Clinical significance of glutamic acid decarboxylase antibodies in patients with epilepsy.
OBJECTIVE
Glutamic acid decarboxylase antibodies (GADAs) have been detected in patients with epilepsy, but the clinical determinants of epilepsy associated with GADA have not been defined.


METHODS
We analyzed GADA with a radioimmunoassay in sera of 253 well-characterized patients with epilepsy and 200 control subjects. The positive samples were confirmed by immunohistochemistry and western blotting (WB). Sera were screened for other autoantibodies.


RESULTS
GADA were detected in 15 patients (5.9%) and in three control subjects (1.5%) (p = 0.026). Seven patients (2.8%) had high GADA titers [>or=1,000 relative units (RUs)/ml], six of whom had temporal lobe epilepsy (TLE). All three GADA-positive control subjects had low titers. Two of the five patients with high GADA titers and available cerebrospinal fluid (CSF) samples had intrathecal synthesis (IS) of GADA; one patient had CSF oligoclonal bands. The prevalence of increased levels of GADA tended to be higher in patients with TLE than in patients with extra-TLE [odds ratio (OR) 1.32, 95% confidence interval (CI) 0.39-4.42; p = 0.657]. The patients with high GADA titers had significantly higher number of other autoantibodies compared to the patients with low GADA titers (p = 0.001) and the patients with normal GADA (p < 0.001).


CONCLUSIONS
High GADA titers were present in a subgroup of patients; close to 90% had TLE. The immunologic profile of these patients suggests that the most probable origin of their epilepsy is autoimmune. A positive IS of GADA may be a marker of an ongoing immune response that could identify those patients in whom a trial with immunosuppressive therapy might be warranted.
Liimatainen
Suvi
S
Department of Neurology and Rehabilitation, Tampere University Hospital, Tampere, Finland. suvi.liimatainen@fimnet.fi
Peltola
Maria
M
Sabater
Lidia
L
Fallah
Mahdi
M
Kharazmi
Elham
E
Haapala
Anna-Maija
AM
Dastidar
Prasun
P
Knip
Mikael
M
Saiz
Albert
A
Peltola
Jukka
J
D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D000368:Aged; D001323:Autoantibodies / Q000097:blood* / Q000134:cerebrospinal fluid / Q000276:immunology; D001327:Autoimmune Diseases / Q000097:blood / Q000175:diagnosis / Q000276:immunology*; D015153:Blotting, Western; D004827:Epilepsy / Q000097:blood / Q000134:cerebrospinal fluid / Q000276:immunology*; D004833:Epilepsy, Temporal Lobe / Q000097:blood / Q000276:immunology; D005260:Female; D005819:Genetic Markers; D005968:Glutamate Decarboxylase / Q000097:blood / Q000276:immunology*; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D016884:Polyendocrinopathies, Autoimmune / Q000175:diagnosis / Q000276:immunology; D011863:Radioimmunoassay
D001323:Autoantibodies; D005819:Genetic Markers; D005968:Glutamate Decarboxylase