Interleukin-13 gene polymorphism G4257A is associated with atopic dermatitis in Japanese patients

Interleukin (IL)-13 plays an important role in the induction of immunoglobulin E (IgE) and in the pathogenesis of atopic dermatitis (AD). We investigated the allele and genotype frequencies of three IL-13 single nucleotide polymorphisms (SNPs) (A704C and C1103T in the promoter region and G4257A in exon 4) in Japanese patients with AD. For A704C and C1103T SNPs, there were no significant differences in allele or genotype frequencies between AD patients and controls. For G4257A SNP, A allele was significantly increased in AD patients (39.5%) compared with controls (29.4%) (P = 0.016). The same proportion of each genotype and allele was observed in the patient subgroup with and without asthma. Serum IgE levels and peripheral eosinophil counts were not significantly different among genotypes in G4257A SNP. There was also no significant difference in allele or genotype frequencies between AD patients with mild disease and those with severe disease, between those with family history of AD and those without it, or between those with family history of atopic disorders and those without it. This result suggests that 4257A allele is associated with susceptibility to AD and that it may function in the pathogenesis of AD itself, presumably by other mechanisms than inducing IgE production.     

Analysis of GM-CSF gene polymorphisms (3606T/C and 3928C/T) in Japanese patients with atopic dermatitis

Granulocyte-macrophage colony-stimulating factor (GM-CSF) is thought to play an important role in the pathogenesis of atopic dermatitis. To examine whether GM-CSF single nucleotide polymorphisms (SNPs) are associated with susceptibility to atopic dermatitis, we investigated the genotype and allele frequencies of the SNPs 3606T/C and 3928C/T of the GM-CSF gene in 181 Japanese patients with atopic dermatitis and 100 controls, using a PCR restriction fragment length polymorphism method. A strong linkage disequilibrium existed between the polymorphisms 3606 and 3928, suggesting two common GM-CSF haplotypes, 3606*T-3928*C and 3606*C-3928*T. However, there was no significant difference in genotype or allele frequencies between patients with atopic dermatitis and controls for either of the two polymorphisms, thus GM-CSF SNPs do not appear to be associated with susceptibility to atopic dermatitis in Japanese patients. A large-scale study is necessary to confirm these findings.     

The -431C>T polymorphism of thymus and activation-regulated chemokine increases the promoter activity but is not associated with susceptibility to atopic dermatitis in Japanese patients

BACKGROUND: Thymus and activation-regulated chemokine (TARC) plays an important role in the pathogenesis of atopic dermatitis (AD). We recently detected the single nucleotide polymorphism (SNP) (-431C>T) in the 5'-flanking region of TARC gene. OBJECTIVES: To examine whether the -431C>T SNP of the TARC gene is associated with susceptibility to AD and whether it affects the promoter activity of the TARC gene. METHODS: We investigated the genotype and allele frequencies of the SNP in 193 AD patients and 158 healthy controls by polymerase chain reaction-restriction fragment length polymorphism method. We compared the promoter activities between TARC promoter carrying 431C and that carrying -431T by transient-transfection assay in DJM-1 cell line. RESULTS: There were no significant differences in genotype or allele frequencies between AD patients and controls (genotype: P = 0.38, allele: P = 0.22). Luciferase activity was higher in -431T constructs than in -431C constructs (2.3-fold, P = 9.5 x 10(-6)). CONCLUSION: These results suggest that the -431C>T SNP of the TARC gene enhances the promoter activity of TARC gene but is not associated with susceptibility to AD in Japanese population.     

Eotaxin gene single nucleotide polymorphisms in the promoter and exon regions are not associated with susceptibility to atopic dermatitis,but two of them in the promoter region are associated with serum IgE levels in patients with atopic dermatitis

Eotaxin is believed to play an important role in atopic dermatitis (AD) as a potent chemoattractant and activator of eosinophils and Th2 lymphocytes. The eotaxin gene is located at chromosome 17q21.1-q21.2, and linkage findings of AD on chromosome 17 were reported. Recently we have identified single nucleotide polymorphisms (SNPs) of eotaxin gene (-426C > T, -384A > G, 67G > A). To learn whether eotaxin gene SNPs are associated with susceptibility to AD or phenotypes of AD, we investigated the genotype frequencies at each SNP of the gene in AD patients and in controls. We examined 140 Japanese AD patients and 140 healthy Japanese individuals. Genotyping was performed using the polymerase chain reaction-restriction fragment length polymorphism method. No significant difference was observed in allele or genotype frequencies of any SNP between AD patients and controls. Serum immunoglobulin E (IgE) levels were significantly lower in CT and TT genotype than in CC (P = 0.038) in -426C > T SNP, and lower in GG than in AA and AG with borderline significance (P = 0.053) in -384A > G SNP in AD patients. Eotaxin gene SNPs in the promoter and exon regions are not associated with susceptibility to AD, but two of them in the promoter region are associated with phenotype of AD.     

