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Sodium Channel Gene Mutations in Children with GEFS+ and Dravet Syndrome: A Cross Sectional Study
Insights
Dravet syndrome and GEFS+ share genetic links, with SCN1A mutations being key indicators. Early normal development, seizure onset before age one, and later psychomotor issues strongly suggest SCN1A mutations in these epilepsy syndromes.
Area of Science:
- Pediatric Neurology
- Clinical Genetics
- Epileptology
Background:
- Dravet syndrome, or severe myoclonic epilepsy of infancy (SMEI), is a severe epileptic encephalopathy starting in infancy.
- It is characterized by febrile seizures, intractable epilepsy, developmental delays, and ataxia.
- Dravet syndrome and generalized epilepsy with febrile seizure plus (GEFS+) share clinical and genetic similarities, suggesting they may represent a spectrum of the same disorder.
Purpose of the Study:
- To compare clinical features and genetic findings in patients diagnosed with Dravet syndrome or GEFS+.
- To identify key diagnostic criteria for SCN1A mutations in these epilepsy syndromes.
Main Methods:
- A study of 35 patients (May 2008-August 2012) meeting Dravet syndrome criteria at Mofid Children Hospital.
- Clinical features and genetic findings were compared between Dravet syndrome and GEFS+ patients.
- Genetic testing was performed to detect SCN1A mutations.
Main Results:
- SCN1A mutations were identified in 33.3% of clinically diagnosed Dravet syndrome patients and 15% of GEFS+ patients.
- Key indicators for SCN1A mutations included normal development before seizures, onset before age one, and psychomotor retardation after seizure onset.
- The study analyzed 35 patients (15 female, 20 male) with a mean age of 7.7 years.
Conclusions:
- Normal development prior to seizure onset, seizures beginning before one year of age, and psychomotor retardation after age two are significant indicators of SCN1A mutations.
- These findings support the role of SCN1A mutations in the pathogenesis of Dravet syndrome and GEFS+.
Objective:
Dravet syndrome or severe myoclonic epilepsy of infancy (SMEI) is a baleful epileptic encephalopathy that begins in the first year of life. This syndrome specified by febrile seizures followed by intractable epilepsy, disturbed psychomotor development, and ataxia. Clinical similarities between Dravet syndrome and generalized epilepsy with febrile seizure plus (GEFS+) includes occurrence of febrile seizures and joint molecular genetic etiology. Shared features of these two diseases support the idea that these two disorders represent a severity spectrum of the same illness. Nowadays, more than 60 heterozygous pattern SCN1A mutations, which many are de novo mutations, have been detected in Dravet syndrome.
Materials & Methods:
From May 2008 to August 2012, 35 patients who referred to Pediatric Neurology Clinic of Mofid Children Hospital in Tehran were enrolled in this study. Entrance criterion of this study was having equal or more than four criteria for Dravet syndrome. We compared clinical features and genetic findings of the patients diagnosed as Dravet syndrome or GEFS+.
Results:
35 patients (15 girls and 20 boys) underwent genetic testing. Mean age of them was 7.7 years (a range of 13 months to 15 years). Three criteria that were best evident in SCN1A mutation positive patients are as follows: "Normal development before the onset of seizures, onset of seizure before age of one year, and psychomotor retardation after onset of seizures. Our genetic testing showed that 1 of 3 (33.3%) patients with clinical Dravet syndrome and 3 of 20 (15%) patients that diagnosed as GEFS+, had SCN1A mutation.
Conclusion:
In this study, normal development before seizure onset, seizures beginning before age of one year and psychomotor retardation after age of two years are the most significant criteria in SCN1A mutation positive patients.
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