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Concept: Orang Asli

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BACKGROUND: In the first part of this study, we investigated the prevalence and associated key factors of soil-transmitted helminth (STH) infections among Orang Asli children in rural Malaysia; an alarming high prevalence and five key factors significantly associated with infections were reported. Part 2 of this study aims to evaluate the knowledge, attitude and practices (KAP) on STH infections among Orang Asli in Peninsular Malaysia. METHODS: A cross-sectional study was carried out among 215 households from 13 villages in Lipis district, Pahang, Malaysia. Demographic and socioeconomic information of the participants and their KAP on STH were collected by using a pre-tested questionnaire. RESULTS: Overall, 61.4% of the participants had prior knowledge about intestinal helminths with a lack of knowledge on the transmission (28.8%), signs and symptoms (29.3%) as well as the prevention (16.3%). Half of the respondents considered STH as harmful, while their practices to prevent infections were still inadequate. Significant associations between the KAP and age, gender, educational and employment status, family size, and household monthly income were reported. Moreover, significantly lower prevalence of STH infections was reported among children of respondents who wear shoes/slippers when outside the house (72.8%; 95% CI= 62.6, 80.5 vs 87.0%; 95% CI= 81.4, 91.1), wash their hands before eating (32.4%; 95% CI= 24.3, 42.2 vs 51.4%; 95% CI= 44.7, 60.1), and wash their hands after defecation (47.8%; 95% CI= 35.7, 57.1 vs 69.2%; 95% CI= 63.7, 78.7) as compared to their counterparts. Multiple logistic regression analysis indicated that the educational level of the respondents was the most important factor significantly associated with the KAP on STH among this population. CONCLUSION: This study reveals inadequate knowledge, attitude and practices on STH infections among Orang Asli in rural Malaysia. Hence, there is a great need for a proper health education programme and community mobilisation to enhance prevention and instil better knowledge on STH transmission and prevention. This is crucial for an effective and sustainable STH control programme to save the lives and future of the most vulnerable children in rural Malaysia.

Concepts: Regression analysis, Logistic regression, Intestinal parasite, Hookworm, Parasitic worm, Orang Asli, Pahang, Kelantan

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The flagellate protozoan parasite, Giardia intestinalis, is widely distributed throughout the world with a high prevalence in developing countries in the tropics and subtropics, including Malaysia. Approximately 200 million people are infected with the parasite globally, with 500,000 new cases reported annually. This cross-sectional study was conducted among three tribes of Orang Asli communities in Selangor, Perak and Pahang states of Malaysia. The main objective was to determine the prevalence of and risk factors for giardiasis. Stool samples were collected from 500 individuals aged between 2 and 74years (males=219, females=281). The samples were examined with formalin-ether sedimentation and trichrome staining techniques. Socioeconomic data were collected through a pre-tested questionnaire. The overall prevalence of giardiasis was 20.0% with the highest prevalence in the Proto-Malays (33.3%) followed by Negritos (20.1%) and Senois (10.4%). The positive cases showed a decrease with increasing age and most of the positive cases were observed in individuals less than 24years old. Males had significantly higher prevalence than females (χ(2)=5.283, P=0.022). Logistic regression analysis of the overall population studied and the Senoi tribe confirmed that being a child aged less than 15years, being male, the consumption of raw vegetables and the presence of other family members infected with G. intestinalis were the main risk factors for giardiasis. The presence of other family members infected with G. intestinalis was the only risk factor highlighted in the Proto-Malay and Negrito tribes. Diarrhoea was significantly associated with giardiasis. However, the cause and effect relationship has yet to be determined. Thus, screening family members and treating the infected individuals are the main strategies that should be adopted by the public health authority in combating this infection in Orang Asli communities as well as health education regarding good personal and food hygiene practises.

Concepts: Epidemiology, Giardia lamblia, Protozoa, Orang Asli, Pahang, Kelantan, Senoi, Negrito

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The Kelantanese Malays who resided in the remote northeastern regions of the Malay Peninsula in the Kelantan state are believed to have a unique genetic signature. The objective of this review is to analyze the populational sub-structure of the Kelantanese Malays from historical, genetic and linguistic perspectives. Historical data suggest that the Semang were composed of the Jahai, Bateq and Kensiu sub-tribes, whereas the Senoi were composed of only the Temiar sub-tribe. The Mendriq sub-tribe is believed to be the first group of aborigines to land in Kelantan. Subsequently, genetic analysis showed that the Kelantanese Malays are an independent clade at the base of the phylogenetic tree and contain genetic material similar to that of the Semang, specifically the Jahai and the Kensiu sub-tribes. The genetic data are supported by the fact that the Aslian language, a branch of the Austroasiatic languages that is widely spoken by the Semang, was potentially transmitted through agricultural activities. However, the potential limitation of this mini-review is the lack of primary reliable sources covering the historical, linguistic and genetic features of the Kelantanese Malays.

