Study on Tolerability of Levodopa/Carbidopa in Children With Angelman Syndrome

This study is designed to determine the highest dose of levodopa/carbidopa that can be tolerated without any serious side effects by children with Angelman syndrome. It has been hypothesized that levodopa may lead to an improvement in the neurodevelopment and abnormal movements (e.g. tremors) in children with Angelman syndrome. Data from this study will be used to design a phase II trial to determine the efficacy of levodopa in treating children with Angelman syndrome.

Levodopa is a prodrug that "delivers" dopamine to the brain. It is usually given with carbidopa, a peripheral decarboxylase inhibitor, to increase the bioavailability of levodopa. Animal studies have suggested that levodopa can reverse the excess phosphorylation of some enzymes involved in synaptic and neuronal function, including calcium/calmodulin-dependent kinase type 2 (CaMKII). Recently, it was shown that excess phosphorylation of CaMKII may be responsible for some of the neurological deficits seen in Angelman syndrome. Therefore, it is hypothesized that levodopa may lead to an improvement in the neurodevelopment and abnormal movements (e.g. tremors) in children with Angelman syndrome. Although many children have used levodopa for a variety of medical conditions over the last 30 years, it has not been approved by the Food and Drug Administration (FDA) for use in children, and it has not been formally studied in children with Angelman syndrome, so we do not know what dose of levodopa is most appropriate for children with Angelman syndrome. Therefore, the purpose of this study is to find out the highest dose of levodopa that children with Angelman syndrome can tolerate without any serious side effects. Once we know the dose of levodopa that can be tolerated by children with Angelman syndrome, we will conduct a larger follow-up study to find out whether levodopa will lead to an improvement in their development and tremor.