Infantile convulsion choreoathetosis syndrome in a Hong Kong Chinese Family

Abstract

Purpose: To describe the clinical features of a Hong Kong Chinese family with infantile convulsion choreoathetosis syndrome (ICCA) and the results of the preliminary genetic workup. Method: Medical records review was performed in our 2 index patients. Direct sequencing of the coding exons of SLC5A11 (Gene ID: 115584 ) was done on one of the index patients (CWP), his mother and normal sister. Results: Patient 1 (CWP) was a one -year old boy who presented to us with recurrent generalized tonic clonic convulsions since 6 months of age. He was treated with low dose valproate and remained seizure free. He had normal development. Patien t 2 (CWH) was a fifteen -year old boy. He had multiple seizures during an episode of viral illness at 11 months old and was then seizure free. Since the age of 10, he started to have paroxysmal kinesigenic dyskinesia (PKD) but was initially thought to have pseudoseizures. Once diagnosed, low-dose carbamazepine induced remission. He had normal intelligence. 4 other family members had infantile convulsions with complete remission after few years of age. They did not have PKD. 2 more had PKD without infantile c convulsion. They were not on treatment. The SLC5A11 gene was reported to be involved in ICCA in families in other populations. Direct sequencing of the 15 coding exons of SLC5A11 gene did not show any coding mutations or splicing junction changes in the affected family members, indicating that this gene may not be involved in this family. Further linkage study is in progress. Conclusion: Early identification of this epilepsy syndrome allows appropriate counseling of the prognosis of the infantile-onset epilepsy, which is usually benign and easy -to-treat. Paroxysmal kinesigenic dyskinesia, being another part of this syndrome might be misinterpreted as epilepsy.