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Two mild cases of Dravet syndrome with truncating mutation of SCN1A
Toru Takaori1, Akira Kumakura1, Atsushi Ishii2
1Department of Pediatrics, Kitano Hospital, The Tazuke Kofukai Medical Institute, Osaka, Japan.
Background:
SCN1A is the gene that codes for the neuronal voltage-gated sodium-channel alpha-subunit 1. It is generally considered that an SCN1A truncating mutation causes the severe phenotype of Dravet syndrome.
Patients:
We describe 11- and 4-year-old male patients presenting with mild Dravet syndrome with a truncating mutation of SCN1A. The former patient showed moderate mental retardation; however, seizure was controlled to almost one incident a year by levetiracetam and topiramate. Carbamazepine was also effective, which is atypical of Dravet syndrome. The latter patient showed a borderline developmental quotient and did not have episodes of afebrile seizure.
Conclusion:
Two patients presented with mild Dravet syndrome, even though they had a truncating mutation of SCN1A. Not all truncating mutations of SCN1A cause the severe phenotype of Dravet syndrome.
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