COVID-19 is a respiratory disease caused by a novel coronavirus and is currently a global pandemic. HLA variation is associated with COVID-19 because HLA plays a pivotal role in the immune response to pathogens. Here, 82 individuals with COVID-19 were genotyped for HLA-A, -B, -C, -DRB1, -DRB3/4/5, -DQA1, -DQB1, -DPA1, and -DPB1 loci using next-generation sequencing (NGS). Frequencies of the HLA-C*07:29, C*08:01G, B*15:27, B*40:06, DRB1*04:06, and DPB1*36:01 alleles were higher, while the frequencies of the DRB1*12:02 and DPB1*04:01 alleles were lower in COVID-19 patients than in the control population, with uncorrected statistical significance. Only HLA-C*07:29 and B*15:27were significant when the corrected P-value was considered. These data suggested that some HLA alleles may be associated with the occurrence of COVID-19.

The distributions of HLA allele and haplotype are variable in different ethnic populations and the data for some populations have been published. However, the data on HLA-C and HLA-DQB1 loci and the haplotype of HLA-A, HLA-B, HLA-C, HLA-DRB1 and HLA-DQB1 loci at a high-resolution level are limited in Zhejiang Han population, China. In this study, the frequencies of the HLA-A, HLA-B, HLA-C, HLA-DRB1 and HLA-DQB1 loci and haplotypes were analysed among 3,548 volunteers from the Zhejiang Han population using polymerase chain reaction sequencing-based typing method. Totals of 51 HLA-A, 97 HLA-B, 45 HLA-C, 53 HLA-DRB1 and 27 HLA-DQB1 alleles were observed.The top three frequent alleles of HLA-A, HLA-B, HLA-C, HLA-DRB1 and HLA-DQB1 loci were Ahaplotypes with a frequency of ≥0.1% were found and the haplotypes with frequency greater than 3% were Ahood ratios test for the linkage disequilibrium of two loci haplotypes was revealed that the majority of the pairwise associations were statistically significant. The data presented in this study will be useful for searching unrelated HLA-matched donor, planning donor registry and for anthropology studies in China. K E Y W O R D Sallele frequency, human leucocyte antigen, polymerase chain reaction sequencing-based typing

The distributions of HLA allele and haplotype are various in the populations. Currently, the data for HLA alleles and haplotypes at three fields resolution level in Chinese Han population is rare. Here, the HLA alleles and haplotypes of the 1734 cord blood samples from Zhejiang Han population, China were reported at three fields resolution. All samples were randomly collected from the Zhejiang Cord Blood Bank, China. HLA-A, -B, -C, -DRB1, -DQB1, -DRB3/4/5 loci was genotyped using next generation sequencing method. The genotypes of the samples were assigned using the HLA TypeStream Visual Software version 1.2.0. The frequency of alleles, haplotype estimation and linkage disequilibrium analysis were performed with the Arlequin software 3.5.2.2. It was found that the top three frequent alleles of HLA-

Immune rejection hinders the application of human embryonic stem cells (hESCs) in transplantation therapy. Human leukocyte antigens (HLAs) on the cell surface are the major cause of graft rejection. In this study, we generated HLA class I-deficient hESCs via disruption of beta 2-microglobulin (β2m), the light chain of HLA Class I. We found that HLA class I proteins were not present on the cell surface of β2m-null hESCs. These cells showed the same pluripotency as wildtype hESCs and demonstrated hypoimmunogenicity. Thus, HLA class I-deficient hESCs might serve as an unlimited cell source for the generation of universally compatible "off-the-shelf" cell grafts, tissues or organs in the future.

<b><i>Introduction:</i></b> The characteristic of ABO blood subgroup is crucial for elucidating the mechanisms of such variant phenotypes and offering useful information in blood transfusion. <b><i>Methods:</i></b> In total, 211 ABO variants including part of available family members were investigated in this study. The phenotypes of these individuals were typed with serologic methods. The full coding regions of <i>ABO</i> gene and the erythroid cell-specific regulatory elements in intron 1 of them were amplified with polymerase chain reaction and then directly sequenced. The novel alleles were confirmed by cloning and sequencing. Phylogenetic tree was made using CLUSTAL W software. 3D structural analyses of the glycosyltransferases (GTs) with some typical mutations were performed by PyMOL software. <b><i>Results:</i></b> Forty-eight distinctly rare <i>ABO</i> alleles were identified in 211 Chinese variant individuals, including 16 novel <i>ABO</i> alleles. All of the alleles were categorized as 5 groups: 16 <i>ABO</i>*<i>A</i> alleles, 23<i> ABO</i>*<i>B</i> alleles, 4 <i>ABO</i>*<i>BA</i> alleles, 4 <i>ABO</i>*<i>cisAB</i> alleles, and 1 <i>ABO</i>*<i>O</i> alleles. <i>ABO</i>*<i>A2.08</i> and <i>ABO</i>*<i>BA.02</i> were the relatively predominant <i>A</i> and <i>B</i> subgroup alleles, respectively. According to the phylogenetic tree, 28 alleles (5 common alleles and 23 alleles identified in our laboratory) were classified into 3 major allelic lineages. The structural analysis of 3D homology modeling predicted reduced protein stability of the mutant GTs and may explain the reduced ABO antigen expression. <b><i>Conclusions:</i></b> The molecular basis of ABO variants was analyzed, and 16 novel <i>ABO</i> alleles were identified. The results extended the information of ABO variants and provided a basis for better transfusion strategies and helped to improve blood transfusion safety.