Yong-Hak Sohn

Human leukocyte antigen alleles and haplotypes associated with chronicity of hepatitis B virus infection in Koreans.

CONTEXT Chronic hepatitis B infection is the leading cause of cirrhosis and hepatocellular carcinoma. Human leukocyte antigen may be involved in the chronicity of hepatitis B virus (HBV) infection. OBJECTIVE To analyze the association between HBV chronicity and human leukocyte antigen alleles and haplotypes of 636 organ donors and recipients. DESIGN Subjects were categorized into 2 groups according to their clinical and serologic profiles, specifically, an HBV natural convalescent group and an HBV chronic carrier (CC) group. RESULTS Hepatitis B chronicity was positively associated with A33 (P = .004, odds ratio [OR] = 1.59) and DR7 (P < .001, OR = 2.58), and negatively associated with HLA-DR13 (P < .001, OR = 0.40). Coexpression of A33 and DR7 was significantly higher in the CC group (OR = 3.63), compared with that of either allele alone (OR = 1.76 in A33; OR = 2.53 in DR7). The statistically significant haplotypes were B44-DR7 (P < .001, OR = 5.44), A33-DR7 (P < .001, OR = 4.47), and A33-B44-DR7 (P < .001, OR = 7.31) in the CC group. CONCLUSIONS Our results indicate that alleles of A33, DR7, and haplotypes containing DR7 are associated with HBV chronicity among Koreans. Moreover, the 2 antigens had an additive effect on chronicity. These findings support the theory that human leukocyte antigen class I-restricted cytotoxic T cells and human leukocyte antigen class II-restricted helper T cells play an important role in HBV chronicity.

MICB polymorphisms and haplotypes with MICA and HLA alleles in Koreans

Major histocompatibility complex (MHC) class I chain-related gene B (MICB) is located within the human MHC class I region. The location of MICB in the MHC region may imply the presence of linkage disequilibrium with polymorphic MICA and human leukocyte antigen (HLA) loci. MICB is also polymorphic; however, MICB polymorphisms have not been investigated in Koreans. Using sequence-based typing (SBT), we estimated the allelic frequencies of MICB and haplotypes with MICA, HLA-B, and HLA-DRB1 at high resolution in a population of 139 unrelated Korean individuals. Eight MICB alleles were identified. The most frequent allele was MICB*005:02/*010 (57.2%), followed by *002 (11.5%), *004 (8.3%), *005:03 (8.3%), and *008 (6.8%). The most common two-locus haplotypes were MICB*005:02/*010-MICA*010 (19.4%), MICB*005:02/*010-DRB1*15:01 (6.5%), and MICB*005:02/*010-B*15:01 (10.4%); the most common three-locus haplotypes were B*15:01-MICA*010-MICB*005:02/*010 (5.8%) and MICA*010-MICB*005:02/*010-DRB1*04:06 (10.4%); and the most common four-locus haplotype was B*15:01-MICA*010-MICB*005:02/*010-DRB1*04:06 (5.8%). This is the first study to provide information about MICB allele frequencies and haplotypes with HLA in Koreans. These study results should help understand mechanisms of disease association between the MICB locus and neighboring loci in Koreans.

Anthropological analysis of Koreans using HLA class II diversity among East Asians.

Human leukocyte antigens (HLAs) are useful markers for anthropological investigations because the allele and haplotype distributions at these loci vary widely among ethnic groups. HLA frequencies in Koreans, however, have not previously been analyzed on a phylogenetic basis. We determined the allele frequencies of four HLA class II (HLA-DRB1, -DQA1, -DQB1, and -DPB1) loci in 149 unrelated Korean individuals using a sequence-based typing method. A total of 29 HLA-DRB1, 17 HLA-DQA1, 16 HLA-DQB1, and 15 HLA-DPB1 alleles were identified. The most common allele at each locus was DRB1*0901, DQA1*0102, DQB1*0301, and DPB1*0501, respectively. Four-locus allelic association analysis showed the existence of 25 DRB1-DQA1-DQB1-DPB1 haplotypes with a frequency greater than 0.010. A dataset comprising ethnicity-specific information from published literature and the dbMHC database, as well as the allele frequencies determined in this study, was subjected to phylogenetic analysis. The analysis showed that Koreans are most closely related to Japanese and Han Chinese from Shandong province. Correspondence analyses showed that the current Korean population is located in a position intermediate between the northern and southern East Asian groups, supporting the theory of a bi- and/or multidirectional route of migration of early Korean settlers. This report can be used for anthropological studies, and may also be of use in the International Hematopoietic Stem Cell Sharing program.

