Our patients had epilepsy onset in infancy as part of a severe disease affecting the brain that led to death in childhood. We found the underlying mutation. Previously two epilepsy families were described with defects in the same gene. The Italian patients had normal neurological and mental development whereas the Arab patients had moderate intellectual disability. Except for the same form of epilepsy that began in infancy, the diseases in the three families seemed different, likely due to different mutation severity, in spite of the fact that the mutation in our patients does not affect two of the three proteins encoded by the gene whereas the other mutations affect all. (By Dr. Asli Tolun, http://jmg.bmj.com/content/50/3/199 )