High-Resolution Analyses of Human Leukocyte Antigens Allele and Haplotype Frequencies Based on 169,995 Volunteers from the China Bone Marrow Donor Registry Program.

Allogeneic hematopoietic stem cell transplantation is a widely used and effective therapy for hematopoietic malignant diseases and numerous other disorders. High-resolution human leukocyte antigen (HLA) haplotype frequency distributions not only facilitate individual donor searches but also determine the probability with which a particular patient can find HLA-matched donors in a registry. The frequencies of the HLA-A, -B, -C, -DRB1, and -DQB1 alleles and haplotypes were estimated among 169,995 Chinese volunteers using the sequencing-based typing (SBT) method. Totals of 191 HLA-A, 244 HLA-B, 146 HLA-C, 143 HLA-DRB1 and 47 HLA-DQB1 alleles were observed, which accounted for 6.98%, 7.06%, 6.46%, 9.11% and 7.91%, respectively, of the alleles in each locus in the world (IMGT 3.16 Release, Apr. 2014). Among the 100 most common haplotypes from the 169,995 individuals, nine distinct haplotypes displayed significant regionally specific distributions. Among these, three were predominant in the South China region (i.e., the 20th, 31st, and 81sthaplotypes), another three were predominant in the Southwest China region (i.e., the 68th, 79th, and 95th haplotypes), one was predominant in the South and Southwest China regions (the 18th haplotype), one was relatively common in the Northeast and North China regions (the 94th haplotype), and one was common in the Northeast, North and Northwest China (the 40th haplotype). In conclusion, this is the first to analyze high-resolution HLA diversities across the entire country of China, based on a detailed and complete data set that covered 31 provinces, autonomous regions, and municipalities. Specifically, we also evaluated the HLA matching probabilities within and between geographic regions and analyzed the regional differences in the HLA diversities in China. We believe that the data presented in this study might be useful for unrelated HLA-matched donor searches, donor registry planning, population genetic studies, and anthropogenesis studies.

[To identify a novel HLA-DRB1 allele in Chinese by sequencing].

OBJECTIVE: To identify a novel HLA-DRB1 allele in Chinese. METHODS: A novel HLA-DR allele was detected by PCR-SSP and SBT in a patient with leukemia. RESULTS: The sequence of the novel allele was different from all other known alleles. The novel allele differed from the closet matching allele HLA-DRB1*1404 by one nucleotide substitution in exon 2, at position 33 T>C, this resulted in an amino acid change from Tyr to His at codon 17. CONCLUSION: The novel allele is confirmed as a new HLA allele and it was officially named HLA-DRB1*1461 by WHO Nomenclature Committee in May, 2006.

[Investigation on induced expansion of erythroid cells from cord blood CD34(+) cells in vitro].

This study was aimed to investigate a beneficial approach for resolving the deficiency of blood source, preventing the infection resulting from blood transfusion and overcoming the knotty match of patients with rare blood group by using massive expansion of erythroid cells from cord blood CD34(+) cells in vitro. The CD34(+) cells from human cord blood were cultured in serum-free medium supplemented with stem cell factor (SCF), interleukin-3 (IL-3) and erythropoietin (EPO) for 1 week, then expansion and differentiation of CD34(+) cells into erythroid cells were supported by co-culture with human mesenchymal stem cells (MSCs) derived from bone marrow for 2 weeks. The results indicated that after culture for 23 days, the expansion multiple of total cell number reached 2.52 x 10(5), and over 95% of these cells were erythroid cells as compared with less than 1% of myelomonocytic (CD14(+) or CD15(+)) cells and megakaryocytic (CD41(+)) cells. However, the culture system without MSC support was significantly disadvantaged both in expansion ability and ratio of erythroid cells when compared with MSC supporting system. It is concluded that the erythroid cells can be produced from CD34(+) cells in large scale by culturing in the system comprised of cytokine sets and MSC feeders, in which MSCs can support the proliferation and differentiation of erythroid cells.

[A recombination event occurring between HLA-B and DRB1 loci within a Chinese Han family].

OBJECTIVE: To investigate a recombination event occurring between the HLA-B and DRB1 loci in a Chinese family with a leukemia patient. METHODS: HLA class I (-A and -B) low resolution typing was carried out by polymerase chain reaction-sequence specific oligonucleotide, PCR-SSO). HLA class II low resolution typing was performed by PCR-sequence specific primer (PCR-SSP). And HLA class I and II high resolution typing was done by sequencing-based typing (SBT). Then the recombination event was analyzed by family study. RESULTS: The 2 haplotypes of the patient were A*3101-B*1301-DRB1*0701 and A*3303-B*4403-DRB1*1302. His father's 2 haplotypes were A*3001-B*1302-DRB1*0701 and A*3101-B*1301-DRB1*1501. Family study demonstrated that the HLA-A*3101-B*1301 was from one of his father's chromosome and the DRB1*0701 was from the other chromosome of his father. So the result indicated that the recombination event occurred between the HLA-B and -DRB1 loci during meiosis of his father and resulted in a new HLA haplotype that was transferred to the son. CONCLUSION: A HLA-B/DR recombination event occurring between the HLA-B and -DRB1 loci has been found in a Chinese family, which may help further study of the mechanism of HLA recombination.

[A novel mutation in the myocilin gene identified in a Chinese primary open angle glaucoma family].

OBJECTIVE: To determine the possible myocilin molecular genetic defect underlying POAG in China and to identify the pathogenic mutation causing the disease. METHODS: The majority of 1 branch of a large Chinese POAG family were personally examined by two senior ophthalmologists. The diagnoses were made by both doctors according to the signs of elevated intraocular pressure, glaucomatous optic neuropathy and glaucomatous visual field defect. All coding sequences of the myocilin gene plus the flanking sites were amplified by polymerase chain reaction (PCR) using genomic DNA from all examined family members followed by sequencing of the PCR products. One hundred normal control subjects were screened by single strand confirmational polymorphism analysis for the mutation. RESULTS: This Chinese pedigree exhibited autosomal dominant mode of inheritance. The onset age ranged from 26 to 59 years. A novel disease-causing missense mutation T455K in the third exon of the myocilin gene was identified in all affected family members, all glaucoma suspects and 4 individuals who have not shown apparently signs of glaucoma. None of the subjects without the mutation had glaucoma. Affected individuals with the T455K mutation showed variable onset between 26 and 59 years of age. Filtering surgery was performed on all of 7 affected family members. The T455K mutation in myocilin gene was not found in the normal controls. A previously reported polymorphism IVS2+35(A to G)was detected in 4 individuals. CONCLUSION: The novel myocilin sequence alteration T455K that is highly associated with the development of glaucoma and locates in a very conserved residue is proven to be a disease-causing missence mutation. All affected individuals and all POAG suspects in this family are identified to have this mutation. The mutation in this family is associated with a phenotype characterized by mix-onset open angle glaucoma and associated with a high penetrance. It is important for the mutation screening and periodical checkups of presymptomatic individuals belonging to the family of a POAG patient with T455K mutation.