Interleukin-12 p40 gene (IL12B) 3'-untranslated region polymorphism is associated with susceptibility to atopic dermatitis and psoriasis vulgaris

Interleukin-12 (IL-12) is believed to play an important role in inducing Th1-type cytokine profiles. Atopic dermatitis (AD) and psoriasis vulgaris (PsV) are considered to be Th2 and Th1 type disease, respectively. The IL-12 p40 subunit gene (IL12B) is located at chromosome 5q31-33 and linkage findings of AD on 5q31 were reported. Recently single nucleotide polymorphism (SNP) (1188A/C) of IL12B has been reported. In function, it has been reported that this SNP is associated with IL12B mRNA expression levels. To learn whether this SNP is associated with susceptibility to AD or PsV, we investigated the genotype and allele frequencies of the SNP in AD patients, in PsV patients and in controls, examining 164 AD patients, 143 PsV patients and 100 healthy individuals in Japanese population. Genotyping was performed using the polymerase chain reaction-restriction fragment length polymorphism method. The A allele was decreased in AD patients (40.9%, p = 0.031) and increased in PsV patients (60.1%, p = 0.035) compared with controls (50.5%). This suggests that IL12B SNP is associated with susceptibility to AD and PsV, presumably by affecting the Th1/Th2 balance.     

Lack of association between the promoter polymorphisms at positions -308 and -238 of the tumor necrosis factor alpha gene and psoriasis vulgaris in Japanese patients

BACKGROUND: Psoriasis features an increased level and activity of tumor necrosis factor alpha (TNF-alpha). The TNF-alpha gene has single nucleotide polymorphisms (SNPs) at positions -308 (-308G>A) and -238 (-238G>A) in the promoter region, and the -238G>A SNP has been reported to be associated with psoriasis vulgaris (PV) and psoriatic arthritis in Caucasians. OBJECTIVE: To examine whether these SNPs are associated with susceptibility to PV in Japanese patients, we investigated the genotype and allele frequencies at each SNP in Japanese PV patients and in controls. METHODS: We examined 163 PV patients and 96 healthy individuals. Genotyping was performed using the polymerase chain reaction-restriction fragment length polymorphism method. RESULTS: No significant association between the genotypes or alleles of these SNPs and susceptibility to PV was observed. CONCLUSION: These SNPs themselves are not associated with susceptibility to PV in the Japanese.     

白介素12B基因rs6887695多态性与汉族人寻常性银屑病临床表型的相关性

目的 探讨白介素12B（IL-12B）基因多态性位点rs6887695与汉族人寻常性银屑病临床表型（发病年龄、家族史、临床类型、性别）的相关性。 方法　采用ABI Taqman探针荧光PCR技术,对575例寻常性银屑病患者和1403例健康对照的DNA样本进行IL-12B基因多态位点rs6887695的基因分型。使用SPSS14.0分析软件,χ2检验比较患者组和健康对照组间、不同临床表型组间的基因型和等位基因频率分布的差异性。 结果 IL-12B基因多态性位点rs6887695三种基因型（GG、GC、CC）频率在寻常性银屑病患者组分别为42.61%、45.39%和12.0%,健康对照组分别为34.42%、47.83%和17.75%;等位基因频率（G、C）患者组分别为65.30%和34.70%,健康对照组分别为58.34%和41.66%,基因型和等位基因频率分布在患者组和健康对照组间差异均有统计学意义（χ2值分别为16.31和16.54,P值均 < 0.01）,在慢性斑块状（543例）和急性滴状银屑病患者（32例）组间的差异均有统计学意义（χ2值分别为18.11和12.19,P值均 < 0.01）。等位基因G和基因型GG在患者组中的频率明显高于健康对照组,等位基因G和基因型GG在斑块状患者中的频率高于滴状患者。少儿发病组（35例）与成人发病组（540例）、家族史阳性组（102例）与家族史阴性组（440例）、男性患者组（341例）与女性患者组（234例）的基因型和等位基因频率分布差异均无统计学意义（P值均 > 0.05）。 结论 IL-12B（rs6887695）基因多态性与汉族人寻常性银屑病易感性相关联,特别是与斑块状银屑病相关,但与患者的发病年龄、家族史及性别可能无关联。     

Investigation of the eotaxin gene -426C-->T, -384A-->G and 67G-->a single-nucleotide polymorphisms and atopic dermatitis in Italian children using family-based association methods.

