Purpose: To investigate the clinical features, imaging features, and prognosis of mild encephalitis/encephalopathy with a reversible splenial lesion (MERS) in children Methods: The clinical and imaging data of a cohort of 28 children diagnosed as MERS from January 2019 to October 2020 were retrospectively analyzed Results: Of the 28 patients, 17 were males and 11 were females. The onset age ranged from 8 months to 12 years old, with an average age of 4 years and 2 months. All children developed normally before onset, and three of them had a history of febrile convulsion. More than half of the patients (62.9%) had preceding infections of gastrointestinal tract. All the cases developed seizures, and most (71.4%) had more than one time. Other neurological symptoms included dizziness/headache, consciousness disorder, limb weakness, blurred vision, and dysarthria. Cranial magnetic resonance imaging (MRI) showed lesions in the splenium of the corpus callosum in all, extending to other areas of the corpus callosum, bilateral semi-ovoid center, and adjacent periventricular in two cases. The clinical symptoms were relieved after steroids, intravenous immunogloblin, and symptomatic treatment, without abnormal neurodevelopment during the followed-up (2 months-2 years). Complete resolution of the lesions was observed 8-60 days after the initial MRI examinations Conclusion: MERS in children is related to prodromal infection mostly, with a wide spectrum of neurologic symptoms, characteristic MRI manifestations, and good prognosis. K E Y W O R D Schild, magnetic resonance imaging, mild encephalitis/encephalopathy with a reversible splenial lesion (MRES) INTRODUCTIONMild encephalitis/encephalopathy with a reversible splenial lesion (MERS) is a clinico-radiological syndrome first described by Tada et al.

Defects of WW domain-containing oxidoreductase (WWOX) has been associated with autosomal recessive spinocerebellar ataxia type 12 (SCAR12) and severe early-onset epileptic encephalopathy. The mutations in this gene can lead to global developmental delay, acquired microcephaly, and epilepsy. We report an infant with an autosomal recessive severe early-onset epileptic encephalopathy. Whole exome sequencing analysis was applied to the patient. Novel compound heterozygous mutations in the WWOX gene, c.173-2A > G and c.775 T > C (p.Ser259Pro), were identified. The present study expands our knowledge of WWOX mutations and related phenotypes, and provides new information on the genetic defects associated with this disease for clinical diagnosis.

Background MED13L-related intellectual disability is a new syndrome that is characterized by intellectual disability (ID), motor developmental delay, speech impairment, hypotonia and facial dysmorphism. Both the MED13L haploinsufficiency mutation and missense mutation were reported to be causative. It has also been reported that patients carrying missense mutations have more frequent epilepsy and show a more severe phenotype. Case presentation We report a child with ID, speech impairment, severe motor developmental delay, facial deformity, hypotonia, muscular atrophy, scoliosis, odontoprisis, abnormal electroencephalogram (EEG), and congenital ureteropelvic junction obstruction (UPJO) combined with high ureter attachment. We used whole-exome sequencing (WES) to detect the genetic aberration of the child and found a de novo mutation, c.2605C > T (p.Pro869Ser), in the MED13L gene. Neither of her parents carried the mutation. Additionally, we review the literature and summarize the phenotypes and features of reported missense mutations. After reviewing the literature, approximately 17 missense mutations in 20 patients have been reported thus far. For 18 patients (including our case) whose clinical manifestations were provided, 100% of the patients had ID or developmental delay (DD). A total of 88.9, 83.3 and 66.7% of the patients had speech impairment, delayed milestones and hypotonia, respectively. A total of 83.3% of the patients exhibited craniofacial deformity or other dysmorphic features. Behavioral difficulties and autistic features were observed in 55.6% of the patients. Cardiac anomalies were seen in only 27.8% of the patients. Of these patients, 44.4% had epileptic seizures. Of the 17 mutations, 2 were located in the N-terminal domain, 8 were located in the C-terminal domain, and 1 was located in an α-helical sequence stretch. One of them was located in the MID domain of the MedPIWI module. Conclusions We report a new patient with a reported missense mutation, c.2605C > T (p.Pro869Ser), who exhibited some infrequent manifestations except common phenotypes, which may broaden the known clinical spectrum. Additionally, by reviewing the literature, we also found that patients with missense mutations have a higher incidence of seizures, MRI abnormalities, autistic features and cardiac anomalies. They also have more severe ID and hypotonia. Our case further demonstrates that Pro869Ser is a hotspot mutation of the MED13L gene.

Objective To investigate the clinical and MRI features of myelin oligodendrocyte glycoprotein (MOG) antibody‐positive cerebral cortical encephalitis. Methods To summarize the clinical manifestations, magnetic resonance imaging (MRI) features, and diagnosis and treatment of two children diagnosed with MOG antibody‐positive cortical encephalitis in our hospital, and to analyze all of the literature on MOG antibody‐positive associated cerebral cortical encephalitis published in the last 10 years. Results A total of 24 patients, 20 adults, and 4 children were included. The main symptoms of all observed patients were as follows: seizures 20/24 (83%), headache 18/24 (75%), fever 13/24 (54%), and increased cell number in cerebrospinal fluid 22/24 (92%). The main radiological sign was enhanced FLAIR signal in cortical 24/24 (100%), including enhanced fluid‐attenuated inversion recovery (FLAIR) signal in unilateral cortical 20/24 (83%). Conclusions The clinical manifestations of MOG antibody‐positive cerebral cortical encephalitis are complex and varied, and long‐term follow‐up is needed to clarify the prognosis and recurrence, providing reference for the clinical treatment.

Background With the rapid development of genetic detection technology, especially next‐generation sequencing, identification of the aetiology of unexplained intellectual disabilities accompanied by seizures and other dysmorphic features has become possible. The purpose of our paper is to make a definitive diagnosis of a girl with neonatal hypotonia, severe global developmental delay, seizures and mild facial dysmorphism. Methods The clinical data of the patient were retrospectively studied. Whole‐exome sequencing was performed on a blood sample from the patient. Subsequently, Sanger sequencing was utilized for validation of variants and parental validation. Results The patient had hypotonia since the neonatal period. She showed a significant delay in physical and psychomotor development. She did not have any speech until the age of 2 years and 6 months. She had seizures that were easy to control with levetiracetam. The craniocerebral magnetic resonance imaging (MRI) then showed mild delayed myelination, enlarged bilateral ventricles and widened frontotemporal extracerebral space. Interictal video electroencephalogram (VEEG) was normal. She had esotropia and mild facial abnormalities with a flat nasal bridge and a short nose. She showed no abnormalities in the heart, genitourinary or skeletal systems. Whole‐exome sequencing revealed a novel de novo variant c.5334_5335delAG (p. Arg1778Serfs*11) in the SON gene. Conclusion Our paper reports a novel variant in the SON gene and provides a definitive diagnosis of a female with neonatal hypotonia, severe global developmental delay, seizures and mild facial abnormalities, which are symptoms consistent with Zhu–Tokita–Takenouchi–Kim syndrome (ZTTK syndrome).