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Human natural killer (NK) cells are essential for controlling infection, cancer, and fetal development. NK cell functions are modulated by interactions between polymorphic inhibitory killer cell immunoglobulin-like receptors (KIR) and polymorphic HLA-A, -B, and -C ligands expressed on tissue cells. All HLA-C alleles encode a KIR ligand and contribute to reproduction and immunity. In contrast, only some HLA-A and -B alleles encode KIR ligands and they focus on immunity. By high-resolution analysis of KIR and HLA-A, -B, and -C genes, we show that the Chinese Southern Han (CHS) are significantly enriched for interactions between inhibitory KIR and HLA-A and -B. This enrichment has had substantial input through population admixture with neighboring populations, who contributed HLA class I haplotypes expressing the KIR ligands B*46:01 and B*58:01, which subsequently rose to high frequency by natural selection. Consequently, over 80% of Southern Han HLA haplotypes encode more than one KIR ligand. Complementing the high number of KIR ligands, the CHS KIR locus combines a high frequency of genes expressing potent inhibitory KIR, with a low frequency of those expressing activating KIR. The Southern Han centromeric KIR region encodes strong, conserved, inhibitory HLA-C-specific receptors, and the telomeric region provides a high number and diversity of inhibitory HLA-A and -B-specific receptors. In all these characteristics, the CHS represent other East Asians, whose NK cell repertoires are thus enhanced in quantity, diversity, and effector strength, likely augmenting resistance to endemic viral infections.

The molecular basis of MNS blood group variants is not fully clear yet. In this study, we have characterized mRNA variants of GYPA and GYPB genes to reveal whether alternative RNA splicing may cause antigenic diversity of the MNS system.Total RNA was extracted from peripheral blood of Chinese blood donors and full-length cDNA products were generated. A nested polymerase chain reaction (PCR)-based method was established for fragment amplification and Sanger sequencing. Resulted full-length mRNA sequences were aligned with GYPA or GYPB genomic sequences respectively for exon identification. Amino acid (AA) sequences of GPA and GPB proteins were extrapolated and GYPA-EGFP, GYPB-EGFP fusion genes were generated to monitor subcellular distribution of the encoded glycophorin (GP) proteins.Totally 10 blood samples were analysed. GYPB mRNAs of all the subjects demonstrated frequent exon insertion or deletion whereas this kind of variation was only observed in 3 of 10 GYPA mRNA samples. None of the reported Miltenberger hybrids was detected in any of the mRNA samples. The alternative splicing resulted in changes of AA sequences in N-terminal domains where the MNS antigenic motifs resided; however, subcellular localizations of GP-EGFP fusion proteins showed that the above-mentioned AA changes did not affect cell surface distribution of the encoded GP proteins.Alternative RNA splicing may influence the antigenic features of GP proteins but not their cell surface distribution. Therefore, GYPA and GYPB mRNA characterization might be an invaluable supplement to serological phenotyping and DNA-based genotyping in MNS blood grouping.

Background Appropriate iodine intake for adults is essential to reduce the prevalence of thyroid diseases, but there is little research data on iodine requirement of Chinese population. This study aimed to explore the iodine requirement of young adults to maintain a healthy status based on ‘overflow theory’. Methods Iodine-balance experiment has been performed in this project. We conducted an 18-day study consisted of a 6-day acclimation period and 3 consecutive experimental stages in 37 Chinese healthy young adults (23 female and 14 male). Each stage was consumed for 4 days. Strictly-controlled low-iodine intake diets were provided for adults in the first period, an egg or 125mL milk was added in the second and third period, respectively. The dietary samples, 24-h urine specimens and faeces of volunteers were collected daily for assessment of iodine intake and excretion in volunteers. Results Mean values of iodine intake (22.7±3.6, 35.1±3.7, and 52.2±3.8μg/d), excretion (64.7±13.9, 62.3±12.6, and 94.3±14.5μg/d) and iodine balance (-35.2±19.5, -21.0±19.8, and -33.5±26.9μg/d) were significantly different among three periods for male (PP < 0.001 for all). No significant difference was observed among the 3 periods for female in the iodine balance (-30.5±9.3, -25.9±7.3, and -27.6±12.1μg/d). The linear regression equation of iodine excretion on iodine intake was Y=0.979X+37.04 (male) and Y=0.895X+31.48 (female). Compared with stage 2, iodine excretion increments in stage 3 had exceeded the iodine intake increment for men. The ratio of increment was 1.675 for male when the average iodine intake was 52.2μg/d in stage 3. When the iodine excretion increment equaled to the iodine intake increment, the daily iodine intake of men was 47.0μg. Conclusion We have evaluated the iodine requirement of young adults in southern China based on overflow theory. Our results indicate the lower limit of iodine requirement for Chinese young men is 47.0μg/d. The trial was registered at www.chictr.org.cn as ChiCTR1800014877.

