Evaluation of SLC20A2 mutations that cause idiopathic basal ganglia calcification in Japan.
OBJECTIVE
To investigate the clinical, genetic, and neuroradiologic presentations of idiopathic basal ganglia calcification (IBGC) in a nationwide study in Japan.


METHODS
We documented clinical and neuroimaging data of a total of 69 subjects including 23 subjects from 10 families and 46 subjects in sporadic cases of IBGC in Japan. Mutational analysis of SLC20A2 was performed.


RESULTS
Six new mutations in SLC20A2 were found in patients with IBGC: 4 missense mutations, 1 nonsense mutation, and 1 frameshift mutation. Four of them were familial cases and 2 were sporadic cases in our survey. The frequency of families with mutations in SLC20A2 in Japan was 50%, which was as high as in a previous report on other regions. The clinical features varied widely among the patients with SLC20A2 mutations. However, 2 distinct families have the same mutation of S637R in SLC20A2 and they have similar characteristics in the clinical course, symptoms, neurologic findings, and neuroimaging. In our study, all the patients with SLC20A2 mutations showed calcification. In familial cases, there were symptomatic and asymptomatic patients in the same family.


CONCLUSIONS
SLC20A2 mutations are a major cause of familial IBGC in Japan. The members in the families with the same mutation had similar patterns of calcification in the brain and the affected members showed similar clinical manifestations.
From the Laboratory of Medical Therapeutics and Molecular Therapeutics (Y.M., M. Takagi, Y.H., M.K., I.H.), Gifu Pharmaceutical University, Gifu; Department of Neurology (M. Tanaka, H. I., J.M., S. Tsuji), The University of Tokyo; Department of Neurology (N.A., G.S.), Nagoya University; Department of Neuropsychiatry (S.K.), Sapporo Medical University, Sapporo; Department of Neurology (Y.Y., S. Takashima, K.T.), Toyama University Hospital, Toyama; Department of Neurology (T.T.), Kagawa University Hospital, Kagawa; Department of Neurology (H.H,S.M.), Tokyo Metropolitan Institute of Gerontology, Tokyo; Department of Neurology and Geriatrics (M.Y., Y.H., T.I.), and Division of Genomic Research, Life Science Research Center (N.S.), Gifu University, Gifu, Japan.
Megumi
M
Yamada
Masaki
M
Tanaka
Mari
M
Takagi
Seiju
S
Kobayashi
Yoshiharu
Y
Taguchi
Shutaro
S
Takashima
Kortaro
K
Tanaka
Tetsuo
T
Touge
Hiroyuki
H
Hatsuta
Shigeo
S
Murayama
Yuichi
Y
Hayashi
Masayuki
M
Kaneko
Hiroyuki
H
Ishiura
Jun
J
Mitsui
Naoki
N
Atsuta
Gen
G
Sobue
Nobuyuki
N
Shimozawa
Takashi
T
Inuzuka
Shoji
S
Tsuji
Isao
I
Hozumi
D000328:Adult; D000368:Aged; D001480:Basal Ganglia Diseases / Q000235:genetics*; D001921:Brain / Q000473:pathology*; D002114:Calcinosis / Q000235:genetics*; D004252:DNA Mutational Analysis / Q000379:methods; D005260:Female; D008040:Genetic Linkage / Q000235:genetics; D020022:Genetic Predisposition to Disease; D006801:Humans; D007564:Japan; D008297:Male; D008875:Middle Aged; D009154:Mutation / Q000235:genetics*; D019636:Neurodegenerative Diseases / Q000235:genetics*; D010375:Pedigree; D050611:Sodium-Phosphate Cotransporter Proteins, Type III / Q000235:genetics*; D055815:Young Adult
C493589:SLC20A2 protein, human; D050611:Sodium-Phosphate Cotransporter Proteins, Type III