Evidence of gene-gene interaction in Hidradenitis suppurativa - A nationwide register study of Danish twins

Unravelling the complex pathogenesis of hidradenitis suppurativa

Hidradenitis suppurativa (HS) is a complex inflammatory disease, with rapid advances being made in our understanding of the complex immunological pathogenesis of the condition. New insights into the genomic landscape of HS have identified a number of genes that contribute to the development of HS in a polygenic manner, contributing to inflammatory dysregulation and alterations in epidermal stem cell fate in the follicular unit. These genomic variations can explain unique aspects of the disease such as the development and presence of epithelialized tunnels and abnormalities in wound healing. From genetic and translational studies, it is likely that these genetic alterations predispose to an innate immune dysregulation that can be triggered through sex hormone-responsive transcription factors with hormonal changes such as puberty, pregnancy and the menstrual cycle. The role of sex hormones in HS also has direct effects upon the development and maturation of inflammatory cells such as monocytes, which has the potential to explain differential patient response to treatments such as interleukin-23 antagonism. The role of adipose tissue as an active immunological organ also plays a role in the immune dysregulation seen in the disease. Fibrotic tissue and immunologically active fibroblasts play a significant role in the perpetuation of inflammation and development of adaptive immune dysfunction in the disease. The cutaneous and gut microbiomes play significant roles in the activation of innate immunity, although conflicting data exist as to their central or peripheral role in disease pathogenesis. Overall, our understanding of disease pathogenesis in HS is moving toward a more nuanced, complex paradigm in which patient heterogeneity in presentation and immunological characteristics are moving closer to the identification of therapeutic biomarkers to guide therapeutic modalities in the management of this burdensome condition.

Hidradenitis suppurativa

Hidradenitis suppurativa is a chronic inflammatory disease characterised by painful, deep-seated nodules, abscesses, and draining tunnels in the skin of axillary, inguinal, genitoanal, or inframammary areas. In recent years, the body of knowledge in hidradenitis suppurativa has advanced greatly. This disorder typically starts in the second or third decade of life. The average worldwide prevalence is 1% but varies geographically. Hidradenitis suppurativa has a profound negative effect on patients' quality of life and on the gross value added to society. Comorbidities (eg, metabolic syndrome, inflammatory arthritis, and inflammatory bowel disease) frequently accompany skin alterations, because of systemic inflammation. Pathogenesis of hidradenitis suppurativa is complex and includes innate immune mechanisms (eg, macrophages, neutrophils, IL-1β, tumour necrosis factor [TNF], and granulocyte colony-stimulating factor), T-cell mechanisms (eg, IL-17 and IFN-γ), and B-cell mechanisms (eg, associated with dermal tertiary lymphatic structures and autoantibodies). Chronic inflammation leads to irreversible skin damage with tunnel formation and morbid scarring. Current treatment includes drug therapy (for the initial, purely inflammatory phase), combined drug and surgical therapy (for the destructive phase), or surgery alone (for the burnout phase). The first systemic therapies approved for hidradenitis suppurativa targeting TNF (adalimumab) and IL-17 (secukinumab and bimekizumab) have expanded drug therapy options for moderate-to-severe disease, which were previously mainly restricted to oral antibiotics. Moreover, there is a robust pipeline of immunomodulatory drugs in various stages of development for hidradenitis suppurativa. Aims of management should include early intervention to prevent irreversible skin damage, adequate control of symptoms including pain, and mitigation of extra-cutaneous comorbidities, all requiring early diagnosis and an interdisciplinary, holistic and personalised approach.

A genome-wide association meta-analysis links hidradenitis suppurativa to common and rare sequence variants causing disruption of the Notch and Wnt/β-catenin signaling pathways

BACKGROUND

The contributions of genetic and environmental risk factors to hidradenitis suppurativa (HS) are both poorly understood.

OBJECTIVE

To identify sequence variants that associate with HS and determine the contribution of environmental risk factors and inflammatory diseases to HS pathogenesis.

METHODS

A genome-wide association meta-analysis of 4814 HS cases (Denmark: 1977; Iceland: 1266; Finland: 800; UK: 569; and US: 202) and 1.2 million controls, searching for sequence variants associated with HS.

