A study of candidate genes for psoriasis near HLA-C in Chinese patients with psoriasis

Diseases association with the polymorphic major histocompatibility complex class I related chain a: MICA gene

The Major Histocompatibility Complex class I chain-related molecule A (MICA) genes encode a highly polymorphic glycoprotein among the cell surface antigens that trigger an immune response after allograft transplantation. It is encoded by the MICA gene, a member of the glycosylated MIC genes. Discovered in 1994, the MICA gene is located within the MHC class I region. Moreover, its biological function is achieved through the interaction with the NKG2D receptor. Unlike the classical HLA molecules, MICA protein is not associated with β2- microglobulin nor binds peptides. MICA gene expression may result in a cytotoxic response and IFN-γ secretion through the up-regulation by heat shock proteins in response to infection (Human Cytomegalovirus HCMV), mediated by NKG2D-expressing cells. Anti-MICA antibodies were identified as significant risk factors for antibody mediated rejection after being detected in sera of patients with graft rejection. In addition, soluble MICA proteins (sMICA) has been detected in the serum of transplant recipients with cancers. Furthermore, the association of MICA polymorphisms with infectious diseases, various autoimmune diseases, cancer, and allograft rejection or graft-versus-host disease (GVHD) has been studied. Moreover, numerous advanced disease studies centered on MICA polymorphism are independent of HLA association. In this review, we discussed the up-to-date data about MICA and the association of MICA polymorphism with infections, autoimmune diseases, graft-versus-host disease, and cancer.

Time Trends in Psoriasis and Psoriatic Arthritis Incidence from 2002 to 2016 in Taiwan: An Age–Period–Cohort Analysis

Background: Psoriatic disease is a chronic inflammatory disease that is associated with morbidity and a poor quality of life. However, studies on the trends of psoriatic disease incidence are limited. We examined trends in psoriasis and psoriatic arthritis from 2002 to 2016 in Taiwan and distinguished the effects of age, period, and cohort on those trends. Methods: Data from the National Health Insurance Research Database were analyzed for the annual incidence of psoriasis and psoriatic arthritis. An age–period–cohort model was designed in order to investigate the effects of each age, period, and birth cohort on the incidence. Results: From 2002 to 2016, the incidence of psoriasis significantly decreased from 43.33 to 23.14 per 100,000 persons. The incidence of psoriatic arthritis significantly increased from 3.57 to 5.22 per 100,000 persons. In the age–period–cohort analysis, the net age effect on the incidence of psoriasis and psoriatic arthritis increased with advancing age (6-fold and 7.7-fold difference, respectively). Conclusion: The age–period–cohort analysis revealed that the incidence of psoriasis and psoriatic arthritis is associated with older age and early birth cohorts. Elderly individuals in Taiwan may be at a higher risk of developing new-onset psoriasis and psoriatic arthritis.

Gene interaction analysis of psoriasis in Chinese Han population

Background/aims

Psoriasis is a chronic immune‐mediated inflammatory skin disease characterized by excessive proliferation of keratinocytes. It has a strong genetic predisposition; gene‐gene interactions are important genetic models for common diseases. In this study, we explore pair‐wise interactions among SNPs contributing to psoriasis susceptibility.

Methods

We first performed gene interactions with exome‐sequencing, next, we analyzed gene interactions combining the exome sequencing data with the targeted sequencing data. After we sequenced HLA region, we analyzed gene interactions including HLA regions and non‐HLA regions.

Results

We found interactions between HLA regions were significant. We observed significant interactions between HLA‐C*06:02 and rs118179173 (snp31443520; p = 8.21 × 10⁻²⁰, OR = 0.22) and between HLA‐C*06:02 and HLA‐B:AA67 (p = 1.22 × 10⁻¹², OR = 0.45).

Conclusion

This study provides evidence that HLA is the most important susceptibility region on the risk of psoriasis and interactions that occur in this region are still significant.

TNFα gene -238G>A polymorphism is associated with psoriasis patients

BACKGROUND

Tumor Necrosis Factor α (TNFα) is a protein that plays a key role in the pathophysiology of chronic inflammatory disorders like psoriasis.

AIMS

The goal of this study was to see if the TNFα gene -238G>A polymorphism was linked to psoriasis susceptibility.

METHODS

This study comprised ninety psoriasis patients and ninety healthy controls. For the TNFa gene -238G>A polymorphism, genomic DNA was extracted and genotyped using polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) studies.

RESULTS

Psoriasis patients had higher frequencies of the A allele and the AA genotype than the control group, and psoriasis was linked to the AA genotype (OR = 4.25, 95% CI = 1.37-13.1, p = 0.008) and the A allele (OR = 1.55, 95% CI = 1.01-2.34, p = 0.04). Patients with a family history of psoriasis showed an increase in the frequency of the AA genotype compared to GG and GA genotypes (respectively, 46.7%, 36.7%, and 16.7%, p = 0.003). Furthermore, psoriasis patients with the AA genotype were discovered more commonly among those under 30 years old and male patients than those with the GG and GA genotypes, but the differences were not statistically significant.

CONCLUSION

The TNFa gene -238G>A polymorphism has been related to an increased incidence of psoriasis.