To verify a HLA-DQB1*03:90N allele and method to improve the accuracy of HLA typing.A total of 2265 hematopoietic stem cell donors from Shenzhen Branch of China Marrow Donor Program in 2018 were initially detected by a PCR sequence-specific oligonucleotide probe (SSOP) method. Among these, a rare HLA-DQB1 allele was identified by sequence-based tying (SBT) and Ion Torrent S5 next generation sequencing (NGS).The SSOP typing result suggested the HLA-DQB1 to be a rare allele, while an insertion and a deletion was suspected in its exon 2 by SBT, which were confirmed by NGS as DQB1*03:90N and DQB1*06:01, respectively.Rare alleles suspected by the SSOP method should be verified by other methods to ensure the accuracy of HLA genotyping. Rare alleles formed by deletions can be detected by NGS with accuracy.

HLA-DQB1*06:01:22 differs from HLA-DQB1*06:01:01:01 by one nucleotide substitution in codon 189 in exon 4.

HLA-A*24:02:78 differs from HLA-A*24:02:01:01 in exon 3 by a single nucleotide.

Background Hepatitis B virus (HBV) infection is one of the major concerns for the safety of blood transfusion in high-prevalent countries such as in China. Prior studies outside of China have shown hepatitis B surface antigen (HBsAg) false-reactive rate of 0.02% to 0.04%. Similarly, false-negative HBsAg and HBV DNA results may occur in infected donors. Our study analyzed HBsAg enzyme-linked immunosorbent assay (ELISA)-reactive but NAT-negative donations in Shenzhen Blood Center, China. Study design and methods HBsAg ELISA-positive/NAT-negative plasma samples identified from screening 101,025 donations during 2017-2018 were analyzed by molecular and serologic tests including neutralization, chemiluminescence immunoassays, and various HBV DNA amplification assays. Molecular characterizations of HBsAg-positive/NAT-negative samples were determined by quantitative polymerase chain reaction (qPCR) and nested PCR amplification of the basic core and precore promotor regions (295 base pairs) and HBsAg (S) region (496 base pairs). Results Screening of 101,025 eligible blood donations identified 157 (0.16%, 95% confidence interval, 0.13%-0.18%) HBsAg ELISA-positive/NAT-negative plasma samples; of those, 71 (45.2%) were HBsAg confirmed positive by further HBsAg testing and DNA positive by molecular tests with increased sensitivity. Of the 71, all but one was antibody to hepatitis B core antigen reactive without antibody to hepatitis B surface antigen, yielding one recent (window-period) HBV infection. Of the remaining donations, 80 (51%) were not considered as HBV-infected donors, and 6 (3.8%) were interpreted as indeterminate since HBsAg results were discordant with unconfirmed HBV DNA results. In the 71 confirmed positives, HBsAg levels ranged from 0.05 to 400 IU/mL and HBV DNA from 6 to 2654 IU/mL; however, the correlation between the two was weak (R2 = 0.24). Conclusion Fewer than half of HBsAg ELISA-positive/NAT-negative samples were confirmed as HBsAg positive. Our study demonstrates that in highly HBV-endemic countries, assays with high sensitivity and specificity may be required.

Background Blood donor plasma samples were detected by the Ultrio Plus NAT system for HBV, HCV and HIV-1 in Shenzhen blood center, China. Reactive samples underwent further discriminatory testing of a single virus by the same methodology. A large number of cases of non-discriminated reactive (NDR) donors were found, leaving potential risk of transmitting HBV if not deferrals. This study identified those non-discriminated samples. Methods The NDR plasma samples from blood donation screening were detected and classified by additional molecular and serological tests. Molecular characterizations of DNA+ NDR were determined by sequencing analysis. Results A number of 259 (0.21%) NDR plasma samples from screening of 123,280 eligible blood donors were detected, which presented a higher rate (91.1%) of anti-HBc reactivity and nearly half (46.7%) of HBV DNA+ that classified as occult HBV infection (OBI). Most OBI strains were wild-type HBV, but some substitutions V168A, S174 N, V177A, Q129R/L/H, G145A/R in S region of genotype B (OBIB) and T47K/V/A, P49H/L, Q101R/H/K, S174 N, L175S, V177A, T118 M/R/K, G145R/A/K/E, R160K/N in S region of genotype C (OBIC) strains were identified in high frequency. Conclusion Nearly half of NDR blood samples were identified as OBI, in which a number of important mutations were detected. NDR donation might have potential risk for HBV transmission, but need to be further investigated.

