Introduction: Finasteride, a type II 5-alpha reductase inhibitor, has demonstrated a good safety and efficacy profile in the treatment of male androgenetic alopecia (AGA). However, the use of finasteride for the treatment of female AGA in women remains limited due to poor efficacy. While clinical studies have failed to demonstrate the efficacy of finasteride for treating female AGA, some case reports describe a marked response to finasteride in treating female AGA. The aim of our study was to demonstrate that epigenetic markers associated with the X-chromosome can identify women that benefit from finasteride treatment for AGA.
Methods: 18 female patients were randomized to receive finasteride (1mg/daily) or placebo treatment for 6 months. Hair counts were performed at two separate regions during the beginning and the end of the study. X methylation analysis (XMA) and the CAG-repeat length in the first exon of the Androgen Receptor (AR) gene were determined for each patient.
Results: Patients receiving finasteride with a skewed XMA-AR CAG-repeat length <24 or >=24 had mean improvements in hair counts of 25.2% (SD 11.43%, n=5) versus -3.9% (SD 3.84%, n=2), respectively (p=0.02, two-tailed, unpaired t-test). In addition, the placebo group had a -1.34% (SD 5.45%, n=5) improvement in hair counts (p=0.002 compared to <24 repeat group).
Conclusion: We present, for the first time, evidence that epigenetic markers predict treatment response to finasteride in female AGA. Patients with a skewed XMA-AR <24 CAG-repeat length have a strong likelihood of responding to finasteride for the treatment of female AGA, whereas patients with a skewed XMA-AR CAG-repeat length >=24 have a low likelihood of responding to finasteride.