Genetic variants in five novel loci including CFB and CD40 predispose to chronic hepatitis B.

UNLABELLED: Hepatitis B virus affects more than 2 billion people worldwide, 350 million of which have developed chronic hepatitis B (CHB). The genetic factors that confer CHB risk are still largely unknown. We sought to identify genetic variants for CHB susceptibility in the Chinese population. We undertook a genome-wide association study (GWAS) in 2,514 CHB cases and 1,130 normal controls from eastern China. We replicated 33 of the most promising signals and eight previously reported CHB risk loci through a two-stage validation totaling 6,600 CHB cases and 8,127 controls in four independent populations, of which two populations were recruited from eastern China, one from northern China and one from southern China. The joint analyses of 9,114 CHB cases and 9,257 controls revealed significant association of CHB risk with five novel loci. Four loci are located in the human leukocyte antigen (HLA) region at 6p21.3, including two nonsynonymous variants (rs12614 [R32W] in complement factor B [CFB], Pmeta =1.28 × 10(-34) ; and rs422951 [T320A] in NOTCH4, Pmeta = 5.33 × 10(-16) ); one synonymous variant (rs378352 in HLA-DOA corresponding to HLA-DOA*010101, Pmeta = 1.04 × 10(-23) ); and one noncoding variant (rs2853953 near HLA-C, Pmeta = 5.06 × 10(-20) ). Another locus is located at 20q13.1 (rs1883832 in the Kozak sequence of CD40, Pmeta = 2.95 × 10(-15) ). Additionally, we validated seven of eight previously reported CHB susceptibility loci (rs3130542 at HLA-C, rs1419881 at TCF19, rs652888 at EHMT2, rs2856718 at HLA-DQB1, rs7453920 at HLA-DQB2, rs3077 at HLA-DPA1, and rs9277535 at HLA-DPA2, which are all located in the HLA region, 9.84 × 10(-71) ≤ Pmeta ≤ 9.92 × 10(-7) ). CONCLUSION: Our GWAS identified five novel susceptibility loci for CHB. These findings improve the understanding of CHB etiology and may provide new targets for prevention and treatment of this disease.

Interleukin-15 inhibits the expression of differentiation markers induced by Ca(2+) in keratinocytes.

Interleukin (IL)-15 is an important proinflammatory cytokine that can protect epidermal keratinocytes (KCs) from ultraviolet-induced apoptosis and plays a role in the pathogenesis of psoriasis. However, the impact of IL-15 on KC differentiation remains unknown. In this study, isolated human primary epidermal KCs were treated with various concentrations of IL-15 for different times, and the expression of differentiation markers (keratin 1, involucrin and loricrin) and p53 as well as the activation of ERK, AKT and Notch induced by IL-15 in the absence or presence of Ca(2+) was detected by real-time PCR and Western blot. The results showed that stimulation with Ca(2+) alone increased the expression of KC differentiation markers and p53 and promoted the activation of Notch1. Pretreatment with IL-15 resulted in a decrease in the Ca(2+) -induced expression of KC differentiation markers and p53. Additionally, Ca(2+) continually inhibited the phosphorylation of ERK1/2 and activated AKT, and IL-15 reduced the effect of Ca(2+) on ERK1/2 and AKT. FR180204, a specific inhibitor of ERK1/2 phosphorylation, slightly attenuated the effect of Ca(2+) on the expression of differentiation markers and p53 and the activation of Notch1. In contrast, MK-2206, an inhibitor of pAKT, strongly blocked the expression of the differentiation markers and p53 and the activation of Notch1. An anti-IL-15 antibody neutralized the effect of IL-15 on KC differentiation. These results indicate that IL-15 inhibits the Ca(2+) -induced differentiation of KCs, mainly via the attenuation of Ca(2+) -stimulated PI3K-AKT signalling.

Genome-wide copy number variation study in anorectal malformations.

