Two mild cases of Dravet syndrome with truncating mutation of SCN1A.

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.