BACKGROUND: Eotaxin plays an important role in atopic dermatitis (AD) as a potent chemoattractant and activator of eosinophils and T-helper 2 lymphocytes. AIM: To investigate whether single-nucleotide polymorphisms of the eotaxin gene are associated with AD, we investigated the genotype and allelic frequencies of -426C-->T, -384A-->G, and 67G-->A SNPs in 130 Italian families. METHODS: In total, 130 children with either the extrinsic allergic or intrinsic nonallergic forms of AD (EAD and IAD) were recruited from 130 families. Genotyping was performed using PCR and restriction fragment length polymorphism analysis. RESULTS: A significant difference was observed in the genotype frequency of the -426C-->T SNP between children with EAD and those with IAD (P = 0.01), and between children with EAD and controls (P = 0.01). The allele frequencies of the -426C-->T SNP were significantly different between children with EAD and those with IAD (P < 0.01), and between children with EAD and controls (P < 0.01). For children with EAD, the genotype frequency of the -426C-->T SNP was no different between the groups with mild, moderate and severe SCORAD (P = NS). No significant association was observed between the -384A-->G and 67G-->A SNPs and the two groups of children with EAD and IAD compared with the control group. In 32 trios selected from 68 EAD families, the transmission disequilibrium test showed a preferential transmission of the -426T allele from the parents to affected offspring (P < 0.01). CONCLUSIONS: Our results suggest that in our group of children with AD, the eotaxin gene may play a crucial role in the development of extrinsic AD, probably with other genetic factors.     

Human arylamine N-acetyltransferase 2 polymorphism and susceptibility to allergic contact dermatitis

BACKGROUND: N-acetyltransferase 2 (NAT2) polymorphism may be involved in the pathogenesis of allergic contact dermatitis. OBJECTIVE: The present study was designed to evaluate whether acetylation polymorphism plays a role in the susceptibility to p-Phenylenediamine (PPD) sensitization. METHODS: The frequencies of seven NAT2 point mutations, namely G191A, C282T, T341C, C481T, G590A, A803G, and G857A, and genotypes were determined by PCR/RFLP in a total of 70 patients with allergic contact dermatitis to PPD and 100 control subjects with no history of allergy, atopy, lung disease, diabetes mellitus and cancer. RESULTS: Genotypes coding rapid acetylation were detected in 52.9% and 37.0% of patients with contact dermatitis and control subjects, respectively (P = 0.04). The frequency of the NAT2*4 allele and NAT2*4/*4 genotype, coding for rapid acetylation, were also significantly higher in the contact dermatitis patients than in the control subjects (P = 0.003). CONCLUSION: Our results suggest an association between rapid acetylation polymorphism and susceptibility to PPD sensitization.     

广西壮族、汉族系统性红斑狼疮与Toll样受体9基因多态性研究

目的 探讨TLR9单核苷酸多态性与广西系统性红斑狼疮（SLE）患者发病的相关性,以及其在壮族、汉两个民族间的差异。 方法 聚合酶链反应-限制性酶切技术、聚合酶链反应-限制性片段长度多态性分析技术（PCR-RFLP）对97例广西SLE患者和202例广西健康对照者的TLR9基因多态性进行检测,分析其基因型和等位基因频率与SLE部分临床实验室指标的关联性,并比较两民族间的差异。 结果 TLR9 rs352140CC、CT、TT基因型频率在汉族SLE组与汉族对照组中分别为42.9%、41.1%、16.1%和38.3%、55.8%、5.8%,差异有统计学意义（P < 0.05）,其C、T等位基因频率差异无统计学意义（P > 0.05）。TLR9rs352140 C/T基因型频率和等位基因频率在壮族SLE组与壮族健康对照组间、壮族SLE组与汉族SLE组间差异无统计学意义（均P > 0.05）。TLR9 rs352140TT基因型频率在ds-DNA阳性组比阴性组高（P < 0.05）,而T等位基因频率在两组间差异无统计学意义（P > 0.05）。TLR9 rs352140TT基因型频率和T等位基因的频率在SLEDAI ≥ 9组比SLEDAI < 9组高,差异有统计学意义（均P < 0.05）。TLR9 rs352140TT基因型频率和T等位基因的频率在ANA阳性组与阴性组间差异无统计学意义（均P > 0.05）。 结论 TLR9 rs352140基因多态性可能与广西汉族人SLE的易感性有关, TLR9基因多态性与部分SLE指标可能具有相关性。     

