Afri can populations we carried out a study to ascertain the current presentation and pattern of atherosclerosis including fatty streaking of the intima in an indige nous African population. Our findings show that atheroma as a degenerative disease (not linked with hypertension), contrary to prevailing opinion, is not uncommon among Africans. However, the incidence and pattern of distribution of the lesion especially in the aorta show features which indicate interesting peculiarities in the population studied. We also found that although fatty streak ing of the intima was common and had its peak incidence in the third decade of life, comparatively fewer cases later progressed to atheroma formation.

Developmental mutants isolated from wild-caught Xenopus laevis by gynogenesis and inbreeding.

Xenopus laevis obtained from indigenous African populations are a rich source of mutants affecting development. Gynogenesis and inbreeding were used to isolate mutants affecting development from wild-caught Xenopus laevis females. Fourteen mutants were recovered from eight females tested. One mutant was recovered from each of two females. This load of 1.875 developmental mutants per female is similar to that found in the axolotl (Ambystoma mexicanum), a urodele amphibian, and is only slightly less than the load of mutants with major developmental effects found in Drosophila and man. These results suggest that the anuran amphibian Xenopus laevis, an ancestrally tetraploid species, has undergone extensive diploidization of developmentally important loci and that gynogenesis and inbreeding of wild-caught animals can provide adequate mutants at diploid loci for developmental genetic studies.

Behavior therapy in South Africa: A review

Behavior therapy in South Africa has, after strong beginnings, undergone a slump which seems largely due to the drain of leading behavior therapists from this country. During the last decade there has been evidence of a revival of this approach, due largely to the increasing place of behavior therapy in clinical training curricula. Questionnaire and interview data from universities and hospitals indicated that therapy training was “eclectic” in the sense that interns and registrars were expected to master the basics of several approaches; and this was reflected in clinical practice in that most therapists used behavior therapy in conjunction with other approaches. It was noted that relatively little research in behavior therapy was published by South Africans, but that this appeared to be increasing in the last few years. Cross-cultural issues were assuming increasing importance as psychotherapeutic services were increasingly extended to the indigenous African population of this country, and it was suggested that behavior therapy was an effective approach in this context when due consideration was given to the cultural beliefs and patterns of the particular patient.

Edward Blyden: Liberian Independence and African Nationalism, 1903-1909

BY THE FIRST YEARS of the twentieth century, black people found themselves almost everywhere under white rule. One of the few exceptions was in Liberia, where black immigrants from the Western Hemisphere governed an indigenous African population. However, about this time Liberia's independence was threatened as well, and a debate ensued over Liberia's role and future that sheds some light on the subsequent development of African nationalism. One of the central figures in these events and this debate was an immigrant to Liberia from the West Indies, Edward Wilmot Blyden. He was by any account Liberia's most renowned intellectual and diplomat at the turn of the century. During his long career he had written numerous books and articles on African culture and history. He had served twice as Liberian Secretary of State, and also as Liberian Minister to England and France, President of Liberia College and Secretary of the Interior. Further, he had toured the United States and the West Indies frequently to encourage black emigration to Liberia.' Despite this illustrious background, he frequently found himself in disrepute and actual danger in Liberia, even to the point of being forced several times into exile.2 Blyden's unorthodox, for the times, racial attitudes and cultural concepts were the reason. His intellectual theses, as outlined and detailed in almost fifty books, articles and pamphlets, dealt primarily with what he saw as the essence and mission of African culture. Blyden insisted on the equality and the uniqueness of black people. He felt they should not waste time mimicking Europeans or competing with them in the areas of science or politics, but that Africans should concentrate on perfecting their special gifts in the fields of morality and social organization. For these ideas, Blyden has been called the father of African nationalism.3 However, these ideas were unattractive to the Westernized AmericoLiberians who controlled affairs in Liberia. These people were proud of their civilization, and felt it distinguished them from indigenous Africans.4 Many of the disputes between Blyden and the Americo-Liberians centered on their relations with the much larger African nations that inhabited most of Liberia. Blyden felt the Americo-Liberians had to amalgamate with the Africans if Liberia was ever to amount to any-

Hb Bart's and its significance in the South African Negro.