HLA-Cw1 and Psoriasis

Psoriasis is a chronic inflammatory skin condition with regional and ethnic differences in its prevalence and clinical manifestations. Human leukocyte antigen (HLA)-Cw6 is the disease allele conferring the greatest risk to psoriasis, but its prevalence is lower in Asian individuals. Recent studies have found associations between HLA-Cw1 and some Asian populations with psoriasis, especially Southern Chinese. HLA-Cw6 was associated with type I early-onset psoriasis, guttate psoriasis, Koebner phenomenon, and better response to methotrexate, interleukin (IL)-12/23, IL-17, and IL-23 targeting drugs. In contrast, HLA-Cw1 positivity has been associated with erythrodermic psoriasis, pustular psoriasis, and the axial type of psoriatic arthritis. Furthermore, HLA-Cw1 was more frequently associated with high-need patients who did not respond to conventional therapies. No known trigger factor nor autoantigen has been identified for HLA-Cw1 positivity. However, HLA-Cw1 has been linked to some viral agents. For example, cytotoxic T lymphocytes recognize multiple cytomegalovirus pp65-derived epitopes presented by HLA alleles, including HLA-C*01:02. In addition, cytomegalovirus can lead to severe exacerbation of psoriatic skin disease. The proposed interaction between viral infection, HLA-Cw1, and psoriasis is through the killer cell immunoglobulin-like receptors of natural killer cells. Given the diverse nature of psoriasis pathogenesis and the difference in HLA-Cw prevalence in different racial groups, more studies are needed to confirm the role of HLA-Cw1 in psoriasis.

Tumor Necrosis Factor-α 308 G/A polymorphism and psoriasis risk: A pooled analysis in different populations

More and more researches have been carried out on the association between the tumor necrosis factor-α (TNF-α) 308 G/A polymorphism and psoriasis, however, controversial results have emerged in these studies. This meta-analysis was performed to quantitatively clarify the relationship between TNF-α 308 G/A polymorphism and the risk of psoriasis in different populations. Databases of PubMed, Springer Link, Ovid, Chinese Wanfang Data Bases, Chinese National Knowledge Infrastructure and Chinese Biology Medicine were investigated until June 2019. The association between the TNF-α 308 G/A polymorphism and psoriasis was evaluated by calculating the pooled odds ratio (OR) and 95% confidence intervals (CIs). A total of 26 studies including 3657 patients and 3197 controls were screened out. In the overall population, the pooled results showed a reduced psoriasis risk with the TNF-α 308 G/A polymorphism (A vs G: OR = 0.77, 95% CI = 0.67-0.89; AA+GA vs GG: OR = 0.72, 95% CI = 0.61-0.86). In the subgroup analysis stratified by geographic locations, the TNF-α 308 G/A polymorphism was significantly associated with a reduced risk of psoriasis in Germany (A vs G: OR = 0.67, 95% CI = 0.57-0.78; AA+GA vs GG: OR = 0.62, 95% CI = 0.52-0.75), as well as in China (AA+GA vs GG: OR = 0.71, 95% CI = 0.52-0.98) and Poland (A vs G: OR = 0.61, 95% CI = 0.38-0.97; AA+GA vs GG: OR = 0.59, 95% CI = 0.35-0.99). This study indicated a significantly reduced psoriasis risk associated with the TNF-α 308 G/A polymorphism in Germans, as well as in Chinese and Poles populations compared with other populations. Ethnicity and geographic locations probably play a pivotal role in the genetic association of psoriasis.

Discovering Genetic Factors for psoriasis through exhaustively searching for significant second order SNP-SNP interactions

In this paper, we aim at discovering genetic factors of psoriasis through searching for statistically significant SNP-SNP interactions exhaustively from two real psoriasis genome-wide association study datasets (phs000019.v1.p1 and phs000982.v1.p1) downloaded from the database of Genotypes and Phenotypes. To deal with the enormous search space, our search algorithm is accelerated with eight biological plausible interaction patterns and a pre-computed look-up table. After our search, we have discovered several SNPs having a stronger association to psoriasis when they are in combination with another SNP and these combinations may be non-linear interactions. Among the top 20 SNP-SNP interactions being found in terms of pairwise p-value and improvement metric value, we have discovered 27 novel potential psoriasis-associated SNPs where most of them are reported to be eQTLs of a number of known psoriasis-associated genes. On the other hand, we have inferred a gene network after selecting the top 10000 SNP-SNP interactions in terms of improvement metric value and we have discovered a novel long distance interaction between XXbac-BPG154L12.4 and RNU6-283P which is not a long distance haplotype and may be a new discovery. Finally, our experiments with the synthetic datasets have shown that our pre-computed look-up table technique can significantly speed up the search process.

Psoriasis in Skin of Color: Insights into the Epidemiology, Clinical Presentation, Genetics, Quality-of-Life Impact, and Treatment of Psoriasis in Non-White Racial/Ethnic Groups

Psoriasis is a chronic inflammatory skin condition affecting diverse racial/ethnic groups throughout the world. Large population-based studies suggest that psoriasis occurs most often in individuals of European ancestry, followed by black and Hispanic individuals, although the true prevalence of psoriasis in non-white individuals is likely underestimated. Despite similarities in psoriasis between ethnic groups, there are notable differences in the presentation, quality-of-life impact, and treatment of psoriasis with important implications for the management of non-white individuals. Overall, heterogeneity in psoriasis susceptibility alleles, in combination with cultural and socioeconomic factors, may explain these differences. In this article, we review the epidemiology, clinical presentation, genetic polymorphisms, quality-of-life impact, and treatment nuances of psoriasis in patients with skin of color.

