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Am J Neurodegener Dis 2013;2(1):35-39

Original Article
Convenient diagnosis of spinal and bulbar muscular atrophy using a
microchip electrophoresis system

Hirofumi Maruyama, Hiroyuki Morino, Yuishin Izumi, Kouichi Noda, Hideshi Kawakami

Department of Epidemiology, Research Institute for Radiation Biology and Medicine, Hiroshima University, Hiroshima,
Japan; Department of Neurology, Tokushima University Hospital, Tokushima, Japan; Department of Neurology,
Higashihiroshima Medical Center, Higashihiroshima, Japan

Received December 5, 2012; Accepted January 15, 2013; Epub March 8, 2013; Published March 18, 2013

Abstract: Spinal and bulbar muscular atrophy (SBMA) is a slowly progressive motor neuron disease. Lower and
primary sensory neuronopathy is one of the major neuropathological changes that occurs in SBMA. However, many
sings are common to SBMA and amyotrophic lateral sclerosis (ALS), and SBMA patients are sometimes diagnosed
with ALS. Leuprorelin may be used to treat SBMA, but an accurate diagnosis is necessary for treatment and care.
Genetic diagnosis can be performed to detect the expansion of a CAG repeat in the androgen receptor gene in SBMA
patients. To screen for this expansion, we used a microchip electrophoresis system. The discrepancy between the
actual repeat length and that found by the microchip electrophoresis system was roughly dependent on the repeat
length. The mean difference was –6.8 base pairs (bp) in SBMA patients, –0.30 bp in controls. The microchip
electrophoresis results were approximately 2 CAG repeats shorter than the actual repeat length in SBMA patients.
Using this method, we screened our ALS samples (31 were familial, 271 were sporadic): 4 subjects were diagnosed
with SBMA; 2 had familial ALS, and 2 had sporadic ALS (0.7%). The microchip electrophoresis system is semi-
quantitative, convenient and useful for screening a large number of samples. (AJND1212003)

Keywords: Spinal and bulbar muscular atrophy, androgen receptor, CAG repeat, microchip electrophoresis,
amyotrophic lateral sclerosis

Address correspondence to: Dr. Hirofumi Maruyama, 1-2-3 Kasumi, Minami-ku, Hiroshima, Japan, 734-8553. Tel:
+81-82-257-5847; Fax: +81-82-257-5848; E-mail: hmaru@hiroshima-u.ac.jp