The HLA system in the Korean population

Doctors Discussing "the Root of Koreans": Medical Genetics and the Korean Origin, 1975-1987

Anthropological genetics emerged as a new discipline to investigate the origin of human species in the second half of the twentieth century. Using the genetic database of blood groups and other protein polymorphisms, anthropological geneticists started redrawing the ancient migratory history of human populations. A peculiarity of the Korean experience is that clinical physicians were the first experts using genetic data to theorize the historical origin of the respective population. This paper examines how South Korean physicians produced the genetic knowledge and discourse of the Korean origin in the 1970s and 1980s. It argues that transnational scientific exchange led clinical researchers to engage in global anthropological studies. The paper focuses on two scientific cooperative cases in medical genetics at the time: the West German-South Korean pharmacogenetic research on the Korean population and the Asia-Oceania Histocompatibility Workshop. At the outset, physicians introduced medical genetics into their laboratory for clinical applications. Involved in cooperative projects on investigating anthropological implications of their clinical work, medical researchers came to use their genetic data for studying the Korean origin. In the process, physicians simply followed a nationalist narrative of the Korean origin rather than criticizing it. This was partially due to their lack of serious interest in anthropological work. Their explanations about the Korean origin would be considered "scientific" while hiding their embracing of the nationalist narrative.

The expression of MAGE and GAGE genes in uterine cervical carcinoma of Korea by RT-PCR with common primers

BACKGROUND

Melanoma antigen genes (MAGE) and GAGE genes are encoded by genes that are silent in virtually all normal adult tissues but are expressed in tumors from various tissues. These gene products are targets for specific immunotherapy as they are presented by HLA I molecules and recognized by autologous cytotoxic T-lymphocytes. However, the characteristics of these genes, especially in uterine cervical cancer are relatively unknown.

PURPOSE

This study evaluated the prevalence of MAGE and GAGE by reverse transcription-polymerase chain reaction (RT-PCR) with common primers and discusses clinical implications in cervical carcinoma.

MATERIALS AND METHODS

Fresh tissue from 37 cases of primary squamous cell carcinoma and normal cervical mucosa were evaluated for clinicopathologic parameters including Human Papilloma Virus (HPV)-16,18 infection by PCR, tumor stage by FIGO classification and lymph node involvement. RT-nested PCR for the MAGE and GAGE genes was performed with common primers and DNA sequencing after subcloning was used for identification of PCR products of MAGE. Formalin-fixed paraffin embedded material from the same specimen was analyzed by in situ RT-PCR for MAGE.

RESULTS

Expression of MAGE and GAGE was not observed in normal tissues. Eleven out of 37 cases expressed MAGE mRNA (29.7%): analysis of subtypes identified one case of MAGE-1, two cases of MAGE-4b, six cases of MAGE-3, and two unknown subtypes. Thirteen out of 37 cases (35.1%) expressed GAGE mRNA. No significant relationships between expression of these genes and FIGO staging, lymph node metastasis or HPV infection were found.

CONCLUSION

Expression of MAGE and GAGE may be involved in the development of uterine cervical carcinoma from intraepithelial neoplasia, although without distinct prognostic significance. MAGE and GAGE genes have the potential to be used as targets for the treatment of uterine cervical carcinoma.

Decreased trabecular bone mineral density in newly diagnosed inflammatory bowel disease patients in Korea

BACKGROUND

Decreased bone mineral density (BMD) is common in Western patients with inflammatory bowel disease (IBD). However, BMD has never been studied in Asia where the demographic and socio-economic status are different from the West. The aim of this study was to investigate the prevalence and mechanisms of osteopenia in newly diagnosed Korean patients with IBD.

METHODS

We studied 14 patients with Crohn's disease (CD) and 25 patients with ulcerative colitis (UC), all of whom had never been treated with corticosteroids. Bone mineral density was measured in the lumbar spine and the femoral neck by dual energy X-ray absorptiometry. Biochemical parameters including serum osteocalcin, parathyroid hormone, plasma inactive and active vitamin D, and urinary deoxypyridinoline were measured.