Concepts: Genetics, Southeast Asia, Thailand, Malaysia, Orang Asli, Malay Peninsula, Austro-Asiatic languages, Aslian languages

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Pigmentation is a readily scorable and quantitative human phenotype, making it an excellent model for studying multifactorial traits and diseases. Convergent human evolution from the ancestral state, darker skin, towards lighter skin colors involved divergent genetic mechanisms in people of European vs. East Asian ancestry. It is striking that the European mechanisms result in a 10-20-fold increase in skin cancer susceptibility while the East Asian mechanisms do not. Towards the mapping of genes that contribute to East Asian pigmentation there is need for one or more populations that are admixed for ancestral and East Asian ancestry, but with minimal European contribution. This requirement is fulfilled by the Senoi, one of three indigenous tribes of Peninsular Malaysia collectively known as the Orang Asli. The Senoi are thought to be an admixture of the Negrito, an ancestral dark-skinned population representing the second of three Orang Asli tribes, and regional Mongoloid populations of Indo-China such as the Proto-Malay, the third Orang Asli tribe. We have calculated skin reflectance-based melanin indices in 492 Orang Asli, which ranged from 28 (lightest) to 75 (darkest); both extremes were represented in the Senoi. Population averages were 56 for Negrito, 42 for Proto-Malay, and 46 for Senoi. The derived allele frequencies for SLC24A5 and SLC45A2 in the Senoi were 0.04 and 0.02, respectively, consistent with greater South Asian than European admixture. Females and individuals with the A111T mutation had significantly lighter skin (p = 0.001 and 0.0039, respectively). Individuals with these derived alleles were found across the spectrum of skin color, indicating an overriding effect of strong skin lightening alleles of East Asian origin. These results suggest that the Senoi are suitable for mapping East Asian skin color genes.

Concepts: Gene, Genetics, Evolution, Southeast Asia, Asia, Human skin color, Malaysia, Orang Asli

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Indigenous populations of Malaysia known as Orang Asli (OA) show huge morphological, anthropological and linguistic diversity. However, the genetic history of these populations remained obscure. We performed a high density array genotyping using over 2 million SNPs in 3 major groups of Negrito, Senoi and Proto-Malay. Structural analyses indicated that although all OA groups are genetically closest to East Asian (EA) populations, they are substantially distinct. We identified a genetic affinity between Andamanese and Malaysian Negritos which may suggest an ancient link between these two groups. We also showed that Senoi and Proto-Malay may be admixtures between Negrito and EA. Formal admixture tests provided evidence of gene flow between Austro-Asiatic speaking OAs and populations from Southeast Asia and South China which suggest a widespread presence of these people in SEA before Austronesian expansion. Elevated linkage disequilibrium (LD) and enriched homozygosity found in OAs reflect isolation and bottlenecks experienced. Estimates based on Ne and LD indicated that these populations diverged from East Asians during the late Pleistocene (14.5 to 8 YBP). The continuum in divergence time from Negritos to Senoi and Proto-Malay in combination with ancestral markers provides evidences of multiple waves of migration into SEA starting with the first Out-of-Africa dispersals followed by Early-train and subsequent Austronesian expansions.

Concepts: Southeast Asia, Population genetics, Asia, East Asia, Malaysia, Orang Asli, Negrito, Austronesian languages

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Copy number variations (CNVs) are genomic structural variations that result from the deletion or duplication of large genomic segments. The characterization of CNVs is largely underrepresented, particularly those of indigenous populations, such as the Orang Asli in Peninsular Malaysia. In the present study, we first characterized the genome-wide CNVs of four major native populations from Peninsular Malaysia, including the Malays and three Orang Asli populations; namely, Proto-Malay, Senoi, and Negrito (collectively called PM). We subsequently assessed the distribution of CNVs across the four populations. The resulting global CNV map revealed 3102 CNVs, with an average of more than 100 CNVs per individual. We identified genes harboring CNVs that are highly differentiated between PM and global populations, indicating that these genes are predominantly enriched in immune responses and defense functions, including APOBEC3A_B, beta-defensin genes, and CCL3L1, followed by other biological functions, such as drug and toxin metabolism and responses to radiation, suggesting some attributions between CNV variations and adaptations of the PM groups to the local environmental conditions of tropical rainforests.

