OBJECTIVES: The major histocompatibility complex class I chain-related gene A (MICA), a component of the human leukocyte antigen (HLA) gene complex, is involved in the pathogenesis of various diseases including cancers and autoimmune disorders. Rosacea, a chronic inflammatory skin disease with a complex pathogenesis, potentially influenced by genetic and autoimmune factors. This study aims to investigate the relationship among MICA gene polymorphisms, single nucleotide polymorphisms (SNPs), and susceptibility to rosacea, thereby offering new insights into the disease mechanism. METHODS: Peripheral blood DNA samples were collected from 84 patients with rosacea (rosacea group) and 223 healthy volunteers (control group) who visited the Dermatology Outpatient Department of Xiangya Hospital of Central South University between November 2017 and November 2019. MICA genotyping was performed using polymerase chain reaction-sequencing-based typing (PCR-SBT) and the next-generation sequencing (NGS), and the accuracy of the 2 methods was compared. The frequency distributions of MICA alleles between the 2 groups were analyzed. Amino acid clustering and SNP site analyses were conducted to identify haplotype-linked SNPs and to classify MICA polymorphic variants. Distribution differences of these classifications between groups were also examined. RESULTS: Blood tests in rosacea patients showed mildly elevated, with no significant changes in lymphocyte counts. Both PCR-SBT and NGS accurately identified MICA alleles. The most common alleles in the rosacea group were MICA*010:01, MICA*008:04, and MICA*019:01. The frequencies of MICA*002:01 and MICA*027 were significantly lower in the rosacea group compared to controls (6.55% vs 18.16% and 1.19% vs 5.38%, respectively), while and MICA*010:01 were significantly higher (7.74% vs 3.36% and 31.55% vs 18.61%, respectively; all P<0.05). Five short tandem repeat (STR) alleles were identified. Frequencies of MICA-A4 and MICA-A9 were lower in the rosacea group than in the control group (16.07% vs 23.32% and 7.74% vs 17.26%, respectively), whereas MICA-A6 was higher (10.12% vs 4.03%; all P<0.05). Clustering and SNP analysis identified 6 linked SNP sites, classifying MICA variants into Type I (C₃₆+M₁₂₉+K₁₇₃+G₂₀₆+W₂₁₀+S₂₁₅) and Type II (Y₃₆+V₁₂₉+E₁₇₃+S₂₀₆+R₂₁₀+T₂₁₅). Type I MICA variants were significantly associated with rosacea susceptibility. CONCLUSIONS MICA gene polymorphisms are associated with susceptibility to rosacea, and there are 6 linked SNP sites within the MICA gene. Based on this, MICA polymorphic variants are classified into Type I and Type II, with Type I being more closely associated with disease development of rosacea.
Humans ; Polymorphism, Single Nucleotide ; Histocompatibility Antigens Class I/genetics* ; Rosacea/genetics* ; Genetic Predisposition to Disease/genetics* ; Female ; Male ; Adult ; Middle Aged ; Genotype ; Alleles ; Gene Frequency ; Haplotypes ; Case-Control Studies ; Aged ; High-Throughput Nucleotide Sequencing