FcγRIIB, the only inhibitory IgG Fc receptor, functions to suppress the hyper-activation of immune cells. Numerous studies have illustrated its inhibitory function through the ITIM motif in the cytoplasmic tail of FcγRIIB. However, later studies revealed that in addition to the ITIM, the transmembrane (TM) domain of FcγRIIB is also indispensable for its inhibitory function. Indeed, recent epidemiological studies revealed that a non-synonymous single nucleotide polymorphism (rs1050501) within the TM domain of FcγRIIB, responsible for the I232T substitution, is associated with the susceptibility to systemic lupus erythematosus (SLE). In this review, we will summarize these epidemiological and functional studies of FcγRIIB-I232T in the past few years, and will further discuss the mechanisms accounting for the functional loss of FcγRIIB-I232T. Our review will help the reader gain a deeper understanding of the importance of the TM domain in mediating the inhibitory function of FcγRIIB and may provide insights to a new therapeutic target for the associated diseases.
Autoimmune Diseases ; drug therapy ; genetics ; immunology ; Humans ; Protein Domains ; Receptors, IgG ; chemistry ; immunology

ATP-Binding Cassette Transporters ; genetics ; DNA Copy Number Variations ; genetics ; Genetic Predisposition to Disease ; Gout ; genetics ; Humans ; Receptors, IgG ; genetics ; Receptors, Interleukin-17 ; genetics

OBJECTIVETo assess the association of several single nucleotide polymorphisms and haplotypes of the FCGR2A gene with ulcerative colitis (UC) among Chinese patients.

METHODSFor 198 UC patients and 356 healthy controls, the alleles and genotypes of the FCGR2A gene (rs1801274, rs10800309 and rs6696854) were detected with a multiplex SNaPshot technique. All subjects were also subjected to linkage disequilibrium and haplotype analyses.

RESULTSThe mutant homozygote (CC) of the FCGR2A gene rs1801274 polymorphism was less frequent among UC patients compared with the controls (5.56% vs. 11.80%, P=0.017, OR=0.440, 95%CI: 0.221-0.875). However, the allelic and genotypic distributions of other two SNPs did not differ significantly between the two groups (all P>0.05). Furthermore, no association of the three SNPs (rs1801274, rs10800309 and rs6696854) of the FCGR2A gene with the severity and location of the UC was found (all P>0.05). The three SNPs were shown to be in a strong linkage [rs1801274-rs10800309 (D'=0.863, r=0.634); rs1801274-rs6696854 (D'=0.753, r=0.546); rs10800309-rs6696854(D'=0.990, r=0.802)]. Moreover, the frequency of T-A-T haplotype was higher among the UC patients compared with the controls (67.40% vs. 60.93%, P=0.032, OR=1.326, 95%CI: 1.024-1.717).

CONCLUSIONOur findings suggested that the mutant homozygote (CC) of the FCGR2A gene (rs1801274) may have a protective role among Chinese patients with UC. Moreover, the T-A-T haplotype formed by rs1801274, rs10800309 and rs6696854 may confer a higher risk for UC.

Adult ; Asian Continental Ancestry Group ; genetics ; Colitis, Ulcerative ; genetics ; Female ; Genetic Predisposition to Disease ; genetics ; Haplotypes ; genetics ; Humans ; Polymorphism, Single Nucleotide ; genetics ; Receptors, IgG ; genetics

BACKGROUNDTakayasu arteritis (TA) is a rare inflammatory arteriopathy of unknown etiology. The aim of this study was to investigate the genetic susceptibility to TA in a Chinese population.

METHODSFour single nucleotide polymorphisms (SNPs) those locate in the IL12B region (rs56167332), the MLX region (rs665268), the FCGR2A/FCGR3A locus (rs10919543), and the HLA-B/MICA locus (rs12524487), associated with TA in different population, were genotyped in 123 Chinese TA patients and 147 healthy controls from January 2013 to August 2014. A Chi-square test was used to test for genotype/allele frequencies variants.

RESULTSAmong the four SNPs, rs10919543 was found to be significantly associated with TA in the studied population. The GG genotype of rs10919543 at the FCGR2A/FCGR3A locus is a high risk factor (odds ratio [OR] = 6.532, 95% confidence interval [CI] = 2.402 - 17.763, P < 0.001) for TA. Among TA patients, the level of eosinophil granulocytes (Eos) in the peripheral blood was observed to be higher in the GG group of rs10919543 (n = 23, Eos = 0.11 [0.08, 0.17] ×109/L) than the GA + AA group (n = 100, Eos = 0.08 [0.05, 0.13] ×109/L, P = 0.028). No correlation between the genotypes of the other three SNPs and TA patients was observed.

CONCLUSIONSOur findings revealed unique genetic pattern in Chinese TA patients that may be partly responsible for the higher risk of TA in this population. FCGR2A/FCGR3A-related immune disorder might contribute to the etiology of TA.