HLA-Cw6 and psoriasis

Psoriasis is a multifactorial disease with a strong genetic background. HLA-Cw6 is one of the most strongly associated psoriasis susceptibility alleles. It is repeatedly observed to affect disease course, phenotypic features, severity, comorbidities and treatment outcomes. To the best of our knowledge, the roles of HLA-Cw6 in psoriasis have not yet been thoroughly reviewed. The worldwide frequency of the HLA-Cw6 allele varies greatly, with it being generally higher in white people than in Asians. The allele is associated with type I early-onset psoriasis. Stress, obesity and streptococcal pharyngitis are commonly observed in HLA-Cw6-positive patients. Phenotypically, HLA-Cw6 has been found to be associated with guttate psoriasis. In addition, patients carrying the allele are more likely to have arm, leg and trunk involvement, and the Koebner phenomenon. Patients with psoriatic arthritis with HLA-Cw6 more often have early onset and tend to show cutaneous symptoms before musculoskeletal symptoms. HLA-Cw6-positive patients have been shown in several studies to be more responsive to methotrexate and ustekinumab. However, this difference in ustekinumab efficacy was only moderate in a post-hoc analysis of a pivotal phase III study. HLA-Cw6 positivity also tends to be less frequent in high-need patients who fail conventional therapy. Small studies have also investigated the role of HLA-Cw6 in remission of psoriasis during pregnancy, and with the comorbidities of photosensitivity and atherosclerosis. Given the diverse nature of psoriasis pathogenesis, as well as the difference of HLA-Cw6 positivity in different ethnic groups, more studies are needed to confirm the role of HLA-Cw6 in psoriasis.

The HLA-C*06 allele as a possible genetic predisposing factor to psoriasis in South Indian Tamils

Psoriasis is a multi-factorial heritable prototypical immune-mediated inflammatory disease, characterized by hyperproliferation of keratinocytes in the affected skin. There are no studies till date, to the best of our knowledge, about the association of HLA-C*06, the risk variant in the PSORS 1 susceptibility locus that confers the greatest risk for early onset of psoriasis, with the disease in South Indian Tamil patients with psoriasis. The present study was performed to determine the association of HLA-C*06 with psoriasis in the South Indian Tamil ethnic population. Three hundred and fifty-five cases of psoriasis and 360 healthy controls were included in this case-control study. Severity grading according to psoriasis area severity index (PASI) scoring was done in patients with psoriasis. PCR assays with sequence-specific primers (PCR-SSP) were used for specific detection of HLA-C*06. PCR with analysis of restriction fragment length polymorphism was used to distinguish between patients homozygous and heterozygous for HLA-C*06. We observed that those with the HLA-C*06-positive allele had a 3.5 times higher odds of having psoriasis compared to those without, [p < 0.0001, OR 3.5, 95 % CI (2.59-4.79)]. Among cases of psoriasis, it was noted that there was a significant association of HLA-C*06 positivity with female psoriatics [p = 0.006; OR 2.49 (1.28-4.87)] and early age of onset of psoriasis [p = 0.002; OR 2.04 (1.29-3.20)]. Our results suggest that the HLA-C*06 allele is positively associated with susceptibility to psoriasis, female gender and early onset of psoriasis in South Indian Tamils.

Associations of MICA Polymorphisms with Inflammatory Rheumatic Diseases

Inflammatory rheumatic diseases are characterized by inflammation resulting from the immune dysregulation that usually attacks joints, skin and internal organs. Many of them are considered as complex disease that may be predisposed by multiple genes and/or genetic loci, and triggered by environmental factors such as microbiome and cellular stress. The major histocompatibility complex class I chain-related gene A (MICA) is a highly polymorphic gene that encodes protein variants expressed under cellular stress conditions, and these MICA variants play important roles in immune activation and surveillance. Recently, accumulating evidences from both genetic and functional studies have suggested that MICA polymorphisms may be associated with various rheumatic diseases, and the expression of MICA variants may attribute to the altered immune responses in the diseases. The objective of this review is to discuss potential genetic associations and pathological relevance of MICA in inflammatory rheumatic diseases that may help us to understand pathogenesis contributing to the development of these diseases.

HLA-C and TNF gene polymorphisms are associated with psoriasis in Brazilian patients

BACKGROUND

Polymorphisms at the human leukocyte antigens (HLA-C) and tumor necrosis factor (TNF) genes have been associated with susceptibility to psoriasis in several worldwide populations. In this study, HLA-C and TNF (-238/-308) polymorphisms were performed in 125 Brazilian patients and 202 healthy controls.

METHODS

HLA-C and TNF promoter region alleles were typed by polymerase chain reaction using sequence-specific primer-polymerase chain reaction.

RESULTS

The presence of HLA-C*06 was associated with psoriasis onset, particularly in younger patients, being more frequent for patients with disease onset before the age of 20 years (P = 0.03), 25 years (P = 0.01), or 30 years (P = 0.03). No association between HLA-C*06 and psoriasis was observed for patients older than 35 years. Susceptibility to psoriatic arthritis was associated with the TNF -238 G/A genotype (P = 0.02). The TNF -308A allele was overrepresented in patients (P = 0.0061), and the TNF -308 G/A genotype was increased in generalized forms (erythrodermic and generalized pustular psoriasis) compared to plaque psoriasis (P < 0.001). The TNF -238A/HLA-C*06 haplotype was overrepresented in patients (P = 0.025), while the TNF -238G/HLA-C*15 haplotype was increased in controls (P = 0.037).

CONCLUSIONS

The strong association of HLA-C*06 allele with disease susceptibility, particularly in early onset psoriasis, indicates that younger ages could be considered to stratify psoriasis into early and late types. TNF -308 polymorphisms can be associated with psoriasis susceptibility and severity. Potential genetic markers of psoriasis in populations with a complex mixture of ethnicities should be investigated.

Desmosomes: regulators of cellular signaling and adhesion in epidermal health and disease

Desmosomes are intercellular junctions that mediate cell-cell adhesion and anchor the intermediate filament network to the plasma membrane, providing mechanical resilience to tissues such as the epidermis and heart. In addition to their critical roles in adhesion, desmosomal proteins are emerging as mediators of cell signaling important for proper cell and tissue functions. In this review we highlight what is known about desmosomal proteins regulating adhesion and signaling in healthy skin-in morphogenesis, differentiation and homeostasis, wound healing, and protection against environmental damage. We also discuss how human diseases that target desmosome molecules directly or interfere indirectly with these mechanical and signaling functions to contribute to pathogenesis.