Anorectal malformations (ARMs, congenital obstruction of the anal opening) are among the most common birth defects requiring surgical treatment (2-5/10 000 live-births) and carry significant chronic morbidity. ARMs present either as isolated or as part of the phenotypic spectrum of some chromosomal abnormalities or monogenic syndromes. The etiology is unknown. To assess the genetic contribution to ARMs, we investigated single-nucleotide polymorphisms and copy number variations (CNVs) at genome-wide scale. A total of 363 Han Chinese sporadic ARM patients and 4006 Han Chinese controls were included. Overall, we detected a 1.3-fold significant excess of rare CNVs in patients. Stratification of patients by presence/absence of other congenital anomalies showed that while syndromic ARM patients carried significantly longer rare duplications than controls (P = 0.049), non-syndromic patients were enriched with both rare deletions and duplications when compared with controls (P = 0.00031). Twelve chromosomal aberrations and 114 rare CNVs were observed in patients but not in 868 controls nor 11 943 healthy individuals from the Database of Genomic Variants. Importantly, these aberrations were observed in isolated ARM patients. Gene-based analysis revealed 79 genes interfered by CNVs in patients only. In particular, we identified a de novo DKK4 duplication. DKK4 is a member of the WNT signaling pathway which is involved in the development of the anorectal region. In mice, Wnt disruption results in ARMs. Our data suggest a role for rare CNVs not only in syndromic but also in isolated ARM patients and provide a list of plausible candidate genes for the disorder.

Genotypic variants at 2q33 and risk of esophageal squamous cell carcinoma in China: a meta-analysis of genome-wide association studies.

Genome-wide association studies have identified susceptibility loci for esophageal squamous cell carcinoma (ESCC). We conducted a meta-analysis of all single-nucleotide polymorphisms (SNPs) that showed nominally significant P-values in two previously published genome-wide scans that included a total of 2961 ESCC cases and 3400 controls. The meta-analysis revealed five SNPs at 2q33 with P< 5 × 10(-8), and the strongest signal was rs13016963, with a combined odds ratio (95% confidence interval) of 1.29 (1.19-1.40) and P= 7.63 × 10(-10). An imputation analysis of 4304 SNPs at 2q33 suggested a single association signal, and the strongest imputed SNP associations were similar to those from the genotyped SNPs. We conducted an ancestral recombination graph analysis with 53 SNPs to identify one or more haplotypes that harbor the variants directly responsible for the detected association signal. This showed that the five SNPs exist in a single haplotype along with 45 imputed SNPs in strong linkage disequilibrium, and the strongest candidate was rs10201587, one of the genotyped SNPs. Our meta-analysis found genome-wide significant SNPs at 2q33 that map to the CASP8/ALS2CR12/TRAK2 gene region. Variants in CASP8 have been extensively studied across a spectrum of cancers with mixed results. The locus we identified appears to be distinct from the widely studied rs3834129 and rs1045485 SNPs in CASP8. Future studies of esophageal and other cancers should focus on comprehensive sequencing of this 2q33 locus and functional analysis of rs13016963 and rs10201587 and other strongly correlated variants.

EZH2 genetic variants affect risk of gastric cancer in the Chinese Han population.

