Germline mosaicism in a family with MBD5 haploinsufficiency

Haploinsufficiency of the methyl-CpG-binding domain protein 5 (MBD5) gene causes a neurodevelopmental disorder that includes intellectual disability, developmental delay, speech impairment, seizures, sleep disturbances, and behavioral difficulties. Microdeletion of 2q23.1 is the most common cause of haploinsufficiency, although MBD5 haploinsufficiency may also cause this genetic disorder. We report a family harboring a heterozygous loss-of-function variant in MBD5 (NM_018328.5:c.728delC; p.Pro243Hisfs*26), which includes three affected siblings with varying phenotypic features. Both parents were phenotypically normal but deep coverage sequencing of the parents showed germline mosaicism in the mother. </p

De-novo mutations in patients with chronic ultra-refractory epilepsy with onset after age five years

We set out to investigate whether a de-novo paradigm could explain genetic causes of chronic ultra-refractory epilepsy, with onset later than the typical age for the epileptic encephalopathies. We performed exome sequencing on nine adult patients with MRI-negative epilepsy and no preceding intellectual disability. All had an onset of seizures after five years old and had chronic ultra-refractory epilepsy defined here as having failed more than six anti-epileptic drugs and currently experiencing ≥4 disabling seizures per month. Parents were sequenced to identify de-novo mutations and these were assessed for likelihood of pathogenicity based on the American College of Medical Genetics and Genomics (ACMG) criteria. We confirmed the presence of functional and predicted-damaging de-novo mutations in 3/9 patients. One of these pathogenic de-novo mutations, in DNM1L, was previously reported in a patient with severe epilepsy and chronic pharmacoresistance adding to the evidence for DNM1L as an epilepsy gene. Exome sequencing is a successful strategy for identifying de-novo mutations in paediatric epileptic encephalopathies and rare neurological disorders. Our study demonstrates the potential benefit of considering ultra-refractory epilepsy patients with later onset for genetic testing. Identifying genetic mutations underpinning severe epilepsy of unknown aetiology may provide new insight into the underlying biology and offers the potential for therapeutic intervention in the form of precision medicine in older patients

Vagus nerve stimulation in refractory idiopathic generalised epilepsy: an Irish retrospective observational study

Objective: Refractory idiopathic generalised epilepsy (IGE; also known as genetic generalised epilepsy) is a clinical challenge due to limited available therapeutic options. While vagus nerve stimulation (VNS) is approved as an adjunctive treatment for drug-resistant focal epilepsy, there is limited evidence supporting its efficacy for refractory IGE. Methods: We conducted a single-centre retrospective analysis of adult IGE patients treated with VNS between January 2003 and January 2022. We analysed the efficacy, safety, tolerability, stimulation parameters and potential clinical features of VNS response in this IGE cohort. Results: Twenty-three IGE patients were implanted with VNS between January 2003 and January 2022. Twenty-two patients (95.65%) were female. The median baseline seizure frequency was 30 per month (interquartile range [IQR]= 140), including generalised tonic-clonic seizures (GTCS), absences, myoclonus, and eyelid myoclonia with/without absences. The median number of baseline anti-seizure medications (ASM) was three (IQR= 2). Patients had previously failed a median of six ASM (IQR= 5). At the end of the study period, VNS therapy remained active in 17 patients (73.9%). amongst patients who continued VNS, thirteen (56.5% of the overall cohort) were considered responders (≥50% seizure frequency reduction). Amongst the clinical variables analysed, only psychiatric comorbidity correlated with poorer seizure outcomes, but was non-significant after applying the Bonferroni correction. Although 16 patients reported side-effects, none resulted in the discontinuation of VNS therapy. Significance: Over half of the patients with refractory IGE experienced a positive response to VNS therapy. VNS represents a viable treatment option for patients with refractory IGE, particularly for females, when other therapeutic options have been exhausted.</p