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.