RESULTS

We found 8 independent sequence variants associating with HS, 6 common and 2 rare (frequency <1%). Four associations point to candidate causal genes, NCSTN, PSENEN, WNT10A, and TMED10, that all map to the Notch and Wnt/β-catenin signaling pathways, involved in epidermal keratinization.

LIMITATIONS

Limited racial diversity may prevent identification of sequence variants of particular importance in non-Caucasian populations.

CONCLUSIONS

These findings demonstrate that genes and pathways involved in epidermal keratinization are the genetic backbone of HS pathology.

Intrinsic factors in the pathogenesis of hidradenitis suppurativa: Genetics, hormones, and the microbiome

The pathogenesis of hidradenitis suppurativa is complex and multifaceted. Our understanding of disease mechanisms is in constant flux with new genetic, inflammatory, and microbiological insights upending previous paradigms and enlightening us as to the complex connections between different drivers of disease. This updated review integrates novel genetic insights from genome wide association studies, along with novel basic science data from single cell transcriptomic studies and recent interventional translational work to inform our evolving understanding of the disease. The overarching premise is that hidradenitis suppurativa is a chronic autoinflammatory disorder characterized by inflammatory dysregulation in a background of stem cell fate aberrations highly responsive to hormonal and metabolic changes. Genetic drivers are linked to both hair follicle stem cell fate and cellular response to androgen signaling. The complex mixed inflammatory circuits involve both innate and adaptive immunity, with activation of inflammatory fibroblast subsets and tertiary lymphoid organs in chronic disease. Interplay between inflammation, the cutaneous and gut microbiomes are observed both pre- and posttherapy, however causality remain unclear. Metabolic syndrome, sex hormones and insulin resistance are all interlinked, with adipose tissue being a hormonally active organ able to modulate endogenous sources of sex hormones. Future enquiry regarding factors contributing to disease progression and the identification of novel therapeutic targets will aid in more effective therapeutic strategies for management of this burdensome disease.

Comprehensive Catalog of Variants Potentially Associated with Hidradenitis Suppurativa, Including Newly Identified Variants from a Cohort of 100 Patients

Hidradenitis suppurativa (HS) is a chronic skin disease characterized by painful, recurrent abscesses, nodules, and scarring, primarily in skin folds. The exact causes of HS are multifactorial, involving genetic, hormonal, and environmental factors. It is associated with systemic diseases such as metabolic syndrome and inflammatory bowel disease. Genetic studies have identified mutations in the γ-secretase complex that affect Notch signaling pathways critical for skin cell regulation. Despite its high heritability, most reported HS cases do not follow a simple genetic pattern. In this article, we performed whole-exome sequencing (WES) on a cohort of 100 individuals with HS, and we provide a comprehensive review of the variants known to be described or associated with HS. 91 variants were associated with the γ-secretase complex, and 78 variants were associated with other genes involved in the Notch pathway, keratinization, or immune response. Through this new genetic analysis, we have added ten new variants to the existing catalogs. All variants are available in a .vcf file and are provided as a resource for future studies.

Comorbidities, Clinical Presentation, Subtypes, and Treatment of HS Patients in Lithuania

Background: Hidradenitis suppurativa (HS) is a persistent, recurring skin inflammatory condition linked to various comorbidities. Management involves antibiotics, hormone therapy, immune-modulating drugs, surgery, and treatment of comorbidities. The objectives of the study were to assess the comorbidities, clinical presentation subtypes, and applied treatment of patients with HS. Methods: Patients with HS who visited the Centre of Dermatovenereology at Vilnius University Hospital Santaros Klinikos in Lithuania underwent evaluation based on the guidelines of the European Hidradenitis Suppurativa Foundation Registry questionnaire. Results: The study included 49 patients, and 61.22% (n = 30) had comorbidities. A strong positive correlation was found between a family history of inflammatory diseases (69.38% (n = 34)) and the severity of HS according to Hurley stage (r = 0.71 p < 0.05). A statistically significant correlation (r = 0.944, p = 0.02) was found between metabolic comorbidities and Hurley stage. Patients on biologic treatment had a mean IHS4 of 7.38 at the beginning of treatment and 3.22 at follow-up (p < 0.05). For patients not on biologics, the initial IHS4 score was 6.21 and 5.42 at follow-up (p > 0.05). Conclusions: A family history of inflammatory diseases and metabolic comorbidities showed a strong correlation with HS severity. Treatment with biologics showed significant improvement in HS scores compared to systemic antibiotics.

Hidradenitis suppurativa and cardiovascular diseases: A bidirectional Mendelian randomization study

BACKGROUND

Prior investigation has indicated a link between Hidradenitis suppurativa (HS) and cardiovascular diseases (CVDs), yet the causal relationship (CR) between these conditions remains unresolved.

METHODS

This investigation utilized bidirectional Mendelian randomization (MR) analysis to determine the CR between HS and CVDs. Genetic instruments for both conditions were sourced from genome-wide association studies (GWAS). The GWAS summary data for CVD comprised coronary artery disease (CAD), myocardial infarction (MI), coronary atherosclerosis (CA), ischemic stroke (IS), and chronic heart failure (CHF). Four new approaches were added to the inverse variance weighted (IVW) method for the main analysis: weighted median, weighted MR-Egger, simple mode, and weighted mode. The validity of the causal conclusions was verified by sensitivity tests that included leave-one-out analysis, heterogeneity, and pleiotropy.

RESULTS

HS and CAD (OR = 1.024; 95%CI: 1.002-1.046, P = 0.033), MI (OR = 1.001; 95%CI: 1.000-1.002, P = 0.033), and CA (OR = 1.001; 95%CI: 1.000-1.002, P = 0.022) were identified to have a positive CR, according to the IVW analysis. Conversely, no significant association was identified between HS and either IS or CHF. Furthermore, the bidirectional analysis indicated no reverse causation between these diseases.

CONCLUSION

The findings of this study suggest a potential CR between HS and CAD, MI, and CA. Additional research is warranted to elucidate the biological mechanisms underlying these associations.

Genetic factors associated with hidradenitis suppurativa, a literature review

Background

Hidradenitis suppurativa (HS) is a chronic inflammatory disease characterized by deep-seated, painful lesions most frequently occurring in intertriginous areas of the skin. HS leads to poor quality of life in affected individuals and is difficult to diagnose and treat.

Objective

Understanding the genetics associated with familial inheritance may lead to a better understanding of the pathogenesis of this debilitating disease.

Methods

Articles published until March 9, 2023, were identified in PubMed using the following search terms: hidradenitis suppurativa and gene* or acne inversa and gene*.

Results

The rate of monogenic mutations associated with HS is less than 7%, with the most common genetic mutations reported in sporadic and familial HS cases being in NCSTN and less frequently in PSENEN. Individuals with mutations in the gamma-secretase complex tended to have more severe HS and an early age of onset.

Limitations

This study was limited to the case studies available in PubMed, the majority of which used targeted gene panels to detect genetic mutations.

Conclusion

Approximately 30% of individuals diagnosed with HS report having a positive family history; however, very few studies demonstrate monogenic familial transmission of HS. The case studies of syndromic HS reported a variety of genetic mutations associated with HS, some of which were familial, while others were sporadic, suggesting that other pathways may be involved in the pathogenesis of HS and other potential mutations that have yet to be evaluated. More research is needed to understand the genetic mutations in HS.

Initial steps towards developing a predictive algorithm of disease progression for hidradenitis suppurativa (HS): results from a Cox proportional hazard regression analysis on disease progression among a cohort of 335 Danish patients with HS

BACKGROUND

Hidradenitis suppurativa (HS) is a chronic inflammatory and scarring disease with a wide spectrum of disease severity. The amount of scarring is proportional to the preceding tissue damage and poses a challenge to patients. Severe HS is most often treatment recalcitrant, but hypothetically avoidable through early biologic treatment. Early prediction of individual risk of disease progression is therefore essential for patient management.

OBJECTIVES

To investigate risk factors associated with disease progression and to design an algorithm capable of predicting disease -progression.

