Twenty-five patients with a diagnosis of Dravet Syndrome (7 males, 18 females; mean age at inclusion: 10.3; median: 9 卤 7; range: 18 months-30 years) were retrospectively studied. A clinical and genetic study focusing on SCN1A was performed, using DHPLC, gene sequencing and MLPA to detect genomic deletions/duplications. A formal cognitive and behavioral assessment was available for all patients.
Analysis revealed SCN1A mutations comprising missense, truncating mutations and genomic deletions/duplications in eighteen patients and no mutation in seven. The phenotype of mutation positive patients was characterized by a higher number of seizures/month in the first year of life, an earlier seizure onset and a higher frequency of episodes of status epilepticus. The cognitive and behavioral profile was slightly worst in mutation positive patients.
These findings confirm that SCN1A gene mutations are strongly associated to a more severe phenotype in patients with Dravet syndrome.