To assess the association of KIR/HLA alleles with hepatocellular carcinoma (HCC) and hepatitis B virus (HBV) infection among ethnic Han Chinese patients from southern China.For 95 patients with HCC and 171 healthy controls, the genotype of HLA-C alleles was determined with a PCR sequence-specific oligonucleotides typing method on an Illumina GenDx NGSgo platform. Genotypes comprised of HLA-C and KIR gene alleles were also subjected to statistical analysis.In total 16 KIR genes (2DL2, 2DS2, 2DS3, 2DS5, 3DS1, 2DS1, 2DL5, 2DS4, 3DL1, 3DP1, 2DL3, 2DP1, 3DL3, 2DL1, 3DL2 and 2DL4) were discovered in the two groups. The frequencies of KIR2DL3 alleles and combinational genotypes of KIR2DL3/HLA-C1C2 were significantly lower in the patient group compared with the controls (0.9368 vs. 0.9883, χ²3.84; P0.05, OR = 0.1; 0.0112 vs. 0.2663, χ²3.84; P0.05, RR = 0.03). The frequency of HLA-C2C2 genotype of the patient group was significantly lower than that of the controls (0.0316 vs. 0.2690, P0.05, RR = 0.09), while the frequency of HLA-C1C2 genotype was significantly higher than that of the controls (0.2316 vs. 0.0058, P0.05, RR = 51.23).Above results suggested that the KIR2DL3 allele is associated with lower risk for HCC. There may be individual difference in patients with HCC and HBV infection but various combinations of KIR/HLA alleles.

To study the distribution of MICA alleles among ethnic Han Chinese blood donors from Shenzhen and their linkage disequilibrium with HLA-B gene.For 143 randomly selected blood donors, the MICA and HLA-B alleles were determined with a PCR-sequence based typing (SBT) method. Allelic frequency, haplotypic diversity and linkage disequilibrium were analyzed with a Pypop software.Thirteen MICA and 35 HLA-B alleles were identified among the 143 blood donors, among which MICA*008:01 had the highest frequency (76/286), whilst MICA*008:01-HLA-B*40:01 and MICA*010-HLA-B*46:01 were the most common haplotypes. No novel allele was identified.The allele frequencies, haplotype diversities and linkage disequilibrium parameters under a high resolution can facilitate further studies and applications of the MICA and HLA-B genes.

Purpose Pathologic myopia described as myopia accompanied by severe deformation of the eye besides excessive elongation of eye, is usually a genetic heterogeneous disorder characterized by extreme, familial, early-onset vision loss. However, the exact pathogenesis of pathologic myopia remains unclear. In this study, we screened a Han Chinese family with pathologic myopia to identify the causative mutation and explore the possible pathogenic mechanism based on evaluation of the biological functions of the mutation. Methods We identified the mutations in a family with pathologic myopia by single nucleotide polymorphism array combined with short tandem repeat microsatellite marker analysis and exome sequencing. Mutations were validated among family members by direct Sanger sequencing. The subcellular localization of the protein variant was investigated by immunofluorescence, and the stability of the mutant protein was determined by immunoblotting. Intracellular levels of adenosine triphosphate and reactive oxygen species and complex I activity were measured by traditional biochemical methods to determine the functional role of the disease-associated mutation. Results The novel missense mutation: c.798C>G (p.Asp266Glu) in NDUFAF7, cosegregated with the disease and the resulting amino acid substitution affected a highly conserved residue in its protein. The mutation D266E in NDUFAF7 impaired complex I activity, which resulted in decreased ATP levels in cultured cells. Conclusions We propose that the heterozygous mutation (c.798C>G) in NDUFAF7 may contribute to the pathogenesis of pathologic myopia, possibly by interfering with the phototransduction cascade. Mitochondrial dysfunction during eye development may lead to pathologic myopia.