Background

RTF1-congenital disorder of glycosylation (CDG) syndrome is a very rare subtype of CDG syndrome (6 cases reported so far) associating early onset epilepsy, severe developmental delay and deafness. We aimed here at better characterize the electro-clinical presentation in reporting 2 new cases.

Cases report

Girl, born at term with irritability and axial hypotonia. Seizures appeared at 3 months. Video-EEG showed a suppression-burst pattern during slow sleep, and tonic seizures were recorded when awake. Auditory evoked potentials were absent and sialotransferrine electrophoresis suggested CDG-Ix. Seizures resisted to valproate but were controlled by vigabatrin. Direct sequencing of the RFT1 gene showed a homozygote mutation (p.K152E; c.454A>G).

Boy, born at term with irritability and axial hypotonia. Seizures appeared on day 2 of life. Video-EEG showed a suppression-burst pattern in slow sleep with high amplitude generalized spikes and sharp slow waves and both tonic and myoclonic seizures. At 3 months, partial seizures followed by clusters of spasms were recorded. After failure of several drugs, vigabatrin add-on led to an impressive decrease of seizure frequency. Auditory evoked potentials were absent and sialotransferrine electrophoresis was normal. DNA analysis showed that patient was heterozygous compound for RFT1 gene (c.1325G>A (p.R442Q) and c.110G>T (p.R37L)).

Conclusions

RFT1-CDG syndrome should be considered in the differential diagnosis of early epileptic encephalopathy with suppression burst even in the presence of a normal sialotransferrine electrophoresis. Other clues for diagnosis are congenital severe hypotonia and deafness.   Vigabatrin should be used to treat seizures in this disease.