Patients with Dravet's syndrome and SCN1A-mutation with a benign course of illness – A case report with 6 patients

Question: Are there patients with a SCN1A mutation with a rather benign course of the illness? How is the mental development of these patients? Is there a correlation between genotype and phenotype in these patients?

Methods: Retrospective data analysis.

Results: We examined 6 patients mit SCN1A- mutation who showed the typical seizures of Dravet's syndrome. The age range of the patients was from 5 to 19 years.

	Pat. 1	Pat. 2	Pat. 3	Pat. 4	Pat. 5	Pat. 6
GTCS	+	+	+	+	+	+
Hemi- GTCS	+	+	+	+	+
Clonic seizures	+			+
Atypical absences	+	+		+
Myoclonus	+	+		+	+	+
Versive seizures	+
Psychomotor seizures	+

Except for one patient, all patient had their first seizure during the first year of life. Actually three of the patients are seizure- free, the others have rare seizures, 2–4 seizures/year. Two patients suffer from mild ataxia, one patient shows a clinically significant ataxia, the others show a normal neurological examination. The mental development is very variable and ranges from normal intelligence to severe mental retardation. There is no correlation between the frequency of seizures and the cognitive abilities of the patients. The examined mutations are strewn all over the SCN1A- gene, there is no correlation with a distinct mutation.

Conclusion:

• Patients with a SCN1A mutation treated with antiepileptic drugs may have a rather benign course of epilepsy with a low seizure frequency.

• The cognitive development of patients with SCN1A mutation shows a broad range from normal intelligence to mental retardation.

• In the group of patients with mild course of Dravet's syndrome examined by us was no specific SCN1A mutation in the sense of a genotype- phenotype correlation.