Adolescent ; Adult ; Child ; Female ; Genetic Predisposition to Disease ; Humans ; Male ; Middle Aged ; Polymorphism, Single Nucleotide ; Receptors, IgG ; genetics ; Takayasu Arteritis ; etiology ; genetics

Rheumatoid arthritis (RA) is a chronic, inflammatory, autoimmune disorder that principally attacks flexible joints and synovia. The precise pathogenesis of RA remains unclear, and genetic factors probably play an important role in its etiology. In addition to genes from human leukocyte antigen (HLA) region, such as HLA-DRB, genes from non-HLA region, such as TIM-3, PTPN22, TRAF1/C5, STAT4, CCR5, PADI4 and FCGR2A may also contribute to its susceptibility. The advance in molecular genetics research on RA is reviewed here.
Arthritis, Rheumatoid ; genetics ; Exome ; Genetic Predisposition to Disease ; HLA-DRB1 Chains ; genetics ; Hepatitis A Virus Cellular Receptor 2 ; Humans ; Membrane Proteins ; genetics ; Protein Tyrosine Phosphatase, Non-Receptor Type 22 ; genetics ; Receptors, IgG ; genetics

Adult ; Aged ; Autoimmune Diseases ; genetics ; Case-Control Studies ; Female ; Genetic Predisposition to Disease ; Genotype ; Humans ; Male ; Middle Aged ; Polymorphism, Single Nucleotide ; Receptors, IgG ; genetics ; Thrombocytopenia ; genetics ; Young Adult

OBJECTIVETo evaluate the impact of Fc gamma receptor IIIa (FcγR IIIa) polymorphisms on the efficacy of rituximab (RTX) combined chemotherapy for patients with diffuse large B-cell lymphoma (DLBCL).

METHODSFcγRIIIa polymorphisms were analyzed by PCR in 122 patients and 100 healthy controls. All patients received 8(4-12) cycles of RTX combined chemotherapy.

RESULTS78(63.93%) patients with F/F, 5(4.10%) with V/V, and 39(31.97%) with V/F were identified, which were not different compared to controls. Patients with different FcγRIIIa genotypes did not have any difference in terms of gender, age, molecular subtypes, lactate dehydrogenase (LDH) or international prognostic index (IPI). The overall response rate (ORR) was 89.35% with a complete response (CR) of 80.33% and a partial response (PR) of 9.02%. The ORR was 83.33%, 100.00% and 100.00% in F/F, V/V and V/F, respectively. A higher response rate was observed in V/V and V/F as compared with F/F (P<0.05). With a median follow-up of 35 months (range: 12-62 months), 46(37.71%) patients had relapsed and 40 (32.79%) cases progressed and ended in death. The 3-year progress-free survival (PFS) rate was 41.03%, 100.00%, 100.00% in F/F, V/V and V/F, respectively. The 3-year overall survival (OS) rate was 48.72%, 100.00% and 100.00% in patients with three genotypes. The PFS and OS rate were significantly higher in V/V and V/F as compared with F/F (P<0.05).

CONCLUSIONFcγR III a polymorphisms could predict response and prognosis of RTX combined chemotherapy for patients with DLBCL.

Antibodies, Monoclonal, Murine-Derived ; administration & dosage ; Antineoplastic Combined Chemotherapy Protocols ; therapeutic use ; Asian Continental Ancestry Group ; genetics ; Disease-Free Survival ; GPI-Linked Proteins ; Humans ; Lymphoma, Large B-Cell, Diffuse ; drug therapy ; genetics ; Polymorphism, Genetic ; Prognosis ; Receptors, IgG ; genetics ; Remission Induction ; Rituximab

BACKGROUND: Human neutrophil antigens (HNAs) are involved in autoimmune and alloimmune neutropenia and transfusion-related acute lung injury. The HNA-1 system is important in immunogenetics, and allele frequencies have been described in different populations. This study investigated the frequency of FCGR3B alleles encoding HNA-1a, HNA-1b, and HNA-1c among Thai blood donors and compared these frequencies with those previously reported for other populations. METHODS: Eight hundred DNA samples obtained from unrelated healthy blood donors at the National Blood Centre, Thai Red Cross Society, Bangkok, and the Blood Bank, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand, were included. Samples were simultaneously typed for each FCGR3B allele using an in-house polymerase chain reaction with sequence-specific primer (PCR-SSP) technique. RESULTS: The frequencies of FCGR3B*1, FCGR3B*2, and FCGR3B*3 alleles in central Thai blood donors were 0.548, 0.452, and 0.004, respectively; only FCGR3B*1 and FCGR3B*2 alleles were found in northern Thai blood donors (0.68 and 0.32, respectively). Compared with other Asian populations, central Thais had higher frequencies of the FCGR3B*2 allele (P<0.001), while the frequencies of the FCGR3B*1 and FCGR3B*2 alleles in northern Thais were similar to those previously reported in Taiwanese and Japanese populations. In contrast, the frequencies of the FCGR3B*1 and FCGR3B*2 alleles in the northern Thai population were statistically different from those observed in central Thai, Korean, German, and Turkish populations. CONCLUSIONS: FCGR3B allele frequencies were significantly different between central and northern Thai blood donors. Our in-house PCR-SSP method is a simple, cost-effective, and convenient method for FCGR3B allele detection.
Asian Continental Ancestry Group/*genetics ; *Blood Donors ; DNA/analysis ; DNA Primers/chemistry/metabolism ; GPI-Linked Proteins/genetics ; Gene Frequency ; Genotype ; Humans ; Polymerase Chain Reaction ; Receptors, IgG/*genetics ; Thailand