RESULTS

The BMD Z score at the lumbar spine was lower both in CD and in UC patients, but there was no significant difference between the two groups. There was no significant difference in nutritional status or biochemical parameters of bone metabolism between patients with a normal BMD and those with a decreased BMD.

CONCLUSIONS

Low BMD at the lumbar spine is common in newly diagnosed Korean patients with IBD, a result which is similar to Western studies. The mechanism for low bone mass remains undetermined; however, nutritional status and hormonal parameters of bone metabolism, and ethnic differences are not likely to be an important factor in the pathogenesis of this bone loss.

HLA haplotypes in Koreans based on 107 families

There are marked differences in the distribution of HLA haplotypes among different populations, and multilocus HLA haplotypes can best be studied by family analysis. In the present study, 107 Korean families were analyzed for HLA-A, B, C, DR, and DQ antigens and haplotypes. Allele frequencies of more than 10% for class I antigens were A2, A24, A33, B44, B62, Cwl, Cw7, Cw9, Cw10, and C blank (CBL) and those for class II antigens were DR4, DR8, DR13, DR15, DQ1, DQ3, DQ4 and DQ7. In the analysis of HLA haplotypes, 18 kinds of A-B-DR and 11 kinds of A-C-B-DR-DQ haplotypes occurred at frequencies of more than 1%, comprising 34% and 24% of the total theoretical haplotypes, respectively. The five most common A-B-DR haplotypes were exclusively related with the five most common A-C-B-DR-DQ haplotypes (frequency>2%). These remarkably conserved five-locus haplotypes in Koreans were A33-CBL-B44-DR13-DQ1 (5.4%), A24-Cw7-B7-DR1-DQ1 (3.5%), A33-Cw7-B44-DR7-DQ2 (3.0%), A33-Cw10-B58-DR13-DQ1 (2.3%), and A30-Cw6-B13-DR7-DQ2 (2.3%). Comparison of the distribution of A-B-DR haplotypes among East Asian populations revealed that Koreans are closest to Japanese, but show a higher degree of polymorphism in the distribution of HLA haplotypes compared to Japanese. The results obtained in this study will be useful as basic data on Koreans for anthropology and organ transplantation.

DR6 in Koreans. DR11 frequently acts as a recipient gene to create DR13 alleles

DR6 is a complex allele family composed of at least 16 different alleles. Although 25% of Koreans express DR6 alleles, this allele family has not been well studied in the population. DNA samples obtained from 252 unrelated individuals were screened by PCR using Taq DNA polymerase and a DRB1 group-specific PCR primer set that amplifies the polymorphic second exon of DR3, DR11, and DR6 DRB1 alleles. To identify the DR6 allelic frequencies in this population, PCR-positive samples were further analyzed by dot-blot hybridization using digoxigenin-labeled SSOPs. In this process, a new DRB1 allele was identified by its unique hybridization pattern and was further characterized by direct sequencing after PCR. The new DRB1 sequence is similar to DRB1*1101, differing at codon 47 (TAC[Tyr]/TTC[Phe]) and at codon 58 (GCC[Ala]/GAG[Glu]). Based on sequence comparisons as well as its DRB3 and DQ associations, the new allele may have arisen by a gene conversion event from DRB1*1101. The resultant DR molecule bears DR6 serologic determinants as determined by serologic typing and, based on sequence, is probably a DR13 and not a DR14 allele. These data suggest that the DR11 allele has frequently acted as a recipient gene in the gene conversion events that created the subfamily of DR13 alleles, DRB1*1303, *1304, *1305, and the new allele described here.