The haematological indices of cord bloods from 430 South African Negro babies were determined by electronic cell counting and their haemoglobin (Hb) patterns examined by alkaline cellulose acetate electrophoresis. A fast-moving, anodal band, identified as Hb Bart's, was found in 7 (1,6%) of the specimens, this being the lowest incidence of the variant yet found in an indigenous African population. The levels of Hb Bart's ranged from 1.3 to 5.5% of the haemoglobin. These findings were confirmed by alkaline-starch gel electrophoresis and at the same time absence of the slow-moving haemoglobin, Hb Constant Spring was established. Subsequent follow-up of 4 of the infants at 4 months of postnatal life showed that the abnormal component had disappeared. The babies with Hb Bart's had a marked microcytosis and low mean corpuscular haemoglobin levels whilst their parents showed no haematological or electrophoretic signs of alpha-thalassaemia. The significance of these findings is discussed in the light of previously reported studies on various Negro groups.

New and Old Agents in Diarrhea: a Prospective Study of an Indigenous Adult African Population *

We conducted a prospective study 77 indigenous African adults with acute diarrhea seeking care at the major hospital in Nairobi, Kenya, to determine the major pathogens responsible for this syndrome in adults. Fecal and blood specimens were collected and examined for enteric bacterial pathogens, viruses, and parasites. In 13 (26%) inpatients and 11 (49%) outpatients Shigella was found, and heat-labile and heat-stable forms of enterotoxigenic Escherichia coli were found in 9 (18%) inpatients and 1 (4%) outpatient. Human revirus-like agent titers rose significantly in another 3 (6%). Amebic dysentery was not seen although hemagglutination-inhibition tests for invasive Entamoeba histolytica were positive in 4 inpatients. An etiologic agent was found in 65% of patients.

Polymgamy and genetic equilibrium.

POLYGAMY is the normal practice in indigenous African and Islamic populations. Recently Konotey-Ahulu1 has claimed that polygamy may explain the persistence of some abnormal haemoglobins in these populations. The generally accepted view is that the maintenance of balanced polymorphism in these populations at the loci of the commonest hereditary erythrocyte defects is due to a lesser susceptibility of the heterozygote2–7. An examination of that claim using a mathematical model shows that polygamy can lead to an equilibrium distribution in gene frequencies only if the male heterozygote tends to acquire more wives than either homozygote—a condition that is shown not to be unlikely in African and Islamic populations.

The effects of sex and age on serum IgE concentrations in three ethnic groups.

Serum IgE concentrations were measured using a radio-radial immunodiffusion method in 4,440 blood donors resident in the Western Cape Province, South Africa, and the following differences were observed. Firstly, in all three ethnic groups studied, that is the Whites, the Cape Coloureds and the Africans, there was a tendency for males to have higher serum IgE concentrations than females. This differences was highly significantly in Whites. Secondly, in the Whites, serum IgE concentrations tended to be lower with advancing age. Thirdly, previous reports of elevated serum IgE concentration in indigenous African population were confirmed. No clearly defined cause for these differences emerged rom this study.

Liberia and the Universal Negro Improvement Association: The background to the abortion of Garvey's scheme for African colonization

In July 1924, the Liberian government suddenly banned the Universal Negro Improvement Association from Liberia, and this after over four years of apparent co-operation with the Association in its plans to settle New World Negroes in Liberia and generally to aid Liberia financially. Yet the ban could not have surprised anyone familiar with Liberian matters. The Liberian economy, which at the advent of the Association in 1920 was in a very bad state, was beginning to recover independently of the Association. Moreover, Britain and France, which had colonies nearby, abhorred the Association's anti-colonialism crusade, and Liberia feared to alienate these powers. But most importantly, the ruling Americo-Liberian class feared that the Association's immigrants might challenge its already entrenched, privileged position in Liberia, and probably end its exploitation and oppression of Liberia's indigenous African population, which provided labour and revenue for this class and for the Liberian government generally.

Causes of perinatal death in Uganda Africans, with special reference to congenital malformations

<h2>Summary</h2> The causes of perinatal deaths in Uganda Africans were studied in a series of 102 necropsies at Mulago Hospital, Kampala. Major congenital defects seem to be relatively uncommon as a cause of death compared with other populations. No congenital heart disease was seen, and only one case of anencephaly and one of spina bifida. Birth trauma is a common cause of perinatal death and is often associated with prolonged labor. Craniotomy was necessary in 6 cases, and death was associated with rupture of the uterus in 3. This is the first such study in an indigenous African population.