Rapid diagnosis of glycine encephalopathy by 13C-glycine breath test.
OBJECTIVE
It is currently problematic to confirm the clinical diagnosis of glycine encephalopathy, requiring either invasive liver biopsy for enzymatic analysis of the glycine cleavage system or exhaustive mutation analysis. Because the glycine cleavage system breaks down glycine generating carbon dioxide, we suppose that the glycine cleavage system activity could be evaluated in vivo by measuring exhaled (13)CO(2) after administration of [1-(13)C]glycine.


METHODS
The [1-(13)C]glycine breath test was performed in 10 control subjects and 5 glycine encephalopathy patients with GLDC mutation, including 1 patient with mild glycine encephalopathy.


RESULTS
All the patients showed lower (13)CO(2) excretion than any control subject.


CONCLUSIONS
Not only typical GE but also atypical GE can be reliably diagnosed by the (13)C-glycine breath test. Because it is rapid, non-invasive, and requires little expertise, the breath test could be useful as a standard test for diagnosing GE.
Kure
Shigeo
S
Department of Medical Genetics, Tohoku University School of Medicine, Sendai, Japan. skure@mail.tains.tohoku.ac.jp
Korman
Stanley H
SH
Kanno
Junko
J
Narisawa
Ayumi
A
Kubota
Mitsuru
M
Takayanagi
Toshimitsu
T
Takayanagi
Masaki
M
Saito
Takashi
T
Matsui
Akira
A
Kamada
Fumiaki
F
Aoki
Yoko
Y
Ohura
Toshihiro
T
Matsubara
Yoichi
Y
D000293:Adolescent; D001925:Brain Damage, Chronic / Q000175:diagnosis* / Q000235:genetics; D001944:Breath Tests; D002245:Carbon Dioxide / Q000378:metabolism; D002247:Carbon Isotopes; D002648:Child; D002675:Child, Preschool; D005260:Female; D005998:Glycine / Q000032:analysis* / Q000378:metabolism / Q000502:physiology*; D006801:Humans; D006943:Hyperglycemia / Q000175:diagnosis* / Q000235:genetics; D007223:Infant; D008297:Male; D010084:Oxidation-Reduction; D015203:Reproducibility of Results
D002247:Carbon Isotopes; D002245:Carbon Dioxide; D005998:Glycine