Androgenetic (AGA) and senescent alopecia (SA) are common nonscarring hair loss disorders. The histopathology of both disorders involves follicular downsizing, and yet, they differ in the age of onset, pattern of hair loss, and hormonal involvement. We compared gene expression profiles of scalp biopsies from age-matched men with AGA, SA, and normal controls. Our data suggest that follicular
... [Show full abstract] downsizing in AGA is associated with altered expression of genes required for hair follicle cycling. In stark contrast, the transcriptional profile of SA reveals mitochondrial dysfunction and oxidative stress response, which are characteristic of aging tissues. These marked differences between AGA and SA suggest that they are two distinct disorders that present diverse mechanisms for a final common phenotype of follicular downsizing.