Identification of a novel HLA-DRB1 allele, DRB1*11:95

The DRB1*11:95 showed a single nucleotide difference with the DRB1*11:01:01 allele at codon 10 (TAC/TGC).

Performance evaluation of ExiStation HBV diagnostic system for hepatitis B virus DNA quantitation

Abstract The performance of a recently developed real-time PCR system, the ExiStation HBV diagnostic system, for quantitation of hepatitis B virus (HBV) in human blood was evaluated. The detection limit, reproducibility, cross-reactivity, and interference were evaluated as measures of analytical performance. For the comparison study, 100 HBV-positive blood samples and 100 HBV-negative samples from Korean Blood Bank Serum were used, and the results of the ExiStation HBV system showed good correlation with those obtained using the Cobas TaqMan (r 2 =0.9931) and Abbott real-time PCR systems (r 2 =0.9894). The lower limit of detection was measured as 9.55IU/mL using WHO standards and the dynamic range was linear from 6.68 to 6.68×109 IU/mL using cloned plasmids. The within-run coefficient of variation (CV) was 9.4%, 2.1%, and 1.1%, and the total CV was 11.8%, 3.6%, and 1.7% at a concentration of 1.92log10 IU/mL, 3.88log10 IU/mL, and 6.84log10 IU/mL, respectively. No cross-reactivity or interference was detected. The ExiStation HBV diagnostic system showed satisfactory analytical sensitivity, excellent reproducibility, no cross-reactivity, no interference, and high agreement with the Cobas TaqMan and Abbott real-time PCR systems, and is therefore a useful tool for the detection and monitoring of HBV infection.

Evaluation of three glucometers for whole blood glucose measurements at the point of care in preterm or low-birth-weight infants

Purpose We evaluated three blood glucose self-monitoring for measuring whole blood glucose levels in preterm and low-birth-weight infants. Methods Between December 1, 2012 and March 31, 2013, 230 blood samples were collected from 50 newborns, who weighed, ≤2,300 g or were ≤36 weeks old, in the the neonatal intensive care unit of Eulji University Hospital. Three blood glucose self-monitoring (A: Precision Pcx, Abbott; B: One-Touch Verio, Johnson & Johnson; C: LifeScan SureStep Flexx, Johnson & Johnson) were used for the blood glucose measurements. The results were compared to those obtained using laboratory equipment (D: Advia chemical analyzer, Siemens Healthcare Diagnostics Inc.). Results The correlation coefficients between laboratory equipment and the three blood glucose self-monitoring (A, B, and C) were found to be 0.888, 0.884, and 0.900, respectively. For glucose levels≤60 mg/dL, the correlation coefficients were 0.674, 0.687, and 0.679, respectively. For glucose levels>60 mg/dL, the correlation coefficients were 0.822, 0.819, and 0.839, respectively. All correlation coefficients were statistically significant. And the values from the blood glucose self-monitoring were not significantly different from the value of the laboratory equipment , after correcting for each devices average value (P>0.05). When using laboratory equipment (blood glucose ≤60 mg/dL), each device had a sensitivity of 0.458, 0.604, and 0.688 and a specificity of 0.995, 0.989, and 0.989, respectively. Conclusion Significant difference is not found between three blood glucose self-monitoring and laboratory equipment. But correlation between the measured values from blood glucose self-monitoring and laboratory equipment is lower in preterm or low-birth-weight infants than adults.

A processed HLA-A*24:02 pseudogene found in the peripheral blood of a father and his son.

We encountered a case that exhibited a discrepancy in human leukocyte antigen-A (HLA-A) type determined by sequence-based typing (SBT) and sequence-specific primer (SSP) molecular typing. The child of this case was identified as A* 02:01 homozygote and A* 02, A* 24, respectively. The HLA-A type of his father was A* 02:01, 26:01, but low-resolution SSP also showed unexpected amplification with A* 24 primers as with the child. Serologic typing of the child and the father was A2/blank and A2/A26, respectively. Sequencing analysis of the A* 24 variant in the child and the father showed a complete deletion of all introns of the A* 24:02 allele. Though rare, this type of processed pseudogene variant can be one of the causes of discrepancies between high- and low-resolution HLA typing.