Interim analyses of a first-in-human phase 1/2 mRNA trial for propionic acidaemia.

Propionic acidaemia is a rare disorder caused by defects in the propionyl-coenzyme A carboxylase α or ß (PCCA or PCCB) subunits that leads to an accumulation of toxic metabolites and to recurrent, life-threatening metabolic decompensation events. Here we report interim analyses of a first-in-human, phase 1/2, open-label, dose-optimization study and an extension study evaluating the safety and efficacy of mRNA-3927, a dual mRNA therapy encoding PCCA and PCCB. As of 31 May 2023, 16 participants were enrolled across 5 dose cohorts. Twelve of the 16 participants completed the dose-optimization study and enrolled in the extension study. A total of 346 intravenous doses of mRNA-3927 were administered over a total of 15.69 person-years of treatment. No dose-limiting toxicities occurred. Treatment-emergent adverse events were reported in 15 out of the 16 (93.8%) participants. Preliminary analysis suggests an increase in the exposure to mRNA-3927 with dose escalation, and a 70% reduction in the risk of metabolic decompensation events among 8 participants who reported them in the 12-month pretreatment period.

Pathogenic variants in GCSH encoding the moonlighting H-protein cause combined nonketotic hyperglycinemia and lipoate deficiency.

Maintaining protein lipoylation is vital for cell metabolism. The H-protein encoded by GCSH has a dual role in protein lipoylation required for bioenergetic enzymes including pyruvate dehydrogenase and 2-ketoglutarate dehydrogenase, and in the one-carbon metabolism through its involvement in glycine cleavage enzyme system, intersecting two vital roles for cell survival. Here, we report six patients with biallelic pathogenic variants in GCSH and a broad clinical spectrum ranging from neonatal fatal glycine encephalopathy to an attenuated phenotype of developmental delay, behavioral problems, limited epilepsy and variable movement problems. