CDKL5 deficiency disorder: case report of a possible new pathogenic variant

Case presentation: A previously healthy full term 4 month-old boy, presented by 1 months with tonic jerks of the upper limbs and slight behavior arrest. He had no signs of infection and no history of recent vaccination. These jerks became daily, more intense, lateralized and associated with oral automatisms and blinking. They had a very brief duration, mostly 20–30 seconds each. EEG showed bilateral temporo-occipital sharp transients and right temporal slow. Phenobarbital was started with partial seizure control; pyridoxine had no effect. Hence, levetiracetam was initiated. A second EEG by the age of 3 months revealed multifocal epileptiform discharges, as well as seizures characterized by pedaling and swimming movements with parietal origin, mostly on the right hemisphere. By this age, he had predominantly axial hypotonia and lost the ability to fix and follow an object. A whole-exome sequencing test showed a chrX:18.598.499 C>G CDKL5 mutation, known as a variant of uncertain significance (VUS) up to now.