Background: Acne inversa/hidradenitis suppurativa (HS) is a chronic, recurrent inflammatory disease of the skin that can significantly affect patients’ quality of life. The etiology and pathogenesis of HS are unclear and gene mutations might play a role. Summary: The primary focus of the review is on aggregating the gene mutations reported, summarizing the structure of γ-secretase and analyzing and speculating about the mechanism and the underlying relations between gene mutation and functional changes of protein. The systematic literature review was done by searching the PubMed, Embase, and Web of Science databases. γ-Secretase is an intramembrane protease complex responsible for the intramembranous cleavage of more than 30 type-1 transmembrane proteins including amyloid precursor protein and Notch receptors. The protein complex consists of four hydrophobic proteins: presenilin, presenilin enhancer-2 (PSENEN), nicastrin, and anterior pharynx defective 1 (APH1). To date, 57 mutations of γ-secretase genes have been reported in 70 patients or families worldwide, including 39 in NCSTN, 14 in PSENEN, and 4 in PSEN1, of which 17 are frameshifts, 15 result in nonsense mutations, 13 in missense mutations, and 12 are splice site mutations. Given the structure of γ-secretase and analysis of related mutation loci of NCSTN, PSENEN, and PSEN1, mutations in γ-secretase genes could affect activation of presenilin, prevent substrate binding, and hinder intramembrane cleavage of select proteins.

The SAPHO syndrome is a group of disorders that manifest as synovitis, acne, pustulosis, hyperostosis, and osteitis. Of these, acne damage can present as acne conglobata, acne fulminans, or hidradenitis suppurativa (HS).

Objective: This study was performed to estimate the prevalence of hidradenitis suppurativa (HS) in China and describe the demographic and clinical features of HS in the Chinese population. Methods: This multicenter clinic-based cross-sectional study was conducted in dermatology clinics within 19 hospitals located in 15 cities/provinces across China from September to October 2020. The prevalence of HS was calculated as the percentage of patients with HS among all visitors at participating clinics during the 1-month study period. HS was independently diagnosed by two certified dermatologists at each site. All visitors at participating clinics were screened, and all patients with HS were invited to participate in a questionnaire survey to elucidate the demographics and clinical features of HS in the Chinese population. Results: We identified 92 patients with HS among 274,742 visitors at participating clinics. The prevalence rate was 0.03349% or 33.49 per 100,000 population (95% confidence interval, 26.64-40.32), and the female:male ratio was 1.0:4.7. Conclusion: The overall prevalence of HS in China was lower than that in Western and other Asian countries with a predominance of male patients.