Human leucocyte antigen-Cw6 as a predictor for clinical response to ustekinumab, an interleukin-12/23 blocker, in Chinese patients with psoriasis: a retrospective analysis

BACKGROUND

Ustekinumab, an interleukin-12/23 inhibitor, is effective in the treatment of psoriasis. A recent Italian study showed more favourable response to ustekinumab in patients with positive human leucocyte antigen (HLA)-Cw6. Nonetheless, there are differences in genetic susceptibility to psoriasis between races, and no studies have specifically assessed the candidate genetic markers in predicting therapy outcome in Chinese patients with psoriasis treated with ustekinumab.

OBJECTIVES

To determine whether HLA gene polymorphisms can predict the response to ustekinumab in Chinese patients with psoriasis.

METHODS

Sixty-six patients with psoriasis treated with ustekinumab were included in the study, and the effectiveness of ustekinumab therapy was evaluated at weeks 0, 16 and 28 by Psoriasis Area and Severity Index (PASI).

RESULTS

More HLA-Cw6-positive patients achieved a PASI 75 response at week 4 compared with HLA-Cw6-negative patients (38% vs. 9%, P = 0·019). Similarly, at week 16, patients carrying the HLA-Cw6 allele showed a higher likelihood of achieving PASI 50, 75 and 90 than Cw6-negative patients, although this was not statistically significant. At week 28, a significantly higher percentage of HLA-Cw6-positive patients maintained PASI 90 response compared with Cw6-negative patients (63% vs. 26%, P = 0·035). Further analysis of other HLA allele polymorphisms did not show significant associations with therapeutic response to ustekinumab.

CONCLUSIONS

This pharmacogenetic study provides preliminary data indicating that positive HLA-Cw6 is associated with a good response to ustekinumab treatment in Chinese patients with psoriasis.

Single nucleotide polymorphisms in the tumor necrosis factor-alpha gene promoter region alter the risk of psoriasis vulgaris and psoriatic arthritis: a meta-analysis

BACKGROUND

It has been confirmed that tumor necrosis factor-alpha (TNFα), a macrophage-derived pro-inflammatory cytokine, plays an important role in the pathogenesis of psoriasis vulgaris and psoriatic arthritis (PsV&PsA). In contrast, the reported association of TNFα gene promoter region single nucleotide polymorphisms (SNPs) and PsV&PsA has remained controversial. Accordingly, we performed a meta-analysis to provide new evidence that SNPs in the TNFα gene promoter region alter not only the risk of psoriasis vulgaris (PsV) or psoriatic arthritis (PsA) but also of PsV&PsA.

METHODS

Interrelated literature dated to October 2012 was acquired from the PubMed, ScienceDirect, and SpringerLink databases. The number of the genotypes and/or alleles for the TNFα promoter in the PsV and PsA and control subjects was obtained. Odds ratios (ORs) and 95% confidence intervals (CIs) were used to calculate the risk of PsV and/or PsA with TNFα promoter SNPs.

RESULTS

A total of 26 papers of 2159 for PsV (2129 normal controls) and 2360 for PsA (2997 normal controls) were included in our meta-analysis. The results showed that the variant genotype and allele of TNFα -308A/G was protective in pooled groups of patients with PsV&PsA (OR = 0.682, 0.750; 95% CI, 0.596-0.779, 0.653-0.861). However, the variant genotypes and alleles of TNFα -238A/G and -857T/C had an increased risk of PsV&PsA (OR = 2.493, 2.228, 1.536, 1.486, 95% CI, 1.777-3.498, 1.628-3.049, 1.336-1.767, 1.309-1.685). Moreover, the meta-analysis revealed a significant association between TNFα -238A/G and -857T/C polymorphism and PsA susceptibility (OR = 2.242, 2.052, 1.419, 1.465; 95% CI, 1.710-2.941, 1.614-2.610, 1.214-1.658, 1.277-1.681). In contrast, the variant genotypes and alleles of TNFα -308A/G proved to be protective against PsV (OR = 0.574, 0.650, 95% CI, 0.478-0.690, 0.556-0.759), whereas TNFα -238A/G was found to have a risk association (OR = 2.636, 2.223, 95% CI, 1.523-4.561, 1.317-3.751).

CONCLUSIONS

SNPs in the TNFα gene promoter region alter the risk of PsV and/or PsA.

Etanercept use for psoriasis in Taiwan: a case series study

BACKGROUND

The reported efficacy and safety of some biologic agents for psoriasis vary between Caucasians and Asians. Few reports of etanercept exist in psoriasis patients within the Asia-Pacific region.

OBJECTIVES

The study aims to report our clinical experience of etanercept in the treatment of patients with moderate-to-severe psoriasis in Taiwan.

METHODS

A retrospective analysis of 59 patients with moderate-to-severe psoriasis who received etanercept was conducted in a tertiary referral center.

RESULTS

Etanercept therapy resulted in a reduction of mean Psoriasis Area and Severity Index (PASI) of 47% at week 12 and 61% at week 24. After 12 weeks of treatment, 48%, 26%, and 3.4% of the patients achieved at least PASI50, 75 and 90 response, respectively. At week 24, the proportion of patients achieving at least PASI50, 75 and 90 response was 59%, 37%, and 14%, respectively. Etanercept efficacy in achieving PASI75 improvement was, however, lower than that reported in previous pivotal placebo-controlled trials. No cases of active tuberculosis, viral hepatitis or malignancies were observed during the observation period.

CONCLUSION

Our case series demonstrated the efficacy and safety of etanercept for the management of moderate-to-severe psoriasis in Taiwan.

