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Myoclonic encephalopathy and diabetes mellitus in a boy
C Lenti1, E Bognetti, R Bonfanti
1Institute of Neurological and Psychiatric Sciences of Childhood and Adolescence, Milan, Italy.
Insights
A child with diabetes developed dancing eye syndrome due to a common autoimmune disorder targeting glutamic-acid decarboxylase (GAD). Treatment reduced GAD antibodies and neurological symptoms.
Area of Science:
- Pediatric Neurology
- Immunology
- Endocrinology
Background:
- Idiopathic myoclonic encephalopathy, also known as dancing eye syndrome, is a rare neurological disorder.
- Insulin-dependent diabetes mellitus is an autoimmune condition affecting pancreatic beta-cells.
Observation:
- An 18-month-old boy with diabetes developed neurological symptoms including multifocal myoclonus, opsoclonus, ataxia, and behavioral disturbance.
- These symptoms appeared rapidly, within 10-14 days, and other causes like infection or tumors were excluded.
Findings:
- Anti-glutamic-acid decarboxylase (GAD) antibodies were present at diabetes onset and significantly increased with neurological symptoms.
- Corticosteroid treatment led to decreased anti-GAD antibody titers and resolution of neurological disturbances.
Implications:
- This case suggests a potential autoimmune link between diabetes and myoclonic encephalopathy mediated by anti-GAD antibodies.
- Glutamic-acid decarboxylase (GAD) is expressed in both pancreatic beta-cells and cerebellar Purkinje cells, supporting a shared autoimmune target.
- Further research into autoimmune disorders targeting GAD may reveal new therapeutic strategies for both conditions.
Abstract:
We describe an 18-month-old boy with insulin-dependent diabetes mellitus who developed idiopathic myoclonic encephalopathy (dancing eye syndrome) at 26 months of age. The neurological symptomatology (multifocal myoclonus, opsoclonus, ataxia, behavioural disturbance) developed within 10 to 14 days after presentation. Biological, neuroradiological, and scintigraphic examination excluded CNS infectious diseases, intoxication, or tumours. At onset of diabetes mellitus, anti-glutamic-acid decarboxylase (GAD) antibodies were observed, and markedly increased in titre when myoclonic encephalopathy occurred. Corticosteroid treatment resulted in a decrease in anti-GAD autoantibody titres and the disappearance of neurological disturbances. As GAD is expressed both in pancreatic beta-cells and cerebellar Purkinje cells, it is possible that a common autoimmune disorder in this patient may account for both the diabetes and myoclonic encephalopathy.