Comparison of GAD and ICA512/IA-2 antibodies at and after the onset of IDDM.
OBJECTIVE
Longitudinal changes in GAD antibody (Ab) and ICA512/IA-2 (ICA512) Ab were examined in relation to age at the onset of diabetes and autoimmunity against the thyroid gland.


METHODS
GADAb, ICA512Ab, and antithyroid autoantibody were examined at onset in 40 juvenile-onset IDDM patients (17 males, 23 females, age at onset 9.4 +/- 4.1 years, range 1.7-20). To assess the changes in antibody levels, 29 patients were followed up with sequential serum samples for up to 5 years.


RESULTS
At onset, GADAb, ICA512Ab, and antithyroid autoantibody (thyroglobulinAb or thyroid peroxidaseAb) were found in 70, 58, and 25% of the 40 patients, respectively. Prepubertal patients (n = 21) had a significantly higher prevalence and index of ICA512Ab compared with pubertal patients (n = 19) (76 vs. 37%, P = 0.012, and 2.43 +/- 2.36 vs. 0.66 +/- 1.23, P = 0.011), while GADAb was more prevalent in pubertal patients (57 vs. 84%, P = 0.09). A longitudinal analysis of GADAb and ICA512Ab showed that GADAb levels declined more slowly than those of ICA512Ab (P = 0.008). Patients with continuous extremely high levels of GADAb also had high levels of antithyroid autoantibody.


CONCLUSIONS
The measurement of ICA512Ab is useful in prepubertal patients, who often show rapid progression of the disease. The presence of autoimmunity against thyroid gland seems to influence the GADAb level but not the ICA512Ab level.
Yokota
I
I
Department of Pediatrics, School of Medicine, University of Tokushima, Japan. yichiro@clin.med.tokushima-u.ac.jp
Matsuda
J
J
Naito
E
E
Ito
M
M
Shima
K
K
Kuroda
Y
Y
D000293:Adolescent; D000328:Adult; D017668:Age of Onset; D001323:Autoantibodies / Q000097:blood*; D001324:Autoantigens; D002648:Child; D002675:Child, Preschool; D003922:Diabetes Mellitus, Type 1 / Q000097:blood / Q000276:immunology*; D005260:Female; D005968:Glutamate Decarboxylase / Q000276:immunology*; D006801:Humans; D007223:Infant; D007515:Islets of Langerhans / Q000276:immunology; D008137:Longitudinal Studies; D008297:Male; D008565:Membrane Proteins / Q000097:blood*; D054562:Protein Tyrosine Phosphatase, Non-Receptor Type 1; D017027:Protein Tyrosine Phosphatases / Q000097:blood*; D011627:Puberty; D054635:Receptor-Like Protein Tyrosine Phosphatases, Class 8
D001323:Autoantibodies; D001324:Autoantigens; D008565:Membrane Proteins; C516862:PTPRN protein, human; D054562:Protein Tyrosine Phosphatase, Non-Receptor Type 1; D017027:Protein Tyrosine Phosphatases; D054635:Receptor-Like Protein Tyrosine Phosphatases, Class 8; D005968:Glutamate Decarboxylase