Expression of sex-determining genes in the scalp of men with androgenetic alopecia

Background: The regulation of the cutaneous steroidogenesis in patients with androgenetic alopecia remains largely unclear. Objective: The purpose of this study was to quantify the expression of the sex-determining genes in different scalp areas. Methods: Paired scalp specimens from frontal and occipital scalp areas of 10 patients were examined by real-time RT-PCR for mRNA expression and of 40 patients (mean age 34.9 years, range 22-58) by Western blotting for protein analysis. Results: The SOX-9 mRNA was most abundant in the skin, while SF-1 mRNA was sparsely detected. The protein levels of DAX-1, SRY and WT-1 were significantly higher in the bald scalp (p = 0.003, 0.004 and 0.03, respectively). Only the SRY expression showed a positive correlation with the baldness severity in Norwood-Hamilton classification (p = 0.024). There was no association between patient's age and the protein levels. Immunostaining of SOX-9 was detected in the outer root sheath keratinocytes of hair follicles but not in the dermal papillae. Conclusion: Further study on a larger population, including normal subjects and female patients, is needed to confirm the pathogenic role of sex-determining genes in androgenetic alopecia.