Impaired glucose-1,6-biphosphate production due to bi-allelic PGM2L1 mutations is associated with a neurodevelopmental disorder.

We describe a genetic syndrome due to PGM2L1 deficiency. PGM2 and PGM2L1 make hexose-bisphosphates, like glucose-1,6-bisphosphate, which are indispensable cofactors for sugar phosphomutases. These enzymes form the hexose-1-phosphates crucial for NDP-sugars synthesis and ensuing glycosylation reactions. While PGM2 has a wide tissue distribution, PGM2L1 is highly expressed in the brain, accounting for the elevated concentrations of glucose-1,6-bisphosphate found there. Four individuals (three females and one male aged between 2 and 7.5 years) with bi-allelic inactivating mutations of PGM2L1 were identified by exome sequencing. All four had severe developmental and speech delay, dysmorphic facial features, ear anomalies, high arched palate, strabismus, hypotonia, and keratosis pilaris. Early obesity and seizures were present in three individuals. Analysis of the children's fibroblasts showed that glucose-1,6-bisphosphate and other sugar bisphosphates were markedly reduced but still present at concentrations able to stimulate phosphomutases maximally. Hence, the concentrations of NDP-sugars and glycosylation of the heavily glycosylated protein LAMP2 were normal. Consistent with this, serum transferrin was normally glycosylated in affected individuals. PGM2L1 deficiency does not appear to be a glycosylation defect, but the clinical features observed in this neurodevelopmental disorder point toward an important but still unknown role of glucose-1,6-bisphosphate or other sugar bisphosphates in brain metabolism.

Bi-allelic loss-of-function variants in BCAS3 cause a syndromic neurodevelopmental disorder.

BCAS3 microtubule-associated cell migration factor (BCAS3) is a large, highly conserved cytoskeletal protein previously proposed to be critical in angiogenesis and implicated in human embryogenesis and tumorigenesis. Here, we established BCAS3 loss-of-function variants as causative for a neurodevelopmental disorder. We report 15 individuals from eight unrelated families with germline bi-allelic loss-of-function variants in BCAS3. All probands share a global developmental delay accompanied by pyramidal tract involvement, microcephaly, short stature, strabismus, dysmorphic facial features, and seizures. The human phenotype is less severe compared with the Bcas3 knockout mouse model and cannot be explained by angiogenic defects alone. Consistent with being loss-of-function alleles, we observed absence of BCAS3 in probands' primary fibroblasts. By comparing the transcriptomic and proteomic data based on probands' fibroblasts with those of the knockout mouse model, we identified similar dysregulated pathways resulting from over-representation analysis, while the dysregulation of some proposed key interactors could not be confirmed. Together with the results from a tissue-specific Drosophila loss-of-function model, we demonstrate a vital role for BCAS3 in neural tissue development.

Effectiveness and tolerability of perampanel in children and adolescents with refractory epilepsies: first experiences.

OBJECTIVE: This article aims to report the first clinical experiences concerning effectiveness and tolerability of perampanel (PER) in a pediatric population with refractory epilepsies. PATIENTS AND METHODS: This nonsponsored, observational, retrospective survey was conducted through collaboration with multiple centers in Europe. The clinical course of the first pediatric patients treated in these centers with PER was documented with the help of a questionnaire completed by the treating physicians. Effectiveness and adverse effects were evaluated. The study population consisted of 58 patients (mean age, 10.5 years; range, 2-17 years), suffering from various refractory epilepsies, classified as focal epilepsy (n = 36), unclassified generalized epilepsy (n = 12), Lennox-Gastaut syndrome (n = 5), West syndrome (n = 3), and Dravet syndrome (n = 2). RESULTS: The response rate (≥ 50% seizure reduction) after the first 3 months of therapy was 31% (18/58 patients) in total. Complete seizure control was achieved in five patients (9% overall). Aggravation of seizures occurred in five cases (9%). The most frequently occurring adverse effects were reduced vigilance or fatigue (n = 16) and behavioral changes (n = 14). DISCUSSION: PER seems to be effective also in children and adolescents with pharmaco-refractory epilepsies. Tolerability was acceptable.

Clinical Effectiveness of Newborn Screening for Spinal Muscular Atrophy: A Nonrandomized Controlled Trial.

Importance: There is increasing evidence that early diagnosis and treatment are key for outcomes in infants with spinal muscular atrophy (SMA), and newborn screening programs have been implemented to detect the disease before onset of symptoms. However, data from controlled studies that reliably confirm the benefits of newborn screening are lacking. Objective: To compare data obtained on patients with SMA diagnosed through newborn screening and those diagnosed after clinical symptom onset. Design, Setting, and Participants: This nonrandomized controlled trial used data from the SMARTCARE registry to evaluate all children born between January 2018 and September 2021 with genetically confirmed SMA and up to 3 SMN2 copies. The registry includes data from 70 participating centers in Germany, Austria, and Switzerland. Data analysis was performed in February 2023 so that all patients had a minimal follow-up of 18 months. Exposure: Patients born in 2 federal states in Germany underwent screening in a newborn screening pilot project. All other patients were diagnosed after clinical symptom onset. All patients received standard care within the same health care system. Main Outcomes: The primary end point was the achievement of motor milestones. Results: A total of 234 children (123 [52.6%] female) were identified who met inclusion criteria and were included in the analysis: 44 (18.8%) in the newborn screening cohort and 190 children (81.2%) in the clinical symptom onset cohort. The mean (SD) age at start of treatment with 1 of the approved disease-modifying drugs was 1.3 (2.2) months in the newborn screening cohort and 10.7 (9.1) months in the clinical symptom onset cohort. In the newborn screening cohort, 40 of 44 children (90.9%) gained the ability to sit independently vs 141 of 190 (74.2%) in the clinical symptom onset cohort. For independent ambulation, the ratio was 28 of 40 (63.6%) vs 28 of 190 (14.7%). Conclusions and Relevance: This nonrandomized controlled trial demonstrated effectiveness of newborn screening for infants with SMA in the real-world setting. Functional outcomes and thus the response to treatment were significantly better in the newborn screening cohort compared to the unscreened clinical symptom onset group. Trial Registration: German Clinical Trials Register: DRKS00012699.

Atypical Clinical Presentations of TAZ Mutations: An Underdiagnosed Cause of Growth Retardation?

Barth syndrome is known as a highly recognizable X-linked disorder typically presenting with the three hallmarks: (left ventricular non-compaction) cardiomyopathy, neutropenia, and 3-methylglutaconic aciduria. Furthermore, growth retardation, mild skeletal myopathy, and specific facial features as well as mitochondrial dysfunction in muscle are frequently seen. Underlying mutations are found in TAZ and lead to defective cardiolipin remodeling.Here, we report atypical clinical manifestations of TAZ mutations in two male patients initially presenting with growth retardation and very mild skeletal myopathy. As other phenotypic hallmarks were missing, Barth syndrome had not been suspected in these patients. One of them has been incidentally diagnosed in the frame of an in-depth cardiolipin research analysis, while the underlying genetic defect was unexpectedly identified in the second one by exome sequencing. CONCLUSION: These cases underline that TAZ mutations might well be an underdiagnosed cause of skeletal myopathy and growth retardation and do not necessarily manifest with the full clinical picture of Barth syndrome.