A catalog of potential putative functional variants in psoriasis genome-wide association regions

Functional Genomics in Psoriasis

Psoriasis is an autoimmune cutaneous condition that significantly impacts quality of life and represents a burden on society due to its prevalence. Genome-wide association studies (GWASs) have pinpointed several psoriasis-related risk loci, underlining the disease's complexity. Functional genomics is paramount to unveiling the role of such loci in psoriasis and disentangling its complex nature. In this review, we aim to elucidate the main findings in this field and integrate our discussion with gold-standard techniques in molecular biology-i.e., Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)-and high-throughput technologies. These tools are vital to understanding how disease risk loci affect gene expression in psoriasis, which is crucial in identifying new targets for personalized treatments in advanced precision medicine.

Polymorphisms in the CD6-ALCAM axis may modulate psoriasis risk and outcomes

The fact that CD6, along with its ligand - ALCAM, plays a role in regulating T cell activation makes the genes encoding these molecules promising candidates for research in T cell-mediated diseases such as psoriasis vulgaris (PsV). Our study aimed to determine whether CD6 (rs17824933C>G, rs11230563C>T and rs12360861G>A) and ALCAM (rs6437585C>T, rs11559013G>A) polymorphisms may affect psoriasis susceptibility and severity (assessed by Psoriasis Area and Severity Index (PASI)). Moreover, the presence of HLA-C*06:02, the strongest psoriasis risk factor in the Caucasian population, was also investigated. 273 patients diagnosed with psoriasis vulgaris and 256 blood donors with no history of PsV or other dermatoses were included in this study. Genotyping of the investigated polymorphisms was carried out using the allelic discrimination method with the application of TaqMan SNP Genotyping Assays. We observed the association of rs17824933G allele with a higher psoriasis risk in HLA-C*06:02(+) individuals (CG + GG vs CC, OR = 1.87, CI95% = 1.03; 3.37, p = 0.0350). Furthermore, we found a difference in average PASI score among groups of patients divided according to the number of CD6 and ALCAM polymorphic sites with minor alleles (F2,173 = 6.159, p = 0.0026). Collectively, our findings suggest that polymorphisms of CD6-ALCAM axis genes may modulate psoriasis risk and outcomes.

Rare coding variants in NOX4 link high ROS levels to psoriatic arthritis mutilans

Psoriatic arthritis mutilans (PAM) is the rarest and most severe form of psoriatic arthritis, characterized by erosions of the small joints and osteolysis leading to joint disruption. Despite its severity, the underlying mechanisms are unknown, and no susceptibility genes have hitherto been identified. We aimed to investigate the genetic basis of PAM by performing massive parallel sequencing in sixty-one patients from the PAM Nordic cohort. We found rare variants in the NADPH oxidase 4 (NOX4) in four patients. In silico predictions show that the identified variants are potentially damaging. NOXs are the only enzymes producing reactive oxygen species (ROS). NOX4 is specifically involved in the differentiation of osteoclasts, the cells implicated in bone resorption. Functional follow-up studies using cell culture, zebrafish models, and measurement of ROS in patients uncovered that these NOX4 variants increase ROS levels both in vitro and in vivo. We propose NOX4 as the first candidate susceptibility gene for PAM. Our study links high levels of ROS caused by NOX4 variants to the development of PAM, offering a potential therapeutic target.

Variants in PRKCE and KLC1, Potential Regulators of Type I Psoriasis

Purpose

Psoriasis is a multifactorial disease with a complex genetic predisposition. The pathophysiology of psoriasis is associated with genetic variants. To better characterize gene variants in psoriasis and identify the relationship between clinical characteristics and variant genes in its pathogenesis.

Patients and Methods

DNA was extracted and purified from eight pairs of monozygotic twins with psoriasis discordance and 282 type I psoriasis patients. Thirteen variable genes were amplified and sequenced using the Sanger method after whole genome sequencing.

Results

Thirteen genes were found to be variable in eight pairs of monozygotic twins with psoriasis discordance. Among the 13 genes, the variant frequencies of protein kinase C epsilon (PRKCE) (c.240T>C, 35.9% vs 47.7%, P < 0.05) and kinesin light chain 1 (KLC1) (c.216A>G, 2.9% vs 98.1%, P< 0.01) were significantly lower in psoriasis than in normal Asian individuals. Additionally, we found considerable differences in the relationship between variants in genes CADM2, JPH2, SPTLC3 and clinical characteristics stratified by medical history and family history. Moreover, the variants in MEGF6 (39.52% vs 22.50%, χ²=3.83, p < 0.05) showed a stronger association with the mild group (PASI ≤10) than the heavy group.

Conclusion

Our results provide a comprehensive correlation analysis of regulatory genes that are regulated in psoriasis. This integrated analysis offers novel insight into the pathogenic mechanisms involved in psoriasis.

Psoriasis and Genetics

Psoriasis is a common inflammatory skin disease caused by the interplay between multiple genetic and environmental risk factors. This review summarises recent progress in elucidating the genetic basis of psoriasis, particularly through large genome-wide association studies. We illustrate the power of genetic analyses for disease stratification. Psoriasis can be stratified by phenotype (common plaque versus rare pustular variants), or by outcome (prognosis, comorbidities, response to treatment); recent progress has been made in delineating the genetic contribution in each of these areas. We also highlight how genetic data can directly inform the development of effective psoriasis treatments.