CC chemokine receptor 4 expression on peripheral blood CD4+ T cells reflects disease activity of atopic dermatitis

Recent studies indicate that Th1 and Th2 cells differ in their chemokine receptor expression and their responsiveness to various chemokines. Therefore, selective Th2 cell recruitment in Th2-predominant inflammatory diseases such as atopic dermatitis may be under the influence of some chemokines. It is reported that CC chemokine receptor (CCR) 4 is selectively expressed on Th2 cells whereas CXC chemokine receptor (CXCR) 3 is selectively expressed on Th1 cells. In this study we examined CCR4 and CXCR3 expression on peripheral blood CD4+ and CD8+ T cells obtained from adult atopic dermatitis subjects, and compared the results with those from patients with psoriasis vulgaris and healthy controls. CCR4 was preferentially expressed on CD4+ T cells from atopic dermatitis subjects and CXCR3 was preferentially expressed on CD4+ T cells from psoriasis vulgaris subjects. This CCR4 expression was prominent especially in severe atopic dermatitis subjects. CCR4 expression on CD4+ T cells in severe atopic dermatitis subjects decreased on improvement of disease activity. CD25 was preferentially expressed on CCR4+CD4+ T cells but not on CXCR3+CD4+ T cells in atopic dermatitis subjects. Cutaneous lymphocyte-associated antigen was also preferentially expressed on CCR4+CD4+ T cells but not on CXCR3+CD4+ T cells in atopic dermatitis subjects. CD4+ T cells in atopic dermatitis skin lesions were predominantly CCR4+ cells. Taken together, this study strongly indicates that CCR4+CD4+ T cells reflect disease activity and suggests that CCR4 expression is important for T cell infiltration into atopic dermatitis lesions. Thus, CCR4 may be a possible target for therapy of atopic dermatitis in the future.     

白癜风与CTLA-4基因外显子1 A/G~(49)多态性研究

目的探讨白癜风与细胞毒性T淋巴细胞相关抗原4(CTLA4)基因外显子1第49位点A/G多态性的相关性。方法采用多聚酶链反应限制性片段长度多态性(PCRRFLP)技术分析59例白癜风患者和124例健康对照者CTLA4基因外显子1第49位点的基因型。结果白癜风患者CTLA4基因外显子1第49位点的各基因型分布和等位基因频率与健康对照者相比,无显著性差异(χ2=0.735,P>0.05;χ2=0.684,P>0.05);当患者按有无自身免疫性疾病分类后,伴及不伴有自身免疫性疾病的白癜风患者CTLA4基因外显子1第49位点的各基因型分布及等位基因频率与健康对照者相比较无统计学意义(χ2=2.614,P>0.05;χ2=2.317,P>0.05);当患者按临床型别分类后,各型别等位基因频率与健康对照者相比无统计学意义(χ2=3.076,P>0.05)。结论CTLA4基因外显子1第49位碱基A/G多态性与白癜风的发病可能无相关性;将白癜风患者按有无自身免疫性疾病分类后,发现甚至与白癜风同时伴发的自身免疫性疾病也与CTLA4外显子1第49位点A/G49多态性无关。     

趋化性细胞因子受体CCR4和CXCR3在特应性皮炎患者外周血的表达

目的为研究特应性皮炎患者外周血趋化性细胞因子受体CCR4和CXCR3在特应性皮炎的发病过程中的作用。方法采用三色流式细胞仪测定20例特应性皮炎患者和30例健康对照者外周血趋化性细胞因子受体CCR4和CXCR3的表达水平。结果特应性皮炎患者外周血CCR4+CD4+T细胞的水平明显高于对照组(P<0.01);特应性皮炎患者外周血CCR4/CXCR3比率明显高于对照组P<0.01);特应性皮炎患者外周血CXCR3+CD4+T细胞的水平与对照组差异无统计学意义。结论趋化性细胞因子受体CCR4可能促进了Th2细胞从血液进入特应性皮炎患者炎症皮损。     

