HLA-linked genetic markers in Chinese and other Oriental populations

Allelic heterogeneity of HLA-B35 subtypes in different populations as assessed by DNA typing

HLA-B35, a class I antigen differentially associated to several diseases in different ethnic groups, comprises at least eight alleles which differ among them by one to six amino acids. In the present work a rapid DNA typing procedure was used to investigate the distribution of the various HLA-B35 alleles in different populations. The approach is based on a group-specific PCR amplification of a set of closely related HLA-B alleles sharing a Thr in position 45 of the alpha-1 domain. The amplified DNA was then hybridized to a panel of sequence-specific oligonucleotide (SSO) probes designed to recognize the polymorphic residues in previously reported HLA-B35 subtypes. This methodology was successfully tested in 100 individuals of four different populations, previously typed by serology as HLA-B35, and in six reference panel cells of the 10th International Histocompatibility Workshop. HLA-B*3501 was the predominant subtype in all populations. B*3502, B*3503 and, to a lesser extent B*3508, were also found. Among Mexican Mestizos, thirteen individuals had patterns of SSO hybridization suggestive of new B35 alleles. The evolutionary considerations on the different B35 alleles and their extended B35,Cw4 haplotypes are discussed.

Strong association of HLA-DR3 in Chinese patients with idiopathic membranous nephropathy

The frequency of HLA-DR3 was significantly increased in 22 adult Chinese patients with idiopathic membranous nephropathy. The frequency of HLA-Aw33 was also increased through close linkage disequilibrium with DR3.

The distribution of HLA-A,B, DR antigens in Chinese myasthenia gravis

The association of HLA antigens with Myasthenia Gravis (MG) in many different races is well known. In this study, HLA-A, B and DR antigens were typed on 65 Chinese MG and 232 controls for HLA-A, B and 61 for DR antigens. A2 and DRw9 increased significantly in patients with MG (p less than 0.025 and p less than 0.05 respectively). DR2 and DR4 had the opposite influence (both p less than 0.005). Several alleles were shown to have relatively high values of P D/A and relative risk but low P A/D and E.F, which suggests the marker heterogeneity of MG. Comparisons of clinically different types of MG, variations of the age of onset and thymic pathology did not show any statistically significant difference in HLA distributions. The clinical implications were discussed.

The HLA system in the Korean population

The frequencies of HLA-A, B, C, DR, and DQ antigens, HLA-D (HTC-defined) haplotypes, and the HLA-linked genetic markers glyoxalase I (GLO), factor B (Bf), C2 and C4 were studied in 162 healthy unrelated Koreans. Antigens A2, A24, A26, B44, B51, Bw62, B35, Cw1, Cw3, DR2, DR4, DRw6, DR7, and DRw8 were observed at frequencies of 15% or greater, and GLO-2, BfS, C4A*3, C2C, C4A*4, C4B*1, and C4B*2 were also frequently observed. The antigens A23, A25, B18, Bw42, Bw47, and B21 were not observed at all. HLA-DR4 was the most common class II antigen and was associated with a series of HLA-D-defined haplotypes including Dw4, Dw10, Dw13, and Dw15. The HLA-DRw6, DR2,Dw8, and DRw8 haplotypes were also found frequently. DR2 haplotypes were either Dw2 or Dw12, while all DRw8 haplotypes tested corresponded to the DB7 or Dw "8.3" specificity that has been described in other Oriental populations. Significant linkage disequilibrium was found between the alleles A2,Cw1; A30,B13; A30,Cw6; A30,DR7; Cw1,Bw22; Cw5,B12; Cw6,B13; Cw6,DR7; B7,DR1; B12,Dw6; B12,DR7; B12,Dw7; B13,DR7, B17,DR3; Bw22,C4B*6; DRw6,BfF; and C4A*4,C4B*2. A comparison of gene frequencies and commonly observed haplotypes between Koreans, Chinese, Japanese, and Caucasians showed that while Koreans share several characteristics in common with other Oriental populations, there are allelic frequencies and haplotypes in Koreans that are distinct.

HLA polymorphisms in a Han Chinese population of Sichuan

This study reports the phenotype frequencies (PF) and gene frequencies (GF) of a homogeneous Sichuan Han Chinese population by typing of unrelated 229 individuals and 16 families for HLA-A, B, C, DR and DQ antigens. The frequencies of Bw67, Bw71, DRw12, DRw13 and DRw14 are the first to be reported in Chinese. Two two-locus haplotypes with significant linkage disequilibrium among the Sichuan have also been listed.

Immunofixation for C2 typing: C2 allotypes in Spaniards in relation to HLA, Bf and C4

C2 typing is performed by immunofixation with anti-C2 antiserum instead of by a hemolytic overlay. This method gives sharp band definition, is less cumbersome than the hemolytic overlay, gel files are easily made, and it also enables one to describe putative new nonhemolytic variants. C2 allele frequencies were studied in a sample of the normal Spanish population and were found to be similar to other Caucasoids. HLA-Bw62,-Cw3, and -DR4 were significantly associated with C2 B. Concordantly, the only C2*B extended HLA haplotype found in family material was Bw62-Cw3-Bw6-(DR4)-Bf*S-C2*B-C4A*3 B*2-(GLO*1). C4A*4 B*2 and C4A*4 B*4 are not found within the same haplotype together with C2*B and Bw62 or Bw22 respectively, nor do other C2*B haplotypes occur with common HLA-B alleles. These results may favour the hypothesis that the Bw62-C2*B haplotype is produced by one mutation arising in the Bw62-C2*C haplotype and that subsequent crossovers can explain other C2*B haplotypes (including Bw22-C2*B).

The HLA system in the prevalent Mexican Indian group: the Nahuas

Results of HLA-A, B and C typing as well as haplotype frequencies in the Nahuas, who are the predominant Indian group in Mexico are presented. ABO and Rh blood groups show the genetic homogeneity of this population, since all of them were group O and Rh+. The most frequent antigens and haplotype are in general, the same as in some, but not all Amerindian tribes (Papago, Pimas, Zuñi from North America and Ixils from Guatemala). When compared to other Mongoloids, the HLA pattern is very close to the Japanese population. Antigens Bw39 and Cw4 look like markers of Nahuas and because Bw16 cells from four individuals could not be assigned either as Bw38 or Bw39, and 6 subjects did not type for any of the Bw22 splits, new subtypes of these antigens are probable.

HLA in two islands of French Polynesia

The HLA-A, B, and C antigens of 243 individuals from two Polynesian islands, Maiao and Hiva Oa, have been characterized. 328 haplotypes were defined by family analysis. Most frequent antigens were A2, A11, Aw24, A26 , Aw34 ; Bw38, Bw39 , Bw48 , Bw55 , Bw56 , Bw60 ; Cwl, Cw3, and Cw4. Several other antigens were present at low frequency or were present on only one island. New variants of Bw22 and B40 were found. Despite an overall similarity in antigens of the two islands, the combination of HLA-A, B and C antigens on the haplotype were distinctive. Of 328 total haplotypes identified, 65 were unique. Thirteen of these (20%) were present on both islands. Twenty-eight (43%) were unique to Hiva Oa and 24 (37%) were unique to Maiao . Significant, positive linkage disequilibrium values (delta) for HLA-A, B and HLA-B, C antigens were also different for the two populations.

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.