METHODS

A prospective cohort study of 335 Hurley III-naïve patients with HS, not treated with biologics, was followed for a median of 2 years. Potential risk factors covered basic demographics, HS anamnestic factors and clinical HS factors collected during physical examination. Two separate Cox proportional hazard regression (CPHR) analyses were conducted. A summated 'progression score' was calculated and used in the predictive algorithm of severe disease. Subsequent bootstrap sampling was used to validate the predictability of the predictive algorithm.

RESULTS

The CPHR analysis of Transition to severe disease found that active smoking [hazard ratio (HR) 4.01, 95% confidence interval (CI) 1.71-9.40, P = 0.001]; body mass index (BMI) points > 25 at baseline (each point: HR 1.06, 95% CI 1.02-1.09, P < 0.001); active disease in 2 (HR 4.26, 95% CI 1.23-14.84, P = 0.02) and ≥ 3 areas (HR 6.54, 95% CI 1.89-22.72, P = 0.003) all constituted substantial risk factors. Conversely, the CPHR analysis of Disease progression did not yield results of clinical relevance. A 'progression score' of 3.04 was used as a threshold in the predictive algorithm of Transition to severe disease and achieved the following test specifics: sensitivity = 0.51, specificity = 0.86, positive predictive value = 0.50, negative predictive value = 0.86.

CONCLUSIONS

We found a disparity between factors increasing the risk of simple Disease progression and those increasing the risk of Transition to severe disease. For the latter, active smoking, BMI points > 25, active disease in 2 or ≥ 3 areas were all shown to be the clinically relevant factors that could be used to construct an algorithm that correctly predicted progression to severe HS in more than half of all instances.

Increased cancer incidence among patients with hidradenitis suppurativa - a Danish nationwide register study 1977-2017

BACKGROUND

The chronic, inflammatory skin disease hidradenitis suppurativa (HS) (prevalence: 0.5%-1%, diagnostic delay: 7-10 years) primarily arises in younger adults and frequently coincides with autoimmune comorbidities and unhealthy life-styles (smoking and obesity). These factors are known to increase cancer risk, but despite this, information on cancer occurrence among HS patients is scarce.

MATERIALS AND METHODS

A nationwide retrospective register-based study assessing relative risk of cancer - overall and by anatomical site - following HS diagnosis expressed as standardized incidence ratios (SIRs), which is ratios between observed cases among all Danes diagnosed with HS since 1977 and expected cases based on cancer incidence rates of the entire Danish population during the same period.

RESULTS

Participants consisted of a cohort of 13,919 Danes with HS, who during an average of 14.2 years of follow-up developed a total of 1,193 incident cancers, corresponding to a 40% increased risk (SIR = 1.4, 95% CI: 1.3 to 1.4, p < 0.001). Increased risks were observed for cancers of the respiratory system, oral cavity and pharynx, digestive organs and peritoneum, urinary tract, and the lymphatic tissues.

INTERPRETATION

These findings underline an unmet need for health monitoring, lifestyle interventions and cancer screening if and when relevant.

Hidradenitis suppurativa: Detangling phenotypes and identifying common denominators

Hidradenitis suppurativa (HS) is a chronic inflammatory skin disease with a severe impact on patients' quality of life through its recurrent and painful nature, as well as its comorbidity burden. The shift in the pathogenic paradigm from a condition of the apocrine glands to an autoinflammatory disease associated with follicular destruction has rendered its understanding difficult, as there are still large gaps in pinpointing the underlying mechanisms, which cannot currently explain the existing clinical variation and as a result, translate into suboptimal therapy. Multifactorial involvement is hypothesized, with an implication of genetic mutations, microbiome dysbiosis, cytokine upregulation and environmental factors. Clinical observation is fundamental for diagnosis, however, the marked heterogeneity in presentation leads to delays in detection and challenges in treatment selection, showcasing clear limits in defining the link between genetic aspects of HS, the role of epigenetic factors and its pathogenic pathways. There have been attempts to formulate phenotypes that could aid in prognostication and management, however, current classification schemata show significant overlap and no validation through longitudinal studies. In this context, nomenclature poses a great challenge due to the lack of global agreement in the definition of lesions, which should be addressed by future research to enable simplified recognition and allow for more precise severity scoring. This could be complemented by the addition of extra dermatologic findings or paraclinical assessment in constructing phenotypes. The development of valid, predictive and reliable classifications of HS may lead to an improvement in comprehending its pathophysiology, favouring a more personalized approach in management. This could be achieved through consensus in the characterization of clinical features and data gathering, as well as validation attempts for described phenotypes. Ultimately, the genotype-endotype-phenotype correlation in HS requires targeted, systematic inquiries and should be addressed more largely to broaden the perspective on this debilitating entity.

