recent positive selection on genes associated with/linked to male pattern baldness

From the paper (AGA = pattern baldness):

Interestingly, it is the AGA risk haplotype that
shows evidence for positive selection in the European
population. The AGA risk haplotype also carries a derived
non-synonymous allele (57K) in the flanking ectodysplasin
A2 receptor gene (EDA2R). The 57K allele may have been
the target of positive selection in East Asians: it shows
large allele frequency diverences between populations,
lies in a likely functional domain of the
EDA2R protein, and the ancestral allele, 57R, is conserved
from human to rat. Thus, the AGA risk haplotype may have
hitchhiked to high frequency in Europeans as a result of
positive selection on the linked 57K allele in EDA2R