Comorbidity profiles among patients with alopecia areata: the importance of onset age, a nationwide population-based study

BACKGROUND

Alopecia areata (AA) is considered an autoimmune disease with undetermined pathogenesis. Age at onset predicts distinct outcomes. A nationwide study of the relationship of AA with associated diseases stratified by onset age has rarely been reported.

OBJECTIVE

We sought to clarify the role of atopic and autoimmune diseases in AA, thereby better understanding its pathogenesis.

METHODS

A total of 4334 patients with AA were identified from the National Health Insurance Database in Taiwan from 1996 to 2008. A national representative cohort of 784,158 persons served as control subjects.

RESULTS

Among patients with AA, there were significant associations with vitiligo, lupus erythematosus, psoriasis, atopic dermatitis, autoimmune thyroid disease, and allergic rhinitis. Different ages at onset resulted in disparate comorbidities. Increased risk of atopic dermatitis (odds ratio [OR] 3.82, 95% confidence interval 2.67-5.45) and lupus erythematosus (OR 9.76, 95% confidence interval 3.05-31.21) were found in childhood AA younger than 10 years. Additional diseases including psoriasis (OR 2.43) and rheumatoid arthritis (OR 2.57) appeared at onset age 11 to 20 years. Most atopic and autoimmune diseases were observed at onset ages of 21 to 60 years. With onset age older than 60 years, thyroid disease (OR 2.52) was highly related to AA. Moreover, patients with AA had higher risk for more coexisting diseases than control subjects.

LIMITATIONS

We could not differentiate hypothyroidism from hyperthyroidism.

CONCLUSIONS

AA is related to various atopic and autoimmune diseases. Different associated diseases in each onset age group of AA can allow clinician to efficiently investigate specific comorbidities.

Simple and rapid screening for HLA-Cw*06 in Polish patients with psoriasis

BACKGROUND

The human leucocyte antigen (HLA) C allele Cw*06 is currently recognized as a major disease allele at the PSORS1 locus. It has been suggested that characterization of this gene could be used as a convenient criterion for classification of psoriasis phenotypes.

AIM

To design and optimize a DNA typing procedure, suitable for identification of HLA-Cw*06 and its zygosity status verification in large-scale analyses, and to test for its robustness in a case-control study.

METHODS

PCR assays with sequence-specific primers (PCR-SSP) were used for specific detection of HLA-Cw*06. PCR with analysis of restriction fragment length polymorphism was used to distinguish between patients homozygous and heterozygous for HLA-Cw*06. Additionally, those homozygous for HLA-Cw*06 were screened for nonspecific digestion by degenerated PCR-SSP. This three-step procedure was used in the examination of 383 patients with psoriasis that developed at the age of >or= 30 years of age and of 143 healthy subjects from northern Poland.

RESULTS

A simple and rapid procedure for screening of HLA-Cw*06 was produced. A significant difference in HLA-Cw*06 frequency between patients with psoriasis and controls was seen (P = 0.02). Detailed examination of the age of disease onset among patients with psoriasis revealed that involvement of HLA-Cw*06 in the genetic background of psoriasis developing as late as the age of 45 years cannot be neglected.

CONCLUSIONS

The low cost, high-throughput capacity and requirement for small sample amounts make this procedure a useful one for HLA-Cw*06 typing in clinical practice and large population studies. We recommend that patients with psoriasis diagnosed before 45 years of age should be considered for diagnostic HLA-Cw*06 typing.

TNF-α Gene Promoter -238G>A and -308G>A Polymorphisms Alter Risk of Psoriasis Vulgaris: A Meta-Analysis

Tumor necrosis factor-alpha (TNF-alpha) is a major proinflammatory cytokine and involved in the etiology of psoriasis. The -238G>A and -308G>A polymorphisms influence the transcription of the TNF-alpha gene and have been implicated in psoriasis risk. However, the results from the published studies on the association between TNF-alpha polymorphisms and psoriasis risk are conflicting. Our meta-analysis of a total of 997 psoriasis cases and 943 control subjects from eight published case-control studies for the -238G>A polymorphism and of 1,156 psoriasis cases and 1,083 control subjects from 10 published case-control studies for the -308G>A polymorphism showed that a significantly increased risk was associated with the variant GA+AA genotypes of -238G>A, compared with the GG genotype (odds ratio (OR) 2.60, 95% confidence interval (95% CI) 1.48-4.56), whereas a significantly reduced psoriasis risk was associated with the variant GA+AA genotypes of the -308G>A compared with the GG genotype (OR 0.57, 95% CI 0.45-0.71). Our findings suggest that TNF-alpha -238G>A and -308G>A polymorphisms might be used as biomarkers for psoriasis risk prediction. A single larger study with thousands of subjects and biochemical and biological characterization is warranted to evaluate further the role of -238G>A and -308G>A polymorphisms and psoriasis risk in a population of various ethnicities.

Spectrum of skin disorders in human immunodeficiency virus-infected patients in Singapore and the relationship to CD4 lymphocyte counts

BACKGROUND

Skin disorders are extremely common and cause significant morbidity in human immunodeficiency virus (HIV)-infected individuals. There are few data on their prevalence and association with CD4 counts in Asians.

AIM

To evaluate the prevalence of skin disorders in ambulatory HIV-infected individuals attending a specialized skin clinic in Singapore and the association with the degree of immunosuppression.

METHODS

A cross-sectional study on skin disorders in HIV-positive outpatients in the Communicable Disease Centre of Singapore was performed. The association between skin disease prevalence and CD4 count was evaluated using logistic regression.