NCSTN In-Frame Deletion in Maltese Patients With Hidradenitis Suppurativa

Importance

Hidradenitis suppurativa (HS) is a complex trait that has a monogenic etiology in a subset of patients. Variation in genes that encode proteins of the γ secretase complex, particularly NCSTN, account for few patients who exhibit familial forms of HS. Thus far, extensive genotype-phenotype correlations have been lacking.

Objective

To establish the prevalence of the NCSTN:c.671_682del variant and explore potential genotype-phenotype associations in an ethnically Maltese HS cohort.

Design, Setting, and Participants

This cross-sectional study conducted from December 2021 to September 2022 included patients 18 years or older with a diagnosis of HS as defined by recurrent nodules, abscesses, and/or draining tunnels in typical (axilla, breast, groin, buttock, thighs, and inframammary folds) and less typical (scalp, ear pinnae, neck, arms, antecubital fossae) sites who were recruited from the sole national dermatology reference center servicing the Maltese archipelago. Clinical examination and targeted genetic analysis for an NCSTN deletion that was originally identified through whole-exome sequencing in a family with multigenerational disease were performed.

Exposure

Recruited patients were phenotyped and genotyped for the NCSTN:c.671_682del variant.

Main Outcome and Measures

To determine the prevalence of the NCSTN:c.671_682del variant and establish possible genotype-phenotype associations in the ethnically Maltese HS cohort.

Results

A total of 113 patients with HS (56 women [49.6%]) met the inclusion criteria and were enrolled in this study. The median age of disease onset was 18 years (range, 7-62 years), and the median International Hidradenitis Suppurativa Severity Score System score was 4.39 (range, 1.0-64.0). The NCSTN variant was identified in the heterozygous state in 14 patients (12.4%) from 5 unrelated, nonconsanguineous families of Maltese ethnicity. The variant was not identified in an ethnically matched reference genomic data set of disease-free individuals. Variant carriers manifested HS symptoms earlier and were more likely to exhibit a distinctive HS phenotype, which was characterized by involvement of the scalp, neck, torso, and antecubital fossae. Despite manifesting similar clinical disease severity, variant carriers were more likely to require treatment with adalimumab.

Conclusions and Relevance

The results of this cross-sectional study suggest that monogenic variation in NCSTN is associated with HS in a subset of patients who have a distinct, atypical phenotype.

The genetic aspects of hidradenitis suppurativa

Genetic aspects have a substantial role in hidradenitis suppurativa (HS) pathogenesis. A positive family history of HS occurs in about one-third of HS cases and is significantly higher in patients with early onset of the disease. Recent twin studies have shown a high heritability in HS, fortifying the importance of genetic factors in disease pathogenesis. Based on existing knowledge on the genomics of HS, the disease can be categorized as familial HS, sporadic, syndromic HS, and "HS plus" associated with other syndromes. In familial HS, autosomal dominant transmission is proposed, and monogenic inheritance is rare. This monogenic trait is related to mutations of γ-secretase component genes and Notch signaling or defects in inflammasome function. With newly discovered gene mutations, such as those related to innate and adaptive immunity, skin microbiome, inflammasome, epidermal homeostasis, and keratinization pathway, we can define HS as a polygenic, multifactorial, autoinflammatory disease. To fully elucidate the genetic aspects of HS, we need extensive, long-term global collaborations.