Heterogeneity of interleukin 5 genetic background in atopic dermatitis patients: significant difference between those with blood eosinophilia and normal eosinophil levels

BACKGROUND: Blood eosinophil levels in patients with atopic dermatitis vary widely during exacerbation of the disease. We considered that in addition to environmental factors, the genetic background involved with elevating blood eosinophil levels might be heterogeneous among atopic dermatitis patients. OBJECTIVE: We attempted to determine whether a polymorphism of the interleukin (IL)5 gene plays a role in atopic dermatitis, particularly in those patients with blood eosinophilia. Due to the close relation of blood eosinophilia to high IgE productivity, we also assessed these polymorphisms in patients with high IgE concentrations. METHODS: We determined the genotype of the IL5 polymorphism -703C/T in 451 atopic dermatitis patients and 116 normal subjects. The patients were classified into three groups by blood eosinophil levels; less than 7%, from 7 to 15%, and more than 15%, as well as by serum IgE concentrations; less than 500 IU/ml, from 500 to 2000 IU/ml, and more than 2000 IU/ml. RESULTS: IL5 -703C/T was not significantly associated with either total atopic dermatitis patients or individual patients who had both blood eosinophilia and high IgE productivity. However, the distribution of the IL5 -703C/T genotype was significantly different between patients with either blood eosinophilia or high IgE productivity and those without either condition (P=0.0476, P=0.0088, respectively). CONCLUSION: These results suggest that the IL5 gene may play a role in blood eosinophilia associated with atopic dermatitis. We also considered that the IL5 -703C/T gene polymorphism does not have a direct relationship to disease specificity.     

Brain-derived neurotrophic factor gene polymorphisms and serum levels in Chinese atopic dermatitis patients

Background  Brain-derived neurotrophic factor (BDNF) plays an important role in the pathogenesis of atopic dermatitis (AD). Whether BDNF gene polymorphisms are associated with Chinese AD remains totally unknown.
Objective  The aim is to determine if BDNF gene C270T and G196A polymorphisms are associated with Chinese AD, and analyse the clinical relevance of BDNF gene polymorphisms and BDNF serum levels.
Methods  We conducted a case-control association analysis (160 patients and 169 controls) in Northern Chinese subjects. Genotyping was performed by restriction fragment length polymorphism, and serum levels of BDNF were measured using enzyme-linked immunosorbent assay.
Results  For C270T, there were significant differences in C/T genotype distribution ( P  = 0.003) and T allele frequencies ( P  = 0.004) between AD patients and controls in the whole dataset. Higher C/T genotype frequencies were found in male AD (10.6% vs. 1.1%, P  = 0.018) and in intrinsic AD (IAD; 15.79% vs. 2.91%, P  = 0.008). No association between G196A polymorphism and AD was observed in the whole cohort, while A allele was much more frequent in AD patients with atopy in first-degree relatives (65.8% vs. 34.2%, P  = 0.038). Serum BDNF levels were correlated with IAD severity as measured by Scoring Atopic Dermatitis index ( r  = 0.576, P  < 0.001).
Conclusion  T allele in C270T may be a risk factor for AD, especially in IAD and male AD. A allele in G196A may be a risk factor in AD patients with atopy in first-degree relatives. Serum BDNF levels were correlated with the severity of IAD.     

IL-33和IL1RL1基因单核苷酸多态性与特应性皮炎相关性研究

目的：分析IL-33和IL1RL1基因单核苷酸多态性(SNPs)与特应性皮炎（AD）的相关性。方法：PCR-SSP方法检测89例AD患者和138名正常对照组受试者IL-33和IL1RL1编码基因的等位基因和基因型频率。结果：AD患者的IL-33 rs1800925 C等位基因的频率高于对照组，而T等位基因和rs764706552等位基因G低于对照组（均P＜0.001）。IL-33 rs1800925基因型CC和rs764706552基因型CG与AD显著正相关（均P＜0.001）。两组患者的IL1RL1基因的等位基因和基因型频率无明显差异（均P＞0.05）。结论：IL-33基因可能与AD的发病相关。     