RESULTS

Ninety-six patients (male : female, 8 : 1) were enrolled. The most common mode of HIV transmission was heterosexual (75%), followed by homosexual/bisexual contacts (22%), and intravenous drug abuse (3%). The distribution of patients in terms of current CD4 cell counts was as follows: 38.5% with less than 50 x 10(6)/L, 25% with between 50 and 199/microL, and 36.5% with at least 200 x 10(6)/L. The most common skin disorder was pruritic papular eruption (PPE) of HIV infection (31 cases), followed by psoriasis (24), seborrheic dermatitis (18), xerosis (17), herpes simplex (17), and adverse drug eruptions (17). A CD4 cell count of less than 200 x 10(6)/L was significantly associated with a higher number of skin disorders (P = 0.002) and the development of psoriasis [odds ratio (OR), 8.97; 95% confidence interval (CI), 1.70-47.16; P = 0.010], PPE (OR, 3.40; 95% CI, 1.21-9.53; P = 0.020), and adverse drug eruption (OR, 5.83; 95% CI, 1.21-28.00; P = 0.028).

CONCLUSIONS

A preponderance of inflammatory dermatoses and an absence of skin tumors characterized this study. A low CD4 cell count was associated with a higher number of skin disorders and an increased incidence of PPE, psoriasis, and adverse drug eruptions.

Cytokine gene polymorphisms in Chinese patients with psoriasis

BACKGROUND

Previous studies have shown that cytokine gene polymorphisms may confer susceptibility to psoriasis.

OBJECTIVES

To determine whether genetic polymorphisms of the cytokine genes might influence the development of psoriasis in Chinese patients in Taiwan.

METHODS

DNA samples were obtained from 170 patients with psoriasis vulgaris (PV), 102 patients with psoriatic arthritis (PsA) and 210 control subjects. Using direct sequencing and microsatellite genotyping, we examined 28 polymorphisms in 11 cytokine genes including the interleukin (IL)-1alpha, IL-1beta, IL-1 receptor antagonist, IL-4, IL-8, IL-10, IL-12B, IL-13, tumour necrosis factor (TNF)-alpha, TNF-beta and interferon-gamma genes. Genotypes of HLA-Cw*0602, killer cell immunoglobulin-like receptor (KIR) genes and major histocompatibility complex class I chain-related gene A (MICA) were also determined in patients with PsA.

RESULTS

The patients with PV were more likely to carry the +4496G allele of the IL-12B gene (59.4% vs. 49.3%, P = 0.0067, P(c) = 0.033). However, no significantly different allelic and genotypic distributions of the other analysed genes including IL-1beta, TNF-alpha, TNF-beta, KIR genes and MICA were found between the PV/PsA patients and controls. Moreover, no association was observed with disease onset, gender, peripheral arthritis or joint erosion. With regards to HLA-Cw*0602, its allele frequency was significantly increased in patients with early-onset PV (25.3% vs. 4.8%, P < 10(-7)), but not in patients with PsA.

CONCLUSIONS

The IL-12B gene polymorphism conferred a risk for PV in our Chinese population, although the effect was more minor than that of HLA-Cw*0602. Cw*0602, KIR2DS1/S2 and MICA-A9 were unlikely to be risk alleles in our patients with PsA. The other analysed genetic polymorphisms of cytokine genes do not appear to be associated with susceptibility to PV and PsA in Chinese patients in Taiwan.

Psoriasis vulgaris in Chinese individuals is associated withPSORS1C3andCDSNgenes

BACKGROUND

Besides the HLA-Cw*0602 allele, the psoriasis susceptibility 1 candidate 3 (PSORS1C3) and corneodesmosin (CDSN) genes are two probable psoriasis susceptibility genes in the PSORS1 locus. The -79C, -26C and +246A alleles of the PSORS1C3 gene, the CDSN*971T allele, CDSN*TTC (619T-1236T-1243C) and CDSN*5 (619T-1240G-1243C) are strongly associated with psoriasis in the caucasian population. Until now, no haplotype study of the PSORS1C3 and CDSN genes has been documented in Chinese patients with psoriasis vulgaris.

OBJECTIVES

We aimed to determine whether genetic polymorphisms of the PSORS1C3 and CDSN genes were associated with an increased risk of psoriasis vulgaris in Chinese patients in Taiwan.

METHODS

We investigated the PSORS1C3 and CDSN genes for disease association by direct sequencing in 178 patients with psoriasis vulgaris and 203 control subjects. Genotyping for HLA-Cw*0602, alpha-helix coiled-coil rod homologue (HCR) gene and single nucleotide polymorphism (SNP) n.9 was also carried out using a sequence-based typing method.

RESULTS

The PSORS1C3*582A allele, an SNP in the 3'-untranslated region of the PSORS1C3 gene, was a major psoriasis vulgaris susceptibility allele in the Chinese population, and the association was much stronger in patients with early-onset psoriasis vulgaris (22.3% vs. 6.9%, odds ratio = 3.87, P(c) =0.0000072). The frequencies of CDSN*TTC and CDSN*971T were also significantly increased in patients with early-onset psoriasis vulgaris. Moreover, PSORS1C3*582A, SNP n.9*C, Cw*0602 and HCR*WWCC were in near complete linkage disequilibrium (LD) with each other; in contrast, the LD with the CDSN gene was not so strong. SNP n.9*C-Cw*0602-PSORS1C3*582A-HCR*WWCC was a major susceptibility haplotype in patients with early-onset psoriasis vulgaris (P < 10(-7)) and this risk haplotype also carried CDSN*TTC and CDSN*971T.

CONCLUSIONS

The PSORS1C3 and CDSN genes are important psoriasis susceptibility genes in Chinese patients with psoriasis vulgaris.