Enhancer of zeste 2 (EZH2) gene encodes a histone methyltransferase that constitutes the catalytic component of the polycomb repressive complex-2 (PRC2) to initiate epigenetic silencing of genes. It is reported that the expression level of EZH2 in gastric cancer tissue was highly correlated with tumor progression, however, whether EZH2 genetic variants were associated with the risk of gastric cancer remains yet unknown. In this study, we conducted a genotyping analysis for EZH2 in 311 cases of gastric cancer and 425 controls from the Chinese Han population. We found five single nucleotide polymorphisms (SNP; rs12670401, rs6464926, rs2072407, rs734005, and rs734004) of EZH2 gene were significantly associated with the risk of gastric cancer. Of which, the rs12670401 with the minor allele C and rs6464926 with the minor allele T revealed strong associations with increased gastric cancer risk [P = 0.009, adjusted odds ratio (aOR) = 1.327, 95% CI = 1.075-1.683 and P = 0.012, aOR = 1.310, 95% CI = 1.059-1.619]. The other three SNPs, rs2072407, rs734005, and rs734004 contributed to significantly reduced risk of gastric cancer (P = 0.033, aOR = 0.787, 95% CI = 0.633-0.981, P = 0.045, aOR = 0.799, 95% CI = 0.642-0.995 and P = 0.048, aOR = 0.803, 95% CI = 0.645-0.999), respectively. We further found that rs12670401 and rs6464926 were in a strong LD while rs2072407, rs734005, and rs734004 were in another. Haplotype analysis of the five SNPs showed that haplotype CCTCT reduced the risk of gastric cancer (P = 0.031 and aOR = 0.784), while haplotype GTCTC significantly elevated the risk of gastric cancer (P = 0.011 and aOR = 1.310). We concluded that EZH2 variants were significantly associated with gastric cancer risk. Our results for the first time provided new insight into susceptibility factors of EZH2 gene variants in carcinogenesis of gastric cancer of the Chinese Han population.

Association analyses identifying two common susceptibility loci shared by psoriasis and systemic lupus erythematosus in the Chinese Han population.

BACKGROUND: Genome-wide association studies (GWASs) have revealed a large number of genetic risk loci for many autoimmune diseases. One clear finding emerging from the published genetic studies of autoimmunity is that different autoimmune diseases, such as psoriasis and systemic lupus erythematosus (SLE), share susceptibility loci. Our study explores additional susceptibility loci shared by psoriasis and SLE in the Chinese Han population. METHODS: In total, 20 single nucleotide polymorphisms (SNPs) in 17 previously reported psoriasis susceptibility loci and 34 SNPs from 24 previously reported SLE susceptibility loci were investigated in our initial psoriasis and SLE GWAS dataset. Among these SNPs, we selected two SNPs (rs8016947 and rs4649203) with association values of p<5×10(-2) for both diseases in the GWAS data for further investigation in psoriasis (7260 cases and 9842 controls) and SLE (2207 cases and 9842 controls) using a Sequenom MassARRAY system. RESULTS: We found that these two SNPs (rs8016947 and rs4649203) in two loci (NFKBIA and IL28RA) were associated with psoriasis and SLE with genome-wide significance (Pcombined<5×10(-8) in psoriasis and Pcombined<5×10(-8) in SLE): rs8016947 at NFKBIA (Pcombined-psoriasis=3.90×10(-10), Pcombined-SLE=1.08×10(-13)) and rs4649203 at IL28RA (Pcombined-psoriasis=3.91×10(-12), Pcombined-SLE=9.90×10(-9)). CONCLUSIONS: These results showed that two common susceptibility loci (NFKBIA and IL28RA) are shared by psoriasis and SLE in the Chinese Han population.

Variants in TNFSF4, TNFAIP3, TNIP1, BLK, SLC15A4 and UBE2L3 interact to confer risk of systemic lupus erythematosus in Chinese population.

Our previous genome-wide association studies on SLE have identified several susceptibility genes involved in NF-κB signaling pathway, including TNFSF4, TNFAIP3, TNIP1, BLK, SLC15A4 and UBE2L3. The aim of this study is to investigate the association model (additive, dominant, recessive) of these genes and search for possible gene-gene interactions between them. In this study, we explored the association model of these six genes and search for possible gene-gene interactions based on identified single-nucleotide polymorphisms (SNPs) among them by using logistic regression analysis in the combined sample of 4,199 cases and 8,255 controls. The most significant association evidence was observed under recessive model for all of these SNPs. Besides, significant interactions between these SNPs were observed in this study: the TNFSF4 and TNIP1 SNPs (P adjusted = 1.68E-10), the TNFSF4 and SLC15A4 SNPs (P adjusted = 3.55E-08), the TNFSF4 and UBE2L3 SNPs (P adjusted = 8.74E-13), the TNIP1 and BLK SNPs (P adjusted = 9.45E-10), the TNIP1 and UBE2L3 SNPs (P adjusted = 8.25E-11), the TNFAIP3 and UBE2L3 SNPs (P adjusted = 3.06E-14) and the BLK and SLC15A4 SNPs (P adjusted = 4.51E-12). These results may contribute to our understanding of SLE genetic interactions and account for the additional risk of certain patients to develop SLE.

