Chewing induced reflex seizures ("eating epilepsy") and eye closure sensitivity as a common feature in pediatric patients with SYNGAP1 mutations: Review of literature and report of 8 cases.

PURPOSE: Heterozygous SYNGAP1 gene mutations have been associated with several forms of idiopathic generalized epilepsy, autism spectrum disorders and delay of psychomotor development. We report eight patients with a SYNGAP1 mutation and chewing/eating induced reflex seizures as new phenotype and compare them to other patients with eating epilepsy and genetic mutations. METHODS: Presentation of clinical and anamnestic features and retrospective analysis of Video-EEG data of a 4 year old index patient with SYNGAP1 mutation and chewing /eating induced seizures. Clinical and anamnestic features and home videos of seven additional patients (4 female; age: 4-14 years) with SYNGAP1 mutation and eating induced reflex seizures were compared. RESULTS: All reflex seizures of the index patient showed similar focal EEG pattern with 1-5 seconds high amplitude, irregular 3/sec spike-wave complexes with initiation from left temporo-occipital, right temporo-occipital or bi- occipital / temporo-occipital regions. Eyelid myoclonia, the most common seizure type in all 8 patients, were typically initiated by eating or other simple orofacial stimuli. In the index patient eye closure preceded eating induced-eyelid myoclonia in 30/38 seizures. CONCLUSION: The main clinical features of our patient (i.e. intellectual disability, epilepsy, autistic features) are compatible with previous reports on patients with SYNGAP1 mutations. This is the first complete description of eating induced seizures in association with SYNGAP1 mutations. Whether eye closure sensitivity (ECS) represents an independent reflex epileptic trait, as seen in other patients with idiopathic "generalized" epilepsies (IGE), or eye closure is part of a complex trigger mechanism in SYNGAP1 patients' remains to be elucidated.

A new p.(Ile66Serfs*93) IGF2 variant is associated with pre- and postnatal growth retardation.

Objective The IGF/IGF1R axis is involved in the regulation of human growth. Both IGF1 and IGF2 can bind to the IGF1R in order to promote growth via the downstream PI3K/AKT pathway. Pathogenic mutations in IGF1 and IGF1R determine intrauterine growth restriction and affect postnatal body growth. However, to date, there are only few reports of pathogenic IGF2 mutations causing severe prenatal, as well as postnatal growth retardation. Results Here we describe a de novo c.195delC IGF2 variant (NM_000612, p.(Ile66Serfs*93)) in a 4-year-old patient with severe pre- and post-natal growth retardation in combination with dystrophy, facial dimorphism, finger deformities, as well as a patent ductus. Cloning and sequencing of a long-range PCR product harboring the deletion and a SNP informative site chr11:2153634 (rs680, NC_000011.9:g.2153634T>C) demonstrated that the variant resided on the paternal allele. This finding is consistent with the known maternal imprinting of IGF2. 3D protein structure prediction and overexpression studies demonstrated that the p.(Ile66Serfs*93) IGF2 gene variation resulted in an altered protein structure that impaired ligand/receptor binding and thus prevents IGF1R activation. Conclusion The severity of the phenotype in combination with the dominant mode of transmission provides further evidence for the involvement of IGF2 in growth disorders.