The distribution of HL-A leukocyte antigens in Singapore Chinese, Malays, and Indians

The polymorphism of HLA antigens in the Chinese

Remarkable differences were observed in antigen frequencies (AF), gene frequencies (GF) and haplotype frequencies (HF) when 2441 healthy Chinese individuals representing nine different ethnic groups and living in 14 different geographic locations were examined for the genetic distribution of the various HLA Class I and II markers. A sizable number of individuals of each ethnic group within each of the three major categories of the Chinese population, namely, Hans, Mongols, and Southern minorities, have been studied here, providing useful population statistics for applications such as determination of probabilities of paternity, comparisons for HLA and disease associations, and anthropologic studies.

Distribution of HLA antigens in a sample of the North Indian Hindu population

The Indian population can be divided broadly into Dravidians and the Aryans. In this report, we have attempted to analyze the HLA genetic profile of 400 native North Indian Hindus of Aryan descent. The gene frequencies of a majority of class I and II antigens show similarity to the Caucasoid population. An interesting finding was a complete lack of antigen B14 while B16 and B41 occurred with the least frequency. Haplotype A10, B8 with significant positive linkage disequilibrium as well as showing the highest incidence is characteristic of North Indians.

HLA antigens in South India: I. Major groups of Tamil Nadu

HLA-A, B profile of 385 normal healthy individuals living in Tamil Nadu, India was studied by microlymphocytotoxicity testing. Antigen, gene and haplotype frequencies of this population were calculated and compared to those already available in the literature. The sample was further divided into four major groups and the frequencies calculated. Genetic distances between the various major groups were also calculated: the analyses suggest that these different groups may differ by origin. The study further reveals that in any HLA genetic and disease association studies in India, one should give due consideration to the caste system of the sample studied.

HLA polymorphisms in a Shanghai Chinese population

The frequencies of the HLA-A, B, C, D, DR and MB antigens have been determined in a homogeneous Shanghai Chinese population. Comparisons with the HLA-A and -B frequencies in other subsets of the Chinese population revealed some marked differences. No comparisons were possible for the D, DR and MB antigens since there were no previous studies of the antigens in those loci. We suggest that studies of the Chinese population should be confined to clearly defined homogeneous subsets. In this manner, the confounding effect of population heterogeneity may be avoided, and it is this heterogeneity which calls for extensive surveys of the huge Chinese population.

HLA antigen frequency in the Koya tribe of Andhra Pradesh, India

The frequencies of HLA-A, -B, and -C antigens were studied in a tribal population of Koya from Andhra Pradesh in southern India. No other well-defined tribal population has been studied with which the present results may be compared. However, the HLA profile of Koya showed distinct differences from the general HLA distribution in India in the frequency of a large number of antigens both at the A and B loci. This study indicates the distinctiveness of this tribal population and suggests the potential importance of the study of HLA frequencies in tribal groups of India.

HLA-linked genetic markers in Chinese and other Oriental populations

The polymorphic variants of the HLA-linked genetic markers Bf, C2, C4 and GLO-I were studied in three mongoloid populations. Analysis of linkage dis-equilibrium between these markers and HLA-A, B, C and DR antigens was carried out on test results from 140 unrelated Chinese individuals. The phenotypes BfS and GLO-2 were found at significantly higher frequencies than in Caucasians. BfS was associated with B12 in Japanese but not in Chinese. A single individual with the rare Bf variant S1 was found. No C2 deficient individuals were observed. The C2C (common) allele occurred at a gene frequency of 0.949 and the more basic allele C2B at 0.039. The acidic variant, C2A, was observed at a frequency of 0.011 and appeared to be associated with BfF. Eighty-nine per cent of the Chinese were phenotypically C4FS. In contrast to Bf and C2, each of which is coded for by codominant alleles at a single genetic locus, C4 is coded for by two genes, C4F (Rodgers) and C4S (Chido). The C4F locus allele, C4F1 (extra fast), was strongly associated with HLA-B17, as has been found in other populations, but a new association of the C4S locus deficiency allele, C4so (Ch-), with B17 was also observed. All HLA-B17;C4so haplotypes were BfS position. As has been previously found in Caucasian populations, individuals of the C4F phenotype (i.e. genotypically FsoFso) were all found to be Chido negative. The frequencies of the various HLA-linked genetic markers, however, as much as the frequencies and associations of the HLA antigens themselves, distinguish these populations from other ethnic groups.

HLA-A, B and C antigens in South Indian families with leprosy

Seventy-two families, selected for having at least two children affected with leprosy, were HLA typed for 57 A, B and C locus antigens recognized by the WHO Nomenclature Committee. In addition, 20 possible new "splits" were investigated. The distribution of A, B and C locus antigens in affected and unaffected family members was similar, irrespective of the type of leprosy in the family. Gene frequencies (derived by direct gene counting from 253 haplotypes), haplotype frequencies and delta values were calculated. There is evidence for heterogeneity of B5, B15, B17, Bw16 and Bw35 and for the existence of at least one A locus and one B locus antigen not previously detected. The value of the HLA system for detecting expaternal children in a highly inbred population and the effect of inbreeding on the HLA system is discussed.

HL-A antigens in a Chinese population

The HL-A antigens of a Chinese population now living on the island of Taiwan have been investigated with reagents obtained from and characterized in Caucasian populations and with antisera obtained from Chinese multiparous women. Both HL-A2, the most frequent specificity found, and HL-A9 appear highly heterogeneous in this Chinese population since groups of antisera used to define HL-A2 or 9 in Caucasians gave discordant reactions. Moreover, new associations were found using chi-square and cluster analyses, further demonstrating the complexity of HL-A in this Taiwanese population. Fourteen % of 1183 Chinese multipara sera and 237 sera from multiple tranfused individuals were lymphocytotoxic and could be placed by cluster analysis into three major groups.

HL-A antigens in congenital rubella and the role of antigens 1 and 8 in the epidemiology of natural rubella

Study of 87 patients (53 adults, 23 males; 34 children, 18 males) with congenital rubella revealed an increased incidence of several HL-A antigens, including HL-A5, HL-A1, HL-A3 and HL-A8, the frequency of HL-A1 being raised because of the statistically significant increase of this antigen in the adult female subjects compared with normal controls. Correlation of the level of seropositivity to rubella virus in 29 normal adult populations, according to racial origin and geographic location, with the frequency of various HL-A antigens revealed the most significant association with HL-A1 (r equals 0.71). It is suggested that the presence on the cell surface of HL-A1 or the combination of HL-A1 and 8 may fovour rubella virus infection.