Concepts: DNA, Gene, Genetics, Copy number variation, Malaysia, Orang Asli, Kelantan, Senoi

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The original version of this article contains an error. The Author Abd Rashid Nur Haslindawaty has been added as to the above author group as third author. The original article was corrected.

Concepts: Kuala Lumpur, Malaysia, Orang Asli, Pahang, Kelantan, Senoi, Constitution of Malaysia, Demographics of Malaysia

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Peninsular Malaysia is populated by the Malays, Chinese, Indians, and Orang Asli. We have analyzed 17 Y-STRs loci for 243 randomly unrelated individuals, which include 153 Malays (7 Acheh, 13 Champa, 11 Rawa, 9 Kedah, 23 Minang, 15 Bugis, 43 Kelantan, 14 Jawa, and 18 Bugis) and 90 Orang Asli [54 Semang (16 Kensiu, 13 Lanoh, 25 Bateq); 30 Senoi (21 Semai, 9 Che Wong); and 6 Proto-Malay (6 Orang Kanaq)] from selected settlements in Peninsular Malaysia using the AmpFlSTR Yfiler™ kit (Applied Biosystems™). The overall haplotype diversity is 0.9966, i.e., 0.9984 for the Malays and 0.9793 for the Orang Asli. A total of 158 haplotypes (65.02%) were individually unique. The p value and pairwise Rst analysis was calculated to show the genetic structure of the samples with other world populations (from YHRD website). Based on the Y-STR data, Champa, Acheh, Kedah, Minang, and Kelantan are clustered together. Lanoh and Kensiu (Semang) are very closely related, suggesting similar paternal ancestry. Jawa Malays and Indonesian Java, plus the Bugis Malays and Australian Aborigines shared high degree of paternal lineage affinity. This study presents data for very precious relict groups, who are the earliest inhabitants of Peninsular Malaysia.

Concepts: Indonesia, Malaysia, Orang Asli, Kelantan, Senoi, Peninsular Malaysia, Ethnic groups in Malaysia, Penang

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Thalassaemia is a public health problem in Malaysia, with each ethnic group having their own common mutations. However, there is a lack on data on the prevalence and common mutations among the indigenous people. This cross-sectional study was performed to determine the common mutations of α- and β-thalassaemia among the subethnic groups of Senoi, the largest Orang Asli group in Peninsular Malaysia. Blood samples collected from six Senoi subethnic groups were analysed for full blood count and haemoglobin analysis (HbAn). Samples with abnormal findings were then screened for α- and β-globin gene mutations. Out of the 752 samples collected, 255 showed abnormal HbAn results, and 122 cases showing abnormal red cell indices with normal HbAn findings were subjected to molecular screening. DNA analysis revealed a mixture of α- and β-globin gene mutations with 25 concomitant cases. The types of gene abnormalities detected for α-thalassaemia were termination codon (T>C) Hb CS (α(CS) α), Cd59 (G>A) haemoglobin Adana (Hb Adana) (α(Cd59) α), initiation codon (ATG>A-G) (α(IniCd) α), two-gene deletion (-(SEA) ), and single-gene 3.7-kb deletion (-α(3.7) ). For β-thalassaemia, there were Cd26 (G>A) Hb E (β(E) ), Cd19 (A>G) Haemoglobin Malay (Hb Malay) (β(Cd19) ), and IVS 1-5 (G>C) (β(IVS 1-5) ).

Concepts: DNA, Hemoglobin, Genetic code, Malaysia, Indigenous peoples, Orang Asli, Kelantan, Senoi

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CYP2D6 is one of the major enzymes in the cytochrome P450 monooxygenase system. It metabolizes ∼25% of prescribed drugs and hence, the genetic diversity of CYP2D6 gene has continued to be of great interest to the medical and pharmaceutical industries. This study aims to perform a systematic analysis of the CYP2D6 gene in six subtribes of the Malaysian Orang Asli.

Concepts: Pharmacology, Evolution, Metabolism, Cytochrome P450, Steroid, Enzymes, CYP2D6, Orang Asli