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Nagaoki Wakisaka, Yuh-ichi Taira, Masahiro Ishikawa, Kazuhiro Kobayashi, Yoshio Nakamizo, Masashi Uwabu, Takanori Hama, and Masaya Kawakami (NPO Future Medical Laboratory, Tokyo, Japan)
Male pattern baldness (MPB) is a common heritable hair loss in scalp area. Although it is polygenic, most of patients have androgen-dependent trait. Expression of AR gene is increased in bald scalp. Association of polymorphism in the first exon of androgen receptor (AR) gene with MPB has been demonstrated by some authors (Sawaya and Salita, 1998; Ellis et al., 2001). MPB patients have lower number of CAG and GGC triplet repeats in this gene that results in increased expression of AR gene. Therefore, MPB caused by hyper-function of AR may be diagnosed by determination of the AR gene polymorphism. It may help the drug choice for these patients.
We determined CAG and GGC triplets and StuI restriction site in the first exon of AR gene of 233 young (16-29 y) and 490 older MPB patients (30-62 y) and of 54 non-bald men (44-72 y). In Caucasian population, frequency of StuI restriction site (AGGCCT) has been found to be higher in bald (94%) than in normal men (77%). However, not only bald but also normal Japanese we examined (total n=324) had StuI site. Number of the triplet repeats was plotted against symptoms expressed as Hamilton-Norwood typing. There was a broad correlation between these variables. Most cases, which fall within the standard deviation, may be caused by hyper-function of AR. On the other hand, certain cases, which fall in area far from the mean, are thought to be caused by non-androgenic mechanism. Statistic analysis of correlation between the triplet repeats and drug effect on these cases is in progress.
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