Sequence and haplotype analysis supports HLA-C as the psoriasis susceptibility 1 gene

Previous studies have narrowed the interval containing PSORS1, the psoriasis-susceptibility locus in the major histocompatibility complex (MHC), to an approximately 300-kb region containing HLA-C and at least 10 other genes. In an effort to identify the PSORS1 gene, we cloned and completely sequenced this region from both chromosomes of five individuals. Two of the sequenced haplotypes were associated with psoriasis (risk), and the other eight were clearly unassociated (nonrisk). Comparison of sequence of the two risk haplotypes identified a 298-kb region of homology, extending from just telomeric of HLA-B to the HCG22 gene, which was flanked by clearly nonhomologous regions. Similar haplotypes cloned from unrelated individuals had nearly identical sequence. Combinatorial analysis of exonic variations in the known genes of the candidate interval revealed that HCG27, PSORS1C3, OTF3, TCF19, HCR, STG, and HCG22 bore no alleles unique to risk haplotypes among the 10 sequenced haplotypes. SPR1 and SEEK1 both had messenger RNA alleles specific to risk haplotypes, but only HLA-C and CDSN yielded protein alleles unique to risk. The risk alleles of HLA-C and CDSN (HLA-Cw6 and CDSN*TTC) were genotyped in 678 families with early-onset psoriasis; 620 of these families were also typed for 34 microsatellite markers spanning the PSORS1 interval. Recombinant haplotypes retaining HLA-Cw6 but lacking CDSN*TTC were significantly associated with psoriasis, whereas recombinants retaining CDSN*TTC but lacking HLA-Cw6 were not associated, despite good statistical power. By grouping recombinants with similar breakpoints, the most telomeric quarter of the 298-kb candidate interval could be excluded with high confidence. These results strongly suggest that HLA-Cw6 is the PSORS1 risk allele that confers susceptibility to early-onset psoriasis.

Psoriasis in Norway as observed in a population-based Norwegian twin panel

BACKGROUND

Psoriasis is a chronic T-cell-mediated immunological skin disease. The occurrence of the disease appears to differ with geography and ethnicity. There is a need for epidemiological data obtained from defined population-based studies, and the sex-specific differences observed in the natural history of the disease require more attention.

OBJECTIVES

To describe the occurrence and risk of psoriasis in Norway by age and sex.

PATIENTS/METHODS

A population-based health survey was conducted in 1998 in Norwegian twins aged 19-31 years. The present study is based upon the self-reported history of psoriasis among the 8045 questionnaire responders.

RESULTS

Altogether, 334 (4.2%) reported a positive history of psoriasis. There were no sex differences in the overall prevalence rates, but significantly higher point-prevalences emerged in females in the teenage-year intervals. A fairly linear increase in incidence rates by every 4-year age-interval peaked at a lower age in females. The mean age at onset was also significantly lower in females (14.8 years) than in males (17.3 years). The absolute risk of developing psoriasis appeared higher for females across the entire age range. However, by the age of 31 the cumulative risks were similar in females and males (0.056 and 0.053, respectively).

CONCLUSIONS

In this historical cohort of Norwegian twins, we find a high prevalence of psoriasis in congruence with previously reported data among whites in north-western Europe. We have found sex-specific characteristics in point-prevalences and incidence rates which may contribute to the understanding of the earlier age at onset of the disease in females.

A study of PSORS1C1 gene polymorphisms in Chinese patients with psoriasis

BACKGROUND

Although genetic analyses have identified the HLA-Cw*0602 allele as the major risk allele for chronic plaque psoriasis in various ethnic groups, it has been proposed that the association of Cw*0602 is due to linkage disequilibrium and that other nearby genes are involved in susceptibility to psoriasis. The psoriasis susceptibility 1 candidate 1 (PSORS1C1, formerly SEEK1) gene, located 127 kb telomeric to the HLA-C locus, is considered to be one of the potential candidate genes of psoriasis. Up to the present, no association study of the PSORS1C1 gene has been conducted on Chinese patients with psoriasis.

OBJECTIVES

We aimed to determine whether the genetic polymorphisms of the PSORS1C1 gene were associated with an increased risk of psoriasis in Chinese patients.

METHODS

We investigated the PSORS1C1 gene for disease association by direct sequencing of the PSORS1C1 gene in 143 Chinese patients with chronic plaque psoriasis and 188 control subjects. Genotyping for HLA-Cw*0602 and the alpha-helix coiled-coil rod homologue (C6orf18, formerly HCR) gene was also carried out using a sequence-based typing method.

RESULTS

We identified 10 single nucleotide polymorphisms (SNPs) on the PSORS1C1 gene in our subjects; four of these SNPs cause amino acid change. We also detected poly(C) repeat variants from nucleotide positions 386-392 (poly(C)6-8). The poly(C) repeat polymorphisms cause a frame shift mutation. Another poly(C) repeat variant was also found at nucleotide positions 748-751. No significantly different allelic distributions of the PSORS1C1 SNPs or poly(C) repeat polymorphisms could be found between the patients with chronic plaque psoriasis and controls after correction for multiple testing. However, a significant increase of the Cw*0602 allele and tryptophan-tryptophan allele of the C6orf18 gene (HCR*WW) was found in patients with early onset psoriasis (21.9% vs. 4.8%, P < 10(-7)). Haplotype-based association analysis also showed a susceptibility haplotype carrying Cw*0602 and HCR*WW alleles in early onset Chinese patients.

CONCLUSIONS

Our results indicate that the PSORS1C1 gene might not play an important role in the causation of chronic plaque psoriasis in Chinese people.