Allotypes of the fourth component of complement in Koreans

The analysis of genetic polymorphism in C4 was performed on EDTA-plasma from 169 healthy unrelated Koreans. Plasma samples were subjected to high-voltage agarose gel electrophoresis followed by immunofixation. C4B allotypes were further detected by a hemolytic overlay method. The allele frequencies of C4A and C4B were as follows; for C4A, C4A*3 = 0.6099, C4A*4 = 0.1702, C4A*Q0 = 0.1525, C4A*2 = 0.0461, and C4A*R = 0.0213; for C4B, C4B*1 = 0.6406, C4B*2 = 0.2740, C4B*5 = 0.0569, C4B*Q0 = 0.0178, and C4B*R = 0.0107. C4A*3 and C4B*1 were among the most common alleles at each locus. C4A*6 was not detected in this study, but this allele is relatively common in both Caucasoid and Negroid populations. C4B*5 is a common allele in Asian, which is rare in Caucasoids and Negroids. C4B*5 appeared to be a characteristic allele of Oriental. In the C4A locus, five individuals with duplicated allotypes (three C4A 3,3 + 2, one C4A 4,3 + 2, and one C4A 3,3 + 3) were observed, and in the C4B locus, one individual with duplicated allotype (C4B 1,1 + 1) was detected.

HLA Typing of Takayasu arteritis in Korea

Takayasu arteritis occurs with a strong predilection for women and particular geographic areas, and as related to the etiology of the disease, association of HLA antigens has been suggested. In the present study, the authors investigated the association of Takayasu arteritis with class I and class II HLA antigens in 59 Korean patients with this disease. Increased frequencies of HLA-Bw52 (chi 2 6.213, P < 0.02), Cw6 (chi 2 4.132, P < 0.05), DR7 (chi 2 4.506, P < 0.04), and DQw2 (chi 2 7.327, P < 0.01) were observed in the patient group as compared to the control group of healthy Koreans. In the Korean population, 2 risk factors in the HLA system for developing this disease appear to be (1) Bw52 and (2) DR7 and a probable haplotype of Cw6, B13, DR7, DQw2. Previous studies of the Japanese population revealed association of Bw52 and class II HLA antigens (DR2, Dw12), which are in linkage disequilibrium with Bw52. It is of interest that in the Korean population, class II antigens (DR7, DQw2), which are not linked to BW52, are associated with the disease. This finding suggests that the disease susceptibility gene of Takayasu arteritis is located between the HLA-B locus and HLA-DR, DQ loci.

HLA-DR and -DQ DNA genotyping in seven populations of Asia-Oceania and Australia

Haplotype patterns of HLA-DR and -DQ restriction fragment length polymorphisms (RFLPs) were compared in seven populations in the region of Asia-Oceania: Australian Caucasoids, Melanesians, micronesians, Polynesians, Chinese, Koreans, and Japanese. Several DR beta RFLP patterns, including those correlating with DR2, 4,5, w6, 7 and w8 in Caucasoids, were associated with multiple DQ alpha/DQ beta RFLP haplotypes, of which only two occurred universally - one associated with DR4 and one with DR5. RFLPs revealed new population or group specific characteristics, which had not been previously discovered using serological or cellular HLA typing techniques. The populations of Asia-Oceania have some features of the class II RFLPs in common, which are distinctly different from Caucasoids. On the other hand, a number of characteristics distinguish between the various Asian and Pacific groups. This study demonstrates the power of RFLP analysis of closely linked genes in population genetics, and shows the value of ethnic comparisons in further characterizing the polymorphisms of the HLA class II genes.

HLA and leprosy in Koreans

HLA antigens in 157 unrelated Koreans with leprosy have been identified and compared with 162 healthy Korean controls. The patient group consisted of 124 with lepromatous leprosy and 33 with tuberculoid leprosy. Although no significant differences were detected between the two patient groups, several antigens were found to be increased in the combined patient group compared to healthy controls. Two Class I antigens were increased: HLA-A11 (22% vs 12%) and Aw33 (27% vs 14%). Four Class II antigens were increased: HLA-DR1 (16% vs 7%), DR2 (39% vs 21%), DRw9 (14% vs 6%) and DQw1 (74% vs 55%). HLA-DR4 (28% vs 48%), DRw53 (46% vs 69%) and DQw3 (50% vs 75%) in contrast were significantly decreased in patients. Interaction of DR1, DR2, DRw9 and DQw1 as risk factors was analyzed. HLA-DR2 appeared to be the strongest risk factor. No evidence for synergy between DR1, DR2 and DRw9 was detected. DQw1 was not significantly increased in patients in the absence of DR1 and DR2, and thus it was not apparent in this study that DQw1 was an independent risk factor.