Genetic Variants Associated With Hidradenitis Suppurativa

Importance

Hidradenitis suppurativa (HS) is a common and severely morbid chronic inflammatory skin disease that is reported to be highly heritable. However, the genetic understanding of HS is insufficient, and limited genome-wide association studies (GWASs) have been performed for HS, which have not identified significant risk loci.

Objective

To identify genetic variants associated with HS and to shed light on the underlying genes and genetic mechanisms.

Design, Setting, and Participants

This genetic association study recruited 753 patients with HS in the HS Program for Research and Care Excellence (HS ProCARE) at the University of North Carolina Department of Dermatology from August 2018 to July 2021. A GWAS was performed for 720 patients (after quality control) with controls from the Add Health study and then meta-analyzed with 2 large biobanks, UK Biobank (247 cases) and FinnGen (673 cases). Variants at 3 loci were tested for replication in the BioVU biobank (290 cases). Data analysis was performed from September 2021 to December 2022.

Main Outcomes and Measures

Main outcome measures are loci identified, with association of P < 1 × 10-8 considered significant.

Results

A total of 753 patients were recruited, with 720 included in the analysis. Mean (SD) age at symptom onset was 20.3 (10.57) years and at enrollment was 35.3 (13.52) years; 360 (50.0%) patients were Black, and 575 (79.7%) were female. In a meta-analysis of the 4 studies, 2 HS-associated loci were identified and replicated, with lead variants rs10512572 (P = 2.3 × 10-11) and rs17090189 (P = 2.1 × 10-8) near the SOX9 and KLF5 genes, respectively. Variants at these loci are located in enhancer regulatory elements detected in skin tissue.

Conclusions and Relevance

In this genetic association study, common variants associated with HS located near the SOX9 and KLF5 genes were associated with risk of HS. These or other nearby genes may be associated with genetic risk of disease and the development of clinical features, such as cysts, comedones, and inflammatory tunnels, that are unique to HS. New insights into disease pathogenesis related to these genes may help predict disease progression and novel treatment approaches in the future.

Inborn Errors of Immunity in Hidradenitis Suppurativa Pathogenesis and Disease Burden

Hidradenitis suppurativa (HS), also known as Verneuil's disease and acne inversa, is a prevalent, debilitating, and understudied inflammatory skin disease. It is marked by repeated bouts of pathological inflammation causing pain, hyperplasia, aberrant healing, and fibrosis. HS is difficult to manage and has many unmet medical needs. There is clinical and pharmacological evidence for extensive etiological heterogeneity with HS, suggesting that this clinical diagnosis is capturing a spectrum of disease entities. Human genetic studies provide robust insight into disease pathogenesis. They also can be used to resolve etiological heterogeneity and to identify drug targets. However, HS has not been extensively investigated with well-powered genetic studies. Here, we review what is known about its genetic architecture. We identify overlap in molecular, cellular, and clinical features between HS and inborn errors of immunity (IEI). This evidence indicates that HS may be an underrecognized component of IEI and suggests that undiagnosed IEI are present in HS cohorts. Inborn errors of immunity represent a salient opportunity for rapidly resolving the immunological landscape of HS pathogenesis, for prioritizing drug repurposing studies, and for improving the clinical management of HS.

A Case of Concurrent Psoriasis and Hidradenitis Suppurativa Successfully Treated with Tildrakizumab

INTRODUCTION

Plaque psoriasis and hidradenitis suppurativa are chronic inflammatory skin conditions with common pathogenetic pathways.

METHODS

We report the case of a 38-year-old man with 15-year history of psoriasis and hidradenitis suppurativa successfully treated with tildrakizumab for both conditions. After treatment failure to adalimumab, secukinumab, and guselkumab, tildrakizumab therapy was initiated and resulted in complete remission of psoriasis and the achievement of hidradenitis suppurativa clinical response after 40 weeks, without reporting adverse events. These responses were maintained at week 52.

CONCLUSION

Tildrakizumab may be an effective and safe therapeutic option for concomitant psoriasis and hidradenitis suppurativa.