The association between a single nucleotide polymorphism rs11966200 in MHC region and clinical features of generalized vitiligo in Chinese Han population.

Vitiligo is an acquired pigmentary disorder characterized by loss of epidermal melanocytes. A strong association at a single nucleotide polymorphism (SNP) rs11966200 within MHC region had been identified in a recent genome-wide association study of generalized vitiligo in Chinese Han population. This study aims to investigate the relationships between SNP rs11966200 and the clinical features of generalized vitiligo in Chinese Han population. We compared the allele and genotype frequency among different vitiligo subphenotypes including age onset, extent of disease, clinical subtypes, family history of vitiligo and history of autoimmune disease. Our data showed SNP rs11966200 was associated with early-onset vitiligo (onset age ≤ 20 years) (odds ratio [OR], 1.54; p = 2.01 × 10(-13)), moderate-severe vitiligo (involved body surface ≥ 5 %) (OR, 1.17; p = 0.025), vitiligo vulgaris (OR, 1.13; p = 0.043), and focal vitiligo (OR, 0.86; p = 0.018). The study suggested that the underlying risk causal allele tagged by SNP rs11966200 might not only play important roles in the development of vitiligo, but also contribute to the diverse clinical characteristics of generalized vitiligo at least in Chinese Han population.

Exome sequencing identified a missense mutation of EPS8L3 in Marie Unna hereditary hypotrichosis.

BACKGROUND: Marie Unna hereditary hypotrichosis (MUHH) is an autosomal dominant disorder characterised by coarse, wiry, twisted hair developed in early childhood and subsequent progressive hair loss. MUHH is a genetically heterogeneous disorder. No gene in 1p21.1-1q21.3 region responsible for MUHH has been identified. METHODS: Exome sequencing was performed on two affected subjects, who had normal vertex hair and modest alopecia, and one unaffected individual from a four-generation MUHH family of which our previous linkage study mapped the MUHH locus on chromosome 1p21.1-1q21.3. RESULTS: We identified a missense mutation in EPS8L3 (NM_024526.3: exon2: c.22G->A:p.Ala8Thr) within 1p21.1-1q21.3. Sanger sequencing confirmed the cosegregation of this mutation with the disease phenotype in the family by demonstrating the presence of the heterozygous mutation in all the eight affected and absence in all the seven unaffected individuals. This mutation was found to be absent in 676 unrelated healthy controls and 781 patients of other disease from another unpublished project of our group. CONCLUSIONS: Taken together, our results suggest that EPS8L3 is a causative gene for MUHH, which was helpful for advancing us on understanding of the pathogenesis of MUHH. Our study also has further demonstrated the effectiveness of combining exome sequencing with linkage information for identifying Mendelian disease genes.

Exome sequencing identifies a COL14A1 mutation in a large Chinese pedigree with punctate palmoplantar keratoderma.

