The KIR system shows variation at both gene content and allelic level across individual genome and populations. This variation reflects its role in immunity and has become a significant tool for population comparisons. In this study, we investigate KIR gene content in 120 unrelated individuals from the four Malay subethnic groups (Kelantan, Jawa, Banjar and Pattani Malays). Genotyping using commercial polymerase chain reaction-sequence-specific primer (PCR-SSP) kits revealed a total of 34 different KIR genotypes; 17 for Kelantan, 15 for Banjar, 14 for Jawa and 13 for Pattani Malays. Two new variants observed in Banjar Malays have not previously been reported. Genotype AA and haplotype A were the most common in Jawa (0.47 and 0.65, respectively), Banjar (0.37 and 0.52, respectively) and Pattani (0.40 and 0.60, respectively) Malays. In contrast, Kelantan Malays were observed to have slightly higher frequency (0.43) of genotype BB as compared with the others. Based on the KIR genes distribution, Jawa, Pattani and Banjar subethnic groups showed greater similarity and are discrete from Kelantan Malays. A principal component plot carried out using KIR gene carrier frequency shows that the four Malay subethnic groups are clustered together with other South-East Asian populations. Overall, our observation on prevalence of KIR gene content demonstrates genetic affinities between the four Malay subethnic groups and supports the common origins of the Austronesian-speaking people.
The aboriginal populations of Peninsular Malaysia, also known as Orang Asli (OA), comprise three major groups; Semang, Senoi and Proto-Malays. Here, we analyzed for the first time KIR gene polymorphisms for 167 OA individuals, including those from four smallest OA subgroups (Che Wong, Orang Kanaq, Lanoh and Kensiu) using polymerase chain reaction-sequence specific primer (PCR-SSP) analyses. The observed distribution of KIR profiles of OA is heterogenous; Haplotype B is the most frequent in the Semang subgroups (especially Batek) while Haplotype A is the most common type in the Senoi. The Semang subgroups were clustered together with the Africans, Indians, Papuans and Australian Aborigines in a principal component analysis (PCA) plot and shared many common genotypes (AB6, BB71, BB73 and BB159) observed in these other populations. Given that these populations also display high frequencies of Haplotype B, it is interesting to speculate that Haplotype B may be generally more frequent in ancient populations. In contrast, the two Senoi subgroups, Che Wong and Semai are displaced toward Southeast Asian and African populations in the PCA scatter plot, respectively. Orang Kanaq, the smallest and the most endangered of all OA subgroups, has lost some degree of genetic variation, as shown by their relatively high frequency of the AB2 genotype (0.73) and a total absence of KIR2DL2 and KIR2DS2 genes. Orang Kanaq tradition that strictly prohibits intermarriage with outsiders seems to have posed a serious threat to their survival. This present survey is a demonstration of the value of KIR polymorphisms in elucidating genetic relationships among human populations.
Killer cell immunoglobulin-like receptors (KIR) gene frequencies have been shown to be distinctly different between populations and contribute to functional variation in the immune response. We have investigated KIR gene frequencies in 370 individuals representing three Asian populations in Singapore and report here the distribution of 14 KIR genes (2DL1, 2DL2, 2DL3, 2DL4, 2DL5, 2DS1, 2DS2, 2DS3, 2DS4, 2DS5, 3DL1, 3DL2, 3DL3, 3DS1) with two pseudogenes (2DP1, 3DP1) among Singapore Chinese (n = 210); Singapore Malay (n = 80), and Singapore Indian (n = 80). Four framework genes (KIR3DL3, 3DP1, 2DL4, 3DL2) and a nonframework pseudogene 2DP1 were detected in all samples while KIR2DS2, 2DL2, 2DL5, and 2DS5 had the greatest significant variation across the three populations. Fifteen significant linkage patterns, consistent with associations between genes of A and B haplotypes, were observed. Eighty-four distinct KIR profiles were determined in our populations, 38 of which had not been described in other populations. KIR haplotype studies were performed using nine Singapore Chinese families comprising 34 individuals. All genotypes could be resolved into corresponding pairs of existing haplotypes with eight distinct KIR genotypes and eight different haplotypes. The haplotype A2 with frequency of 63.9% was dominant in Singapore Chinese, comparable to that reported in Korean and Chinese Han. The A haplotypes predominate in Singapore Chinese, with ratio of A to B haplotypes of approximately 3:1. Comparison with KIR frequencies in other populations showed that Singapore Chinese shared similar distributions with Chinese Han, Japanese, and Korean; Singapore Indian was found to be comparable with North Indian Hindus while Singapore Malay resembled the Thai.