Causal association between inflammatory bowel disease and hidradenitis suppurativa: A two-sample bidirectional Mendelian randomization study

Background

Epidemiological studies have revealed a link between inflammatory bowel disease (IBD) and hidradenitis suppurativa (HS). To determine whether IBD and HS are causally related, we used the Mendelian randomization (MR) approach.

Methods

A two-sample MR was performed using an analysis of 12,882 patients and 21,770 controls with IBD and its main subtypes, ulcerative colitis (UC) and Crohn's disease (CD). A total of 409 cases and 211,139 controls without hidradenitis suppurativa (HS) were included in the data for this condition from various GWAS investigations. Odds ratios (ORs) with 95% confidence intervals (CIs) are used to estimate causal effects.

Results

The study assessed the causal relationship between HS and IBD in both directions. The risk of HS was increased by IBD (IVW OR = 1.34, 95% CI = 1.20-1.49, p = 2.15E-07) and, in addition, HS was affected by UC (IVW OR = 1.27, 95% CI = 1.13-1.43, p = 8.97E-04) and CD (IVW OR = 1.18, 95% CI = 1.08-1.29, p = 4.15E-04). However, there was no evidence of a causal relationship between HS and IBD or its subtypes (IBD IVW OR = 1.00, 95% CI = 0.96-1.05, p = 0.85; UC IVW OR = 0.99, 95% CI = 0.95-1.03, p = 0.65; CD IVW OR = 1.03, 95% CI = 0.98- 1.07, p = 0.28).

Conclusion

This study demonstrates that IBD and its subtypes have a causal effect on HS, whereas HS does not affect IBD. Gut-skin axis interactions may help to understand this association. Nevertheless, further studies are needed to clarify the pathophysiology of the causal relationship between IBD and HS.

Interpreting the spectrum of gamma-secretase complex missense variation in the context of hidradenitis suppurativa—An in-silico study

Hidradenitis suppurativa (HS) is a disease of the pilosebaceous unit characterized by recurrent nodules, abscesses and draining tunnels with a predilection to intertriginous skin. The pathophysiology of HS is complex. However, it is known that inflammation and hyperkeratinization at the hair follicle play crucial roles in disease manifestation. Genetic and environmental factors are considered the main drivers of these two pathophysiological processes. Despite a considerable proportion of patients having a positive family history of disease, only a minority of patients suffering from HS have been found to harbor monogenic variants which segregate to affected kindreds. Most of these variants are in the ɣ secretase complex (GSC) protein-coding genes. In this manuscript, we set out to characterize the burden of missense pathogenic variants in healthy reference population using large scale genomic dataset thereby providing a standard for comparing genomic variation in GSC protein-coding genes in the HS patient cohort.

Recent advances in hidradenitis suppurativa: Role of race, genetics, and immunology

Hidradenitis suppurativa (HS) is a multifactorial chronic skin disease characterized by inflammation around the hair follicles commonly affecting intertriginous areas. The underlying pathogenesis of HS and its molecular mechanisms are largely understudied. Genetic studies in families have identified variants within the γ-secretase complex associated with HS; however, no definitive genotype-phenotype correlations have been made. The lack of knowledge regarding the intersection of genetics, immunology and environmental risk factors is a major obstacle to improving treatment for patients with HS. This article provides an overview of the role of race, genetics, and immunology in HS to provide insight into the multiple factors influencing the pathophysiology of HS.

Hidradenitis Suppurativa: A Perspective on Genetic Factors Involved in the Disease

Hidradenitis Suppurativa (HS) is a chronic inflammatory skin disease of the pilosebaceous unit, clinically consisting of painful nodules, abscesses, and sinus tracts mostly in, but not limited to, intertriginous skin areas. HS can be defined as a complex skin disease with multifactorial etiologies, including-among others-genetic, immunologic, epigenetic, and environmental factors. Based on genetic heterogeneity and complexity, three different forms can be recognized and considered separately as sporadic, familial, and syndromic. To date, several genetic variants associated to disease susceptibility, disease-onset, and/or treatment response have been reported; some of these reside in genes encoding the gamma-secretase subunits whereas others involve autoinflammatory and/or keratinization genes. The aim of this perspective work is to provide an overview of the contribution of several genetic studies encompassing family linkage analyses, target candidate gene studies, and -omic studies in this field. In our viewpoint, we discuss the role of genetics in Hidradenitis suppurativa considering findings based on Sanger sequencing as well as the more recent Next Generation Sequencing (i.e., exome sequencing or RNA Sequencing) with the aim of better understanding the etio-pathogenesis of the disease as well as identifying novel therapeutic strategies.

