Glutamic Acid Decarboxylase (GAD65) antibodies may be asymptomatic or associated with a variety of neurological manifestations. It is frequently associated with Type 1 diabetes.
The main objective is to determine the clinical characteristics and treatments used for patients with GAD-65 antibodies.
This was an observational, retrospective, single-center study enrolling all patients found to be positive for GAD65 antibodies between January 2010 and December 2019. To select for cases thought to have neurologic manifestations of GAD65 autoantibodies, we further selected for subjects who were evaluated and assessed by the neurology service.
1015 patients tested positive for GAD65 autoantibodies, but only 123 (12.1%) patients were evaluated by the neurology service. Among the subset evaluated by Neurology, the mean age was 47.1 (±20.8) and 67 (54.5%) were female. Diabetes mellitus (DM) was seen in 60 (48.8%) of the cases. The most common neurological manifestation was as follows: seizure 32 (26%), stiff-person syndrome 30 (24.4%), encephalitis 17 (13.8%), ataxia 16 (13%) and nystagmus 6 (4.9%). Thirty nine (31.7%) patients were diagnosed with peripheral neuropathy, which was likely secondary to DM in most cases. Seizure and stiffness were observed more frequently in females, although this was not a statistically significant difference.
Abnormal MRI brain was seen in 60 (48.8%) of the cases. Patient were treated with: intravenous steroid 45 (36.6%), oral steroid 59 (48%), intravenous immunoglobulin 58 (47.2%), plasmapheresis 14 (11.4%), rituximab 25 (20.3%), azathioprine 15 (12.2%), mycophenolate mofetil 12 (9.8%) and cyclophosphamide 6 (4.9%).
At least one tenth of GAD-65 antibody positive cases needed a neurological evaluation. The most common clinical presentations in our cohort were seizures and stiff-person syndrome.