Psoriasis is a common inflammatory skin disease with complex genetics and different degrees of prevalence across ethnic populations. Here we present the largest trans-ethnic genome-wide meta-analysis (GWMA) of psoriasis in 15,369 cases and 19,517 controls of Caucasian and Chinese ancestries. We identify four novel associations at LOC144817, COG6, RUNX1 and TP63, as well as three novel secondary associations within IFIH1 and IL12B. Fine-mapping analysis of MHC region demonstrates an important role for all three HLA class I genes and a complex and heterogeneous pattern of HLA associations between Caucasian and Chinese populations. Further, trans-ethnic comparison suggests population-specific effect or allelic heterogeneity for 11 loci. These population-specific effects contribute significantly to the ethnic diversity of psoriasis prevalence. This study not only provides novel biological insights into the involvement of immune and keratinocyte development mechanism, but also demonstrates a complex and heterogeneous genetic architecture of psoriasis susceptibility across ethnic populations.

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.

Engaging global key opinion leaders, the International Psoriasis Council (IPC) held a day-long roundtable discussion with the primary purpose to discuss the treatment goals of psoriasis patients and worldwide barriers to optimal care. Setting clear expectations might ultimately encourage undertreated psoriasis patients to seek care in an era in which great gains in therapeutic efficacy have been achieved. Here, we discuss the option for early treatment of all categories of psoriasis to alleviate disease impact while emphasizing the need for more focused attention for psoriasis patients with mild and moderate forms of this autoimmune disease. In addition, we encourage policy changes to keep pace with the innovative therapies and clinical science and highlight the demand for greater understanding of treatment barriers in resource-poor countries.

Inflammatory skin diseases including atopic dermatitis (AD) and psoriasis (PSO) are underpinned by dendritic cell (DC)–mediated T cell responses. Currently, the heterogeneous human cutaneous DC population is incompletely characterized, and its contribution to these diseases remains unclear. Here, we performed index-sorted single-cell flow cytometry and RNA sequencing of lesional and nonlesional AD and PSO skin to identify macrophages and all DC subsets, including the newly described mature LAMP3+BIRC3+ DCs enriched in immunoregulatory molecules (mregDC) and CD14+ DC3. By integrating our indexed data with published skin datasets, we generated a myeloid cell universe of DC and macrophage subsets in healthy and diseased skin. Importantly, we found that CD14+ DC3s increased in PSO lesional skin and co-produced IL1B and IL23A, which are pathological in PSO. Our study comprehensively describes the molecular characteristics of macrophages and DC subsets in AD and PSO at single-cell resolution, and identifies CD14+ DC3s as potential promoters of inflammation in PSO.

A working group of dermatologists in Asian countries assessed the current status of psoriatic management in the region to prepare a consensus report on topical treatment in mild to moderate plaque psoriasis. Even though the association of psoriasis with systemic comorbidities is increasingly acknowledged, psoriasis is still lower in health‐care priority lists in the region. The psychosocial impact of psoriasis may be greater in Asian countries due to cultural norms and social discrimination. Non‐adherence to treatment is also common among Asians. The current care given to patients with mild to moderate psoriasis needs to be streamlined, enhanced and organized with a patient‐centered care approach to achieve better outcomes. A comprehensive assessment of the disease severity and its impact on a patient's life is required before initiating treatment. Education and active involvement of the patient in the treatment plan is an important part of psoriatic management. It is recommended to personalize topical treatment to meet the needs of the patient, depending on disease severity, psychosocial impact, the patient's expectations and, more importantly, the patient's willingness and ability to actively follow the treatment procedure. Fixed‐dose combination of corticosteroid and vitamin D analogs is the preferred topical medication for both initial and maintenance phases of treatment. The fast containment of the disease is the goal of the initial phase of 4–8 weeks and it demands a potent fast‐acting topical therapy. Satisfactory control of the disease and prevention of relapses should be achieved during the maintenance phase with twice a week or weekend applications.

This study demonstrates the strong psychiatric morbidity in patients with psoriasis, for which further psychiatric evaluation should be considered.

Psoriasis (OMIM#177900) is a common polygenic skin disorder affecting approximately 2% of the northern European population and 0.1% of the Han Chinese. Psoriasis patients suffer from chronic skin inflammation, manifested by erythematous scaly lesions. PSORS1-PSORS9 have been confirmed as psoriasis susceptibility loci in independent genetic studies on predominantly Caucasian populations, with psoriasis susceptibility loci (PSORS1, PSORS9) and additional loci at 9q33-34 and 2p22.3-11.2 reported in Han Chinese patients. In this study, we show the association of PSORS4 with psoriasis in Singaporean Chinese. Dense genotyping of single-nucleotide polymorphism-tagging candidate genes within the epidermal differentiation complex revealed significant association in the proximity of the involucrin gene (IVL); the strongest association was seen in early-onset psoriasis patients (P=0.0014). A follow-up genome-wide association screen localized the psoriasis susceptibility region to approximately 360 kb along chromosome 1 in the vicinity of IVL, small proline-rich region (SPRR) and proline-rich region 9 (PRR9) genes. The study of interactions between the causative variant(s) in this locus will provide insights into a possible role for epidermal barrier formation in the pathogenesis of psoriasis.

Our study suggests that sunscreen is the most common photoallergen to date as opposed to musk ambrette, which was the most common photoallergen in our earlier study in 1991-1993. This finding is similar to the recent European Multicentre Photopatch Test Study.