儿童特应性皮炎IL-18基因启动子多态性与相关性研究

目的 检测儿童特应性皮炎患者外周血DNA中IL-18基因第2外显子上游启动子1第137和第607位点多态性，探讨其与儿童特应性皮炎发病的相关性。方法 从82例重庆汉族儿童特应性皮炎患者及健康对照组100例的抗凝血中提取DNA，用序列特异性引物PCR扩增技术（PCR-SSP）及PCR产物直接测序法鉴定基因类型，对结果进行统计学分析处理。结果 IL-18基因第2外显子的第137位点核苷酸存在G、C二态性，可表现为GG纯合、CC纯合、GC杂合三种基因型；第607位点核苷酸存在C、A二态性，可表现为CC纯合、AA纯合、CA杂合三种基因型。IL-18-137G/C基因型分布在患者组和对照组间差异有统计学意义，患者组137C等位基因频率显著高于对照组（χ2 = 4.54，P = 0.033），137C等位基因在重度组中分布频率显著高于轻度组（χ2 = 3.93，P < 0.05）；IL-18-607位点等位基因频率在轻度、中度、重度组及对照组之间分布差异无统计学意义（P > 0.05）；IL-18-137G/C位点C等位基因在病例与对照组比较，优势比OR = 1.76，137G/C基因型的优势比OR = 2.33。结论 儿童IL-18基因第2外显子上游启动子1第137和第607位点存在单核苷酸多态性，IL-18-137G/C是特应性皮炎患儿的候选易感基因。     

Skin susceptibility of atopic individuals

The relevance of the irritant skin reaction of individuals with an atopic history (atopic dermatitis, rhinoconjunctivitis or atopic asthma) to sodium lauryl sulfate (SLS), a widely used irritant, is still controversial. The aim of this study was to evaluate transepidermal water loss (TEWL) as an indicator of stratum corneum integrity, before and after SLS patch testing, in various groups of atopic individuals with and without atopic dermatitis. 95 volunteers were divided into 4 groups: (1) individuals with active atopic dermatitis; (2) individuals with a history of atopic dermatitis but without active skin lesions; (3) individuals with rhinoconjunctivitis or atopic asthma without any symptoms at the time of testing; (4) healthy individuals serving as controls. The volunteers were patch-tested at the unaffected volar side of the forearm with aqueous SLS 0.5% for 48 h. TEWL was measured before application and after removal of the patch. Individuals with active atopic dermatitis showed a significantly higher TEWL value after SLS and a tendency to a higher basal TEWL as compared to the 3 other groups. There were no significant differences in TEWL between individuals who were classified as atopic but without active dermatitis, individuals with rhinoconjunctivitis or atopic asthma and healthy controls, either at the basal or at the post-SLS measurement. Enhanced skin susceptibility is only present in individuals with active dermatitis. The skin susceptibility of atopic individuals might therefore be increased as soon as the skin becomes eczematous, suggesting a reduced epidermal integrity probably caused by the endogenous atopy and/or respiratory allergens. When interpreting the atopy score in relation to skin susceptibility, the actual condition of the skin should hence be taken into consideration.     

Interleukin-10 promoter polymorphism in psoriasis.

Beneficial effects of interleukin-10 therapy and lower endogenous interleukin-10 formation compared with atopic dermatitis and cutaneous T cell lymphomas indicated that interleukin-10 is a key cytokine in psoriasis. The interleukin-10 promoter is highly polymorphic, with two informative microsatellites, interleukin-10.G and interleukin-10.R. In order to understand whether interleukin-10 itself is a predisposing gene for the psoriasis susceptibility we analyzed interleukin-10 promotor polymorphism in patients. The distribution of interleukin-10.G and interleukin10.R microsatellite alleles did not vary between patients (n = 78) and healthy controls (n = 80). In addition, when the psoriasis patients were stratified according to age of onset (younger than 40 y of age, or age 40 and older), no difference in allele distribution was observed; however, a clear differential distribution was revealed at the interleukin10.G locus when patients were stratified according to whether they had a positive family history of psoriasis (p = 0.04). This difference was due to an over-representation of the interleukin10.G13 allele in those patients with familial disease (40.4% vs 19.6%, Chi-square = 7.292, p = 0.007). The positive association of allele interleukin10.G13 with familial psoriasis was especially true when patients with an early onset (< 40 y of age) of the disease were compared with those patients with early onset against a nonfamilial background (39.6% vs 14.5%, Chi-square = 8.959, p = 0.003). Patients with age-of-onset of less than 40 were 4-fold [odds ratio = 3.85 (1.55--9.62)] more likely to have a psoriatic family background if they carried this interleukin10.G13 allele. These data suggest that the interleukin-10 locus contributes to the heritability of psoriasis susceptibility.