We describe the clinical, electroencephalography (EEG), and developmental features of a patient with developmental and epileptic encephalopathy due to a homozygous pathogenic variation of mitochondrial glutamate/H+ symporter SLC25A22. Epilepsy began during the first week of life with focal onset seizures. Interictal EEG revealed a suppression-burst pattern with extensive periods of non-activity. The prospective follow-up confirmed developmental encephalopathy as well as ongoing active epilepsy and almost no sign of development at 8 years of age. We confirm in the following paper that SLC25A22 recessive variations may cause a severe developmental and epileptic encephalopathy characterized by a suppression-burst pattern. On the basis of an in-depth literature review, we also provide an overview of this rare genetic cause of neonatal onset epilepsy.

OBJECTIVE: To assess if absence seizures (ASs) occur in patients with myoclonic epilepsy of infancy (MEI).
METHODS: A retrospective chart review was conducted in 37 patients with MEI followed at seven different paediatric epilepsy centres in Italy, between 2002 and 2014. To assess the possible occurrence of pure ASs or absences associated with myoclonias, ASs were defined according to the following criteria: (i) a sudden onset and interruption of ongoing activities; (ii) bilateral polyspikes or spike-and-wave (SW) complexes; spike SW complexes at 2-4Hz; (iii) duration of AS: 3-30seconds.
RESULTS: Thirty-seven MEI patients (25 boys and 12 girls) were identified. Nine patients (24.3%) had a history of simple FS during the first year of life. Ten patients (27%) had a family history of epilepsy, and six patients (16.2%) had a family history of FS. In 7/37 (18.9%) patients, during the occurrence of MSs, a total of nineteen brief ASs were captured by video-EEG recordings. ASs occurred both during a brief cluster of rhythmic MSs than after single myoclonic jerks. The ictal EEG abnormalities observed in patients with ASs were similar to the ictal EEG patterns associated with only myoclonias. No differences in relation to gender, family history, ictal EEG discharge were found between patients with myoclonic seizures with ASs and myoclonias without ASs.
CONCLUSIONS: Absence seizures can occur in approximately 20% of MEI patients and the occurrence of ASs, though not essential to formulate the diagnosis, do not automatically exclude the diagnosis of MEI.