Long-term adverse symptoms of men who used oral finasteride against androgenic alopecia have been recently described as post-finasteride syndrome (PFS). Aim: To determine whether (CAG)n-rs4045402 and (GGN)n-rs3138869 polymorphisms in the androgen receptor (AR) gene are implicated in PFS. Conclusion: This study showed that short and/or long (CAG)n and (GGN)n repeats had different frequencies according to symptoms reported by patients with PFS, likely reflecting the vast array of genes modulated by the AR [and] a U-curvilinear profile of (CAG)n repeats for skin dryness symptoms, where the two extremes exhibited a worse condition than medium repeats.
—Androgen Receptor (AR) Gene (CAG)n and (GGN)n Length Polymorphisms and Symptoms in Young Males With Long-Lasting Adverse Effects After Finasteride Use Against Androgenic Alopecia: Journal of Sexual Medicine, November 2016