Behcet's disease (BD) is a chronic systemic inflammatory disorder characterized by four major manifestations: recurrent uveitis, oral and genital ulcers and skin lesions. To identify some pathogenic variants associated with severe Behcet's uveitis, we used targeted and massively parallel sequencing methods to explore the genetic diversity of target regions. A solution-based target enrichment kit was designed to capture whole-exonic regions of 132 candidate genes. Using a multiplexing strategy, 32 samples from patients with a severe type of Behcet's uveitis were sequenced with a Genome Analyzer IIx. We compared the frequency of each variant with that of 59 normal Korean controls, and selected five rare and eight common single-nucleotide variants as the candidates for a replication study. The selected variants were genotyped in 61 cases and 320 controls and, as a result, two rare and seven common variants showed significant associations with severe Behcet's uveitis (P<0.05). Some of these, including rs199955684 in KIR3DL3, rs1801133 in MTHFR, rs1051790 in MICA and rs1051456 in KIR2DL4, were predicted to be damaging by either the PolyPhen-2 or SIFT prediction program. Variants on FCGR3A (rs396991) and ICAM1 (rs5498) have been previously reported as susceptibility loci of this disease, and those on IFNAR1, MTFHR and MICA also replicated the previous reports at the gene level. The KIR3DL3 and KIR2DL4 genes are novel susceptibility genes that have not been reported in association with BD. In conclusion, this study showed that target enrichment and next-generation sequencing technologies can provide valuable information on the genetic predisposition for Behcet's uveitis.
Adult ; Aged ; Behcet Syndrome/*genetics ; Case-Control Studies ; Female ; Histocompatibility Antigens Class I/genetics ; Humans ; Intercellular Adhesion Molecule-1/genetics ; Interferon-alpha/genetics ; Male ; Middle Aged ; *Polymorphism, Single Nucleotide ; Receptors, IgG/genetics ; Receptors, KIR/genetics ; Receptors, KIR2DL4/genetics

OBJECTIVETo study the association of FCGR2A gene single nucleotide polymorphism (SNP) rs1801274 with Kawasaki disease (KD) susceptibility and the efficacy of intravenous immunoglobulin (IVIG) therapy in Han Chinese children.

METHODSThirty-five KD children and 25 age-and gender-matched healthy children (control group) were enrolled in the study. Polymerase chain reaction (PCR) and gene sequence analysis were applied to detect SNP of FCGR2A gene rs1801274. These KD patients were classified into two subgroups based on the presence of coronary artery lesion (CAL) following IVIG therapy: CAL (n=13) and non-CAL (n=22).

RESULTSFCGR2A gene SNP rs1801274 was detected in all subjects, including three genotypes (AA, AG and GG). For FCGR2A gene SNP rs1801274, there were significant differences in the genotype and allele frequencies between the KD and control groups (P<0.05), and significant differences in the genotype and allele frequencies were also found between the CAL and non-CAL subgroups (P<0.05). A allele and AA genotype were linked to an increased risk of KD susceptibility (A allele: OR=3.39, 95%CI:1.53-7.50; AA genotype: (OR=4.93, 95%CI:1.61-15.1). Both AG (OR=5.43, 95%CI:1.06-27.8) and G allele (OR=4.88, 95%CI:1.44-16.5) were linked to an increased risk of CAL in KD children.

CONCLUSIONSPolymorphism of the FCGR2A gene SNP rs1801274 is one of the important factors probably influencing susceptibility to KD and efficacy of IVIG therapy on KD in Han Chinese children.

Asian Continental Ancestry Group ; genetics ; Child ; Child, Preschool ; Female ; Gene Frequency ; Genetic Predisposition to Disease ; Genotype ; Humans ; Infant ; Male ; Mucocutaneous Lymph Node Syndrome ; genetics ; Polymorphism, Single Nucleotide ; Receptors, IgG ; genetics