Abstract: 【Abstract】 Objective To investigate the characteristics of serum immunoglobulin G （IgG） N-glycans in male patients with different subtypes and severity grades of androgenetic alopecia （AGA）. Methods A cross-sectional study was conducted on male patients diagnosed with male-pattern hair loss （MPHL） or female-pattern hair loss （FPHL） who attended the Department of Dermatology, Huashan Hospital, Fudan University between June and December 2022. Clinical data were collected, and serum IgG N-glycans were quantitatively analyzed using ultra-performance liquid chromatography （UPLC）. The content of serum IgG N-glycan structures was compared between patients with different AGA subtypes and among patients with different severity grades of MPHL or FPHL, while derived traits were compared between patients with different AGA subtypes. Point-biserial correlation analysis was conducted to assess associations between serum IgG N-glycans and hair loss severity. Results A total of 85 male patients with AGA were included, comprising 44 MPHL patients and 41 FPHL patients. No significant differences were observed between the two subgroups in terms of age, age at onset, or serum levels of testosterone, sex hormone-binding globulin, uric acid, and 25-hydroxyvitamin D （all P > 0.05）. UPLC showed 23 serum IgG glycans and 5 derived glycan traits （afucosylation, fucosylation, bisecting GlcNAc, terminal galactosylation, and terminal sialylation）. Compared with the MPHL patients, the FPHL patients exhibited significantly increased levels of N-glycans GP5, GP11, GP17, and GP20 （all P < 0.05）, significantly elevated levels of afucosylated IgG N-glycans （P = 0.047）, but significantly reduced core fucosylated IgG N-glycans （P = 0.047）. No significant differences in serum IgG N-glycan composition were observed among patients with varying severity grades of MPHL （all P > 0.05）. In the FPHL patients, the levels of N-glycans GP10 （r = 0.32, P = 0.039） and GP22 （r = -0.32, P = 0.045） were significantly positively and negatively correlated with hair loss severity respectively; receiver operating characteristic curve analysis showed that both GP10 and GP22 had moderate diagnostic value for predicting hair loss severity, with the area under the curve values being 0.69 （95% CI: 0.52 - 0.86） and 0.71 （95% CI: 0.55 - 0.86）, respectively. Conclusion Serum IgG N-glycan profiles differed among male patients with different AGA subtypes, and N-glycans GP10 and GP22 may serve as potential biomarkers for early assessment of hair loss severity in male FPHL patients.

Key words: Alopecia, Androgenetic alopecia, Male-pattern hair loss, Female-pattern hair loss, Serum immunoglobulin G, N-glycan, Severity