Fine mapping of the psoriasis susceptibility gene PSORS1: a reassessment of risk associated with a putative risk haplotype lacking HLA-Cw6

Human leukocyte antigen (HLA)-Cw6 has long been associated with psoriasis, and PSORS1 (psoriasis susceptibility 1), a major gene for psoriasis susceptibility, has been mapped to its vicinity. A previous analysis identified multiple risk haplotypes carrying HLA-Cw6 and one haplotype (cluster 17, HLA-Cw8-B65) that appeared to carry risk for psoriasis but did not carry HLA-Cw6. This haplotype was very similar to other risk haplotypes for at least 60 kb telomeric to HLA-C, suggesting identity by descent with the remaining risk chromosomes. The association, however, between psoriasis and this haplotype as assessed by the transmission/disequilibrium test (TDT) was of borderline significance (p-value 0.048). In order to better assess the risk associated with cluster 17, a multicenter collaboration typed additional subjects for a single marker (M6S161) for which one allele (249 bp) was found only on cluster 17. The new sample included 1275 pedigrees as well as 300 cases and 913 controls. Transmission of this allele to affected individuals was examined using the TDT and the pedigree disequilibrium test (PDT), and case-control samples were analyzed by a trend test across genotype categories. By all methods, the newly acquired genotypes failed to confirm the association originally reported, despite adequate power. In contrast, the 248 bp allele, which is found on all HLA-Cw6-positive risk haplotypes as well as several non-risk haplotypes, shows significant excess transmission for all cohorts. Taken together, these results indicate that cluster 17 does not carry a psoriasis-susceptibility allele, and expand the PSORS1 risk interval to approximately 300 kb.

Mapping of the major psoriasis-susceptibility locus (PSORS1) in a 70-Kb interval around the corneodesmosin gene (CDSN)

Numerous putative susceptibility loci have been described for psoriasis. Among the loci confirmed in the literature, PSORS1 (the major histocompatibility complex at 6p21.3) has the strongest effect. Recent studies have highlighted a 200-kb candidate region. However, this region has not been well delimited, mainly because of the strong linkage equilibrium among the associated alleles. To finely map PSORS1, we set up a study using 17 polymorphic markers in a 525-kb interval around the human leucocyte antigen C locus (HLA-C). The results uncovered five loci with alleles strongly associated with psoriasis (Sidak-corrected P [P(c)] values from 1.8 x 10(-7) to .003), all structured in a psoriasis-susceptibility haplotype (PSH). Subsequent analysis of extended haplotypes showed that the PSH was not only present on the traditional psoriasis-susceptibility extended haplotypes (HLA-Cw6-B57, HLA-Cw6-B37, and HLA-Cw6-B13) but also on a haplotype of Sardinian origin (HLA-Cw7-B58) found to be associated with psoriasis (Pc=.0009) because of an ancestral recombination with one of the susceptibility haplotypes carrying the HLA-Cw6 allele. Comparisons of the regions identical by descent among associated and nonassociated haplotypes highlighted a minimum region of 70 kb not recombinant with PSORS1, around the corneodesmosin (CDSN) gene.

An update on the genetics of psoriasis

Psoriasis is a complex inflammatory disorder whose pathogenesis is likely to require the contribution of several genes and environmental triggers. Despite the difficulties posed by the study of multifactorial conditions, significant progress has been achieved in relation to the molecular genetic basis of psoriasis. It has long been recognized that the major histocompatibility complex (MHC) region on chromosome 6p21 harbors the main determinant conferring psoriasis susceptibility. The identification of non-MHC susceptibility regions across the genome has been hindered by the likely occurrence of genetic heterogeneity. Nonetheless, evidence for the assignment of a number of non-MHC loci has been achieved through studies, including the collaborative analysis of large patient cohorts, and also through the observation of overlap between psoriasis and atopic dermatitis susceptibility regions.

Genetic polymorphisms of the HCR gene and a genomic segment in close proximity to HLA-C are associated with patients with psoriasis in Taiwan

BACKGROUND

Although psoriasis vulgaris (PV) is strongly associated with HLA-Cw*0602, it has been proposed that the association of Cw*0602 is due to linkage disequilibrium and that other nearby genes are involved in PV susceptibility. The alpha-helix coiled-coil rod homologue (HCR) gene, located 110 kb telomeric to the HLA-C locus, is presumed to be one of the PV candidate genes. Recently, a 10-kb genomic segment, centromeric to HLA-C, defined by two new single nucleotide polymorphisms (SNPs) n.7*A and n.9*C, was found to have a stronger association with psoriasis than the HCR gene. Until now, no study of the association of the HCR gene, SNPs n.7, and n.9 has been conducted on Chinese patients with psoriasis.

OBJECTIVES

We aimed to determine whether the genetic polymorphisms of the HCR gene, SNPs n.7*A, and n.9*C were associated with an increased risk of psoriasis in Chinese patients.

METHODS

Using direct sequencing of the HCR gene and the genomic region containing SNPs n.7 and n.9, we investigated the HCR gene, SNPs n.7, and n.9 for disease association in 115 Chinese patients with psoriasis and 103 control subjects. The HCR SNPs were confirmed by denaturing high performance liquid chromatography. Genotyping for HLA-Cw*0602 was also carried out using sequence-based typing.

RESULTS

We observed a different allelic distribution between patient and control groups at nucleotide positions 386, 404, 1802 and 2406 of the HCR gene, and SNPs n.7, and n.9. The associations were much stronger in early onset PV patients (for HCR-386*T and HCR-404*T, odds ratio = 5.63, Pc < 0.0001). The HLA-Cw*0602 also displayed a similar association with PV (odds ratio = 5.4, Pc < 0.0001). Moreover, SNP n.7*A, SNP n.9*C, Cw*0602, HCR-386*T, HCR-404*T and HCR-1802*T were in linkage disequilibrium with each other. Haplotype-based association analysis showed SNP n.7*A-SNP n.9*C-Cw*0602-HCR-386*T-HCR-404*T-HCR-1802*T-HCR-2406*G as a major susceptibility haplotype in this Chinese population (for early onset patients, odds ratio = 5.15, Pc < 0.0001).

CONCLUSIONS

Our results indicate that the HCR gene, SNP n.7*A, and SNP n.9*C as well as Cw*0602 are major susceptibility markers for psoriasis in Chinese patients.