Spectrum of SCN1A mutations in severe myoclonic epilepsy of infancy.

OBJECTIVES: SCN1A mutations were recently reported in several patients with severe myoclonic epilepsy in infancy (SMEI). The authors analyzed SCN1A mutations in 93 patients with SMEI and made genotype-phenotype correlation to clarify the role of this gene in the etiology of SMEI. METHODS: All patients fulfilled the criteria for SMEI. The authors analyzed all patients for SCN1A mutations using denaturing high performance liquid chromatography. If a patient's chromatogram was abnormal, the authors sequenced the gene in the patient and both parents. RESULTS: SCN1A mutations were identified in 33 patients (35%). Most mutations were de novo, but were inherited in three patients. Parents carrying the inherited mutations had either no symptoms or a milder form of epilepsy. A greater frequency of unilateral motor seizures was the only clinical difference between patients with SCN1A mutations and those without. Truncating mutations were more frequently associated with such seizures than were missense mutations. The percentage of cases with family history of epilepsy was significantly higher in patients with SCN1A mutations. CONCLUSIONS: Unilateral motor seizures may be a specific clinical characteristic of SMEI caused by SCN1A mutations. Ten percent of SCN1A mutations are inherited from an asymptomatic or mildly affected parent, suggesting that SMEI is genetically heterogeneous. The increased frequency of familial epilepsy indicates that other genetic factors may contribute to this disorder.

Imaging studies in partial epilepsy in children and adolescents.

We reviewed the results of imaging studies on 111 children and adolescents with partial epilepsy to determine which imaging procedure had the greatest sensitivity and specificity for partial epilepsy in this age range. All cases were classified as idiopathic, lesional, and cryptogenic epilepsy based on the 1989 International League Against Epilepsy Classification. All patients had magnetic resonance imaging (MRI) and 98 also had computed tomography (CT). Thirty patients with negative CT had MRI lesions that were most likely the cause of the epilepsy, and the initial diagnosis of cryptogenic partial epilepsy was changed to lesional partial epilepsy. We concluded that CT use is unwarrantedly common. MRI should be considered the procedure of first choice. CT has a complementary role, and functional neuroimaging should be encouraged.

Progressive myoclonic encephalopathy in X-linked hypogamma-globulinemia. Case report, review of the literature and its relationship with progressive encephalopathy in children with A.I.D.S.

A 7-year-old boy suffering from X-linked hypogammaglobulinemia and progressive myoclonic encephalopathy is reported. The onset of neurological disturbances is at four years of age with ataxic gait and myoclonic jerks. The EEG shows a progressive slowing of background activity, bilateral diffuse and repetitive, pseudoperiodic, high amplitude slow waves, myoclonic jerks polygraphically documented. The CT-scan shows generalized cerebral atrophy, white matter hypodensity--principally in the frontal regions -, multiple nodular calcifications, also in the basal ganglia. Two years after the onset of neurological signs, the boy is completely bedridden, spastic, dement and blind; the myoclonic jerks persist. Finally the relationship is discussed with both the previously reported patients with the same affection, and with similar progressive encephalopathy in children suffering from A.I.D.S.