Register, multicenter and genome-wide association studies in hidradenitis suppurativa

The European Hidradenitis Suppurativa Foundation (EHSF) e.V. has taken several initiatives to collaborative studies. They result from the data of the European Registry of Hidradenitis Suppurativa (ERHS) based on the knowledge obtained from the regional Northern countries (HISREG) and Italian (IRHIS) registries and the real-world data generated from claims data from insurance databases. Multicenter studies, such as the Hidradenitis Suppurativa collaborative study of subtypes (HORUS) and the Global Hidradenitis Suppurativa Atlas (GHISA) are planned to provide an ideal complement to the register studies. Most recently, the role of EHSF as a coordinator or key player is being explored in multiple genetic studies, such as a genome-wide association study (GWAS) and the exome sequencing and cellular/molecular profiling project, which will speed up gene and drug discovery in HS.

The Genomic Architecture of Hidradenitis Suppurativa-A Systematic Review

Hidradenitis suppurativa is a chronic, suppurative condition of the pilosebaceous unit manifesting as painful nodules, abscesses, and sinus tracts mostly in, but not limited to, intertriginous skin. Great strides have been made at elucidating the pathophysiology of hidradenitis suppurativa, which appears to be the product of hyperkeratinization and inflammation brought about by environmental factors and a genetic predisposition. The identification of familial hidradenitis suppurativa has sparked research aimed at identifying underlying pathogenic variants in patients who harbor them. The objective of this review is to provide a broad overview of the role of genetics in various aspects of hidradenitis suppurativa, specifically the pathophysiology, diagnosis, and clinical application.

Incidence and remission rates of self-reported hidradenitis suppurativa - A prospective cohort study conducted in Danish blood donors

BACKGROUND

A large discrepancy between physician-diagnosed and self-reported Hidradenitis suppurativa (HS) exists. Knowledge regarding incidence and remission rates of self-reported HS is missing, but may help bridge the gap in understanding between these two phenotypes.

OBJECTIVES

To determine the incidence and remission rates of self-reported HS, and to what degree these are affected by sex, smoking and BMI.

METHODS

A prospective cohort of 23 930 Danish blood donors. Information on self-reported HS, symptom-localisation, sex, age, BMI and smoking status was collected at baseline and study termination. Self-reported HS fulfilled clinical obligatory diagnostic criteria. Cox proportional hazards regression analyses were conducted for both incidence and remission rates providing a hazard ratio (HR) of risk for each variable in the regression.

RESULTS

Incidence rate of self-reported HS was 10.8/1000 person-years (95% confidence interval (CI): 9.9-11.7), decreasing as a function of numbers of areas affected. Female BMI points above 25 (HR = 1.11, 95% CI: 1.09-1.13), male BMI points above 25 (HR = 1.07, 95% CI: 1.04-1.11), active smoking (HR = 1.72, 95% CI: 1.15-2.57), male sex (HR = 0.55, 95% CI: 0.45-0.67) and years of age above 25 (HR = 0.97, 95% CI: 0.96-0.97) were all statistically associated with the development of self-reported HS. Remission rate of self-reported HS was 256.7/1000 person-years (95% CI: 223.9-292.6), decreasing as a function of numbers of affected areas. Symptoms in ≥3 areas (HR = 0.54, 95% CI: 0.34-0.85), active smoking (HR = 0.49, 95% CI: 0.32-0.76) and female weight loss (every percentage drop in BMI: HR = 1.07, 95% CI: 1.05-1.11) all significantly affected the remission rate.

CONCLUSIONS

Both incidence and remission rates of self-reported HS are high, indicating that many with self-reported HS are unlikely to be diagnosed, as they to a higher degree experience mild transient HS symptoms.