BACKGROUND: Punctate palmoplantar keratoderma (PPPK) is a rare autosomal dominant skin disorder characterised by numerous hyperkeratotic papules irregularly distributed on the palms and soles. To date, no causal gene for this disease has been identified. METHODS: We performed exome sequencing analysis of four affected individuals and two unaffected controls from one Chinese PPPK family where disease locus was mapped at 8q24.13-8q24.21 by our previous linkage analysis. RESULTS: We identified a novel heterozygous mutation in COL14A1 gene (c.4505C→T (p.Pro1502Leu)), which located within the linkage region that we previously identified for PPPK. The mutation was shared by the four affected individuals, but not for the two controls of the family. Sanger sequencing confirmed this mutation in another four cases from this family. This mutation was invisible in the normal controls of this family as well as the additional 676 unrelated normal controls and 781 patients with other disease. The shared COL14A1 mutation, p.Pro1502Leu, is a missense substitution at a highly conserved amino acid residue across multiple species. CONCLUSIONS: The power of combining exome sequencing and linkage information in the study of genetics of autosomal dominant disorders, even in simplex cases, has been demonstrated. Our results suggested that COL14A1 would be a casual gene for PPPK, which was helpful for advancing us on understanding of the pathogenesis of PPPK.

One novel susceptibility locus associate with systemic lupus erythematosus in Chinese Han population.

The aim of the study is to explore additional susceptibility factors for systemic lupus erythematosus (SLE) in Chinese Hans. Based on our previous GWAS of SLE, we performed a multistage replication study involving 3,152 cases and 7,050 controls from China to identify additional susceptibility loci for SLE by using the Sequenom MassArray system. All Chinese Han samples used in this study were obtained from doctors through collaboration with multiple hospitals in two geographic regions (central and southern China). Single-marker association analyses were performed using logistic regression with gender as a covariate in each case-control cohort. The joint analysis of all combined samples was performed using logistic regression with gender and sample cohorts as covariates. The significant association evidence for rs906868 (OR = 1.14, 95% CI 1.08-1.20, P combined = 7.71 × 10(-10)) and rs7579944 (OR = 1.13, 95% CI 1.07-1.19, P combined = 5.55 × 10(-9)) was observed, which located at 2p23.1. In this region, limb bud and heart development homolog (LBH) was the only gene indicated, suggesting LBH might be a susceptibility gene for SLE, although its function was still unknown. The results indicated that the SNP rs7579944, rs906868 at 2p23.1 showed significant association with SLE. The genes LBH which located in this loci might be the predisposing genes of SLE.

Genomewide association study of leprosy.

BACKGROUND: The narrow host range of Mycobacterium leprae and the fact that it is refractory to growth in culture has limited research on and the biologic understanding of leprosy. Host genetic factors are thought to influence susceptibility to infection as well as disease progression. METHODS: We performed a two-stage genomewide association study by genotyping 706 patients and 1225 controls using the Human610-Quad BeadChip (Illumina). We then tested three independent replication sets for an association between the presence of leprosy and 93 single-nucleotide polymorphisms (SNPs) that were most strongly associated with the disease in the genomewide association study. Together, these replication sets comprised 3254 patients and 5955 controls. We also carried out tests of heterogeneity of the associations (or lack thereof) between these 93 SNPs and disease, stratified according to clinical subtype (multibacillary vs. paucibacillary). RESULTS: We observed a significant association (P<1.00x10(-10)) between SNPs in the genes CCDC122, C13orf31, NOD2, TNFSF15, HLA-DR, and RIPK2 and a trend toward an association (P=5.10x10(-5)) with a SNP in LRRK2. The associations between the SNPs in C13orf31, LRRK2, NOD2, and RIPK2 and multibacillary leprosy were stronger than the associations between these SNPs and paucibacillary leprosy. CONCLUSIONS: Variants of genes in the NOD2-mediated signaling pathway (which regulates the innate immune response) are associated with susceptibility to infection with M. leprae.

Multiple Loci within the major histocompatibility complex confer risk of psoriasis.