Transplantation and transfusion are related and clinically important areas of multidisciplinary expertise, including pre-operative treatment, donor recruitment, tissue matching, and post-operative care. We have seen significant developments in these areas, especially in the late 20th and early 21st century. This paper reviews the latest advances in modern transplantation and transfusion medicine, including several new genetic markers (e.g., major histocompatibility complex class I chain-related gene A, killer cell immunoglobulin-like receptor, and human platelet antigens) for donor and recipient matching, genotyping platforms (e.g., next-generation sequencer and Luminex technology), donor recruitment strategies, and several clinical applications in which genotyping has advantages over agglutination tests (e.g., genotyping of weakly expressed antigens and determination of blood groups and human leukocyte antigen types in multi-transfused patients). We also highlight the roles of population studies and international collaborations in moving towards more efficient donor recruitment strategies.
This article explores the genetic history of the various sub-populations currently living in Peninsular Malaysia. This region has received multiple waves of migrants like the Orang Asli in prehistoric times and the Chinese, Indians, Europeans and Arabs during historic times. There are three highly distinct lineages that make up the Orang Asli; Semang, Senoi and Proto-Malays. The Semang, who have 'Negrito' characteristics, represent the first human settlers in Peninsular Malaysia arriving from about 50,000ya. The Senoi later migrated from Indochina and are a mix between an Asian Neolithic population and the Semang. These Asian genomes probably came in before Austroasiatic languages arrived between 5000 and 4000years ago. Semang and Senoi both now speak Austro-Asiatic languages indicative of cultural diffusion from Senoi to Semang. In contrast, the Proto-Malays who came last to the southern part of this region speak Austronesian language and are Austronesians with some Negrito admixture. It is from this group that the contemporary Malays emerged. Here we provide an overview of the best available genetic evidences (single nucleotide polymorphisms, mitochondrial DNA, Y-chromosome, blood groups, human platelet antigen, human leukocyte antigen, human neutrophil antigen and killer-cell immunoglobulin-like receptor) supporting the complex genetic history of Peninsular Malaysia. Large scale sampling and high throughput genetic screening programmes such as those using genome-wide single nucleotide polymorphism analyses have provided insights into various ancestral and admixture genetic fractions in this region. Given the now extensive admixture present in the contemporary descendants of ancient sub-populations in Peninsular Malaysia, improved reconstruction of human migration history in this region will require new evidence from ancient DNA in well-preserved skeletons. All other aspects of the highly diverse and complex genetic makeup in Peninsular Malaysia should be considered carefully for genetic mapping of disease loci and policy formation by health authorities.
A vast proportion of coronavirus disease 2019 (COVID-19) individuals remain asymptomatic and can shed severe acute respiratory syndrome (SARS-CoV) type 2 virus to transmit the infection, which also explains the exponential increase in the number of COVID-19 cases globally. Furthermore, the rate of recovery from clinical COVID-19 in certain pockets of the globe is surprisingly high. Based on published reports and available literature, here, we speculated a few immunovirological mechanisms as to why a vast majority of individuals remain asymptomatic similar to exotic animal (bats and pangolins) reservoirs that remain refractile to disease development despite carrying a huge load of diverse insidious viral species, and whether such evolutionary advantage would unveil therapeutic strategies against COVID-19 infection in humans. Understanding the unique mechanisms that exotic animal species employ to achieve viral control, as well as inflammatory regulation, appears to hold key clues to the development of therapeutic versatility against COVID-19.