Psoriasis is a common inflammatory skin disease characterized by thickened scaly red plaques. Previously we have performed a genome-wide association study (GWAS) on psoriasis with 1,359 cases and 1,400 controls, which were genotyped for 447,249 SNPs. The most significant finding was for SNP rs12191877, which is in tight linkage disequilibrium with HLA-Cw*0602, the consensus risk allele for psoriasis. However, it is not known whether there are other psoriasis loci within the MHC in addition to HLA-C. In the present study, we searched for additional susceptibility loci within the human leukocyte antigen (HLA) region through in-depth analyses of the GWAS data; then, we followed up our findings in an independent Han Chinese 1,139 psoriasis cases and 1,132 controls. Using the phased CEPH dataset as a reference, we imputed the HLA-Cw*0602 in all samples with high accuracy. The association of the imputed HLA-Cw*0602 dosage with disease was much stronger than that of the most significantly associated SNP, rs12191877. Adjusting for HLA-Cw*0602, there were two remaining association signals: one demonstrated by rs2073048 (p = 2 x 10(-6), OR = 0.66), located within c6orf10, a potential downstream effecter of TNF-alpha, and one indicated by rs13437088 (p = 9 x 10(-6), OR = 1.3), located 30 kb centromeric of HLA-B and 16 kb telomeric of MICA. When HLA-Cw*0602, rs2073048, and rs13437088 were all included in a logistic regression model, each of them was significantly associated with disease (p = 3 x 10(-47), 6 x 10(-8), and 3 x 10(-7), respectively). Both putative loci were also significantly associated in the Han Chinese samples after controlling for the imputed HLA-Cw*0602. A detailed analysis of HLA-B in both populations demonstrated that HLA-B*57 was associated with an increased risk of psoriasis and HLA-B*40 a decreased risk, independently of HLA-Cw*0602 and the C6orf10 locus, suggesting the potential pathogenic involvement of HLA-B. These results demonstrate that there are at least two additional loci within the MHC conferring risk of psoriasis.

A miRNA-492 binding-site polymorphism in BSG (basigin) confers risk to psoriasis in central south Chinese population.

Psoriasis (PS; MIM#177900) is a chronic inflammatory immune-mediated skin disorder. Although the disease is believed to be caused by a combination of genetic, immunologic and environmental factors, its complete etiology has not been fully understood. Here, we focused on the BSG (MIM#109480), a member of the immunoglobulin superfamily expressed ubiquitously in circulating immune cell populations. We observed that the expression level of BSG in PBMCs was elevated in psoriasis patients. To understand the underlying mechanism for this change, we genotyped the rs8259 T>A SNP located in the 3'UTR of the BSG gene from 668 psoriasis patients and 1,143 healthy controls. The rs8259 T allele was associated with significantly decreased psoriasis susceptibility (OR = 0.758, 95% CI 0.638-0.901, p = 0.002). Interestingly, the rs8259 polymorphism was located in a seed region for miR-492 binding. The miR-492 was able to bind to the BSG 3'UTR sequence bearing the rs8259 T allele as assayed by luciferase reporter gene assay. The substitution of T with A abolished miR-492 binding. BSG protein expression in PBMCs from patients carrying the rs8259 AA genotype was significantly higher than in those from patients carrying the rs8259 TT genotype. Our study suggests that miR-492 may physiologically suppress BSG expression and the BSG rs8259 polymorphism is associated with decreased psoriasis susceptibility through affecting miR-492 binding.

Follow-up study identifies two novel susceptibility loci PRKCB and 8p11.21 for systemic lupus erythematosus.

OBJECTIVE: We have performed a large-scale replication study based on our previous genome-wide association study (GWAS) of SLE in the Chinese Han population to further explore additional genetic variants affecting susceptibility to SLE. METHODS: Thirty-eight single nucleotide polymorphisms from our GWAS were genotyped in two additional Chinese Han cohorts (total 3152 cases and 7050 controls) using the Sequenom Massarray system. Association analyses were performed using logistic regression with gender or sample cohorts as a covariate. RESULTS: Association evidence for rs16972959 (PRKCB at 16p11.2) and rs12676482 (8p11.21) with SLE was replicated independently in both replication cohorts (P < 0.05), showing high significance for SLE in combined all 4199 cases and 8255 controls of Chinese Han [rs16972959: odds ratio (OR) = 0.81; 95% CI 0.76, 0.87; P(combined) = 1.35 × 10(-9); rs12676482: OR = 1.26; 95% CI 1.15, 1.38; P(combined) = 6.68 × 10(-7)). PRKCB is related to the established SLE immune-related pathway (NF-κB) and 8p11.21 contains important candidate genes such as IKBKB and DKK4. IKBKB is a critical component of NF-κB and DKK4 is an inhibitor of canonical Wnt signalling pathway. Interestingly, PRKCB is required for recruiting IKBKB into lipid rafts, up-regulating NF-κB-dependent survival signal. CONCLUSIONS: Our findings provided novel insights into the genetic architecture of SLE and emphasized the contribution of multiple variants of modest effect. Further study focused on PRKCB, 8p11.21, should advance our understanding on the pathogenesis of SLE.

A single-nucleotide polymorphism of the TNFSF4 gene is associated with systemic lupus erythematosus in Chinese Han population.

Systemic lupus erythematosus (SLE) is a prototypic autoimmune disease with complex genetic inheritance. Recently, single-nucleotide polymorphisms (SNPs) in tumor necrosis factor (TNF) superfamily gene TNFSF4 have been shown to be associated with SLE in European and Hong Kong Chinese populations. But it is unknown whether it is also associated with the disease in Mainland Chinese Han population. We genotyped the SNPs rs1234315 near the TNFSF4 gene in 1,344 SLE patients and 4,315 controls of Chinese Han population and confirmed the association between the SNP and the SLE [odds ratios (ORs) of 1.45 and P values of 1.5 × 10(-16)]. The stratification analyses showed that rs1234315 was more strongly associated with SLE patients with arthritis. Our study not only suggested that the TNFSF4 gene was associated with SLE in Chinese Han population, but also implied that it might be a common genetic factor predisposing to the development of SLE in multiple populations.

Fine mapping of the psoriasis susceptibility locus PSORS1 supports HLA-C as the susceptibility gene in the Han Chinese population.

PSORS1 (psoriasis susceptibility gene 1) is a major susceptibility locus for psoriasis. Several fine-mapping studies have highlighted a 300-kb candidate region of PSORS1 where multiple biologically plausible candidate genes were suggested. The most recent study has indicated HLA-Cw6 as the primary PSORS1 risk allele within the candidate region in a Caucasian population. In this study, a family-based association analysis of the PSORS1 locus was performed by analyzing 10 polymorphic microsatellite markers from the PSORS1 region as well as HLA-B, HLA-C and CDSN loci in 163 Chinese families of psoriasis. Five marker loci show strong evidence (P<10(-3)), and one marker locus shows weak evidence (P = 0.04) for association. The haplotype cluster analysis showed that all the risk haplotypes are Cw6 positive and share a 369-kb region of homologous marker alleles which carries all the risk alleles, including HLA-Cw6 and CDSN*TTC, identified in this study. The recombinant haplotype analysis of the HLA-Cw6 and CDSN*TTC alleles in 228 Chinese families showed that the HLA-Cw6(-)/CDSN*TTC(+) recombinant haplotype is clearly not associated with risk for psoriasis (TratioNT = 29:57, p = 0.0025) in a Chinese population, suggesting that the CDSN*TTC allele itself does not confer risk without the presence of the HLA-Cw6 allele. The further exclusion analysis of the non-risk HLA-Cw6(-)/CDSN*TTC(+) recombinant haplotypes with common recombination breakpoints has allowed us to refine the location of PSORS1 to a small candidate region. Finally, we performed a conditional linkage analysis and showed that the HLA-Cw6 is a major risk allele but does not explain the full linkage evidence of the PSORS1 locus in a Chinese population. By performing a series of family-based association analyses of haplotypes as well as an exclusion analysis of recombinant haplotypes, we were able to refine the PSORS1 gene to a small critical region where HLA-C is a strong candidate to be the PSORS1 susceptibility gene.

A Common Variant at 11q23.3 Is Associated with Susceptibility to Atopic Dermatitis in the Han Chinese Population.

Background: Genome-wide association studies (GWASs) have identified many genetic variants that are risk factors for numerous immune-mediated diseases. In particular, different immune-mediated diseases have been found to share the same susceptibility loci. Therefore, exploring the genetic overlap between atopic dermatitis (AD) and other immune-mediated diseases in more detail may help identify additional shared susceptibility loci among common immune-mediated diseases. Recent evidence suggests that the 11q23.3 locus is a susceptibility locus shared among multiple immune-mediated diseases. Objective: This study was designed to investigated whether SNPs at the chromosome 11q23.3 locus are associated with AD in the Han Chinese population. Methods: In total, 16 SNPs within the 11q23.3 locus were genotyped using TaqMan assays for 1,012 AD cases and 1,362 controls. From these SNPs, we selected rs638893 with an association values of p < 5 × 10-2 for AD for further analysis in an independent replication study using the Sequenom MassARRAY system to genotype an additional (consisting of 1,288 cases and 1,380 controls). The combined analyses were performed in two stages using a meta-analytical method. Results: We identified a common variant at 11q23.3 (rs638893), that was significantly associated (p = 1.58 × 10-3, OR = 1.22) with AD. The genotype-based association analysis revealed that the recessive model provided the best fit for rs638893. Conclusion: Our study identified a variant on chromosome 11q23.3 that likely confers susceptibility to AD, thereby advancing our understanding of the genetic basis of this disease.

A single-nucleotide polymorphism of the TNFAIP3 gene is associated with systemic lupus erythematosus in Chinese Han population.

Systemic lupus erythematosus (SLE) is a complex systemic disease influenced by genetic and environmental factors. The exact pathogenesis of SLE is still unknown. Recently, several genome-wide association studies (GWA) in European population have found many novel susceptibility genes for SLE including TNFAIP3. In order to examine whether TNFAIP3 is associated with SLE in Chinese Han population, we genotyped one of its non-synonymous mutation SNP rs2230926, showing significant association evidence with SLE in European population, with 1,420 cases and 4,461 controls of Chinese Han by using Sequenom MassArray system. Highly significant association between SNP rs2230926 and SLE of Chinese Han was detected [OR = 1.65, 95% confidence interval (CI): 1.392-1.986, P = 2.03 x 10(-8)]. Interestingly, rs2230926 of TNFAIP3 was also associated with arthritis, ANA and some other subphenotypes of the disease. Our findings suggest that SNP rs2230926 in the TNFAIP3 might be a common genetic factor for SLE within different populations in terms of Chinese Han and European population.

Genetic diagnosis in a Chinese Hailey-Hailey disease pedigree with novel ATP2C1 gene mutation.

Hailey-Hailey disease (HHD) is an autosomal dominant skin disorder characterized by recurrent eruption of vesicles and bullae at the sites of friction and in the intertriginous areas. Mutations in the ATP2C1 gene encoding the human secretory pathway calcium ATPase 1 (hSPCA1) have been identified as the causative mutations in HHD. In this study, we used direct sequencing and restriction endonuclease digestion to analyze mutations of the ATP2C1 gene in a Chinese three-generation pedigree. A heterozygous T-to-C transition at nucleotide 1004 in exon 12 of ATP2C1 gene was detected. After summarizing the reported cases with ATP2C1 mutation, we concluded that the T1004C transition resulted in a novel missense mutation of leucine condon (CTG) to proline (CCG) at amino acid residue 335(L335P) in hSPCA1. Here, a genetic diagnosis was made for the proband's daughter before the clinical presentation. The study realized the molecular diagnosis in the HHD pedigree. Our findings should be useful for genetic counseling and prenatal diagnosis for the affected family and in demonstrating the critical role of the ATP2C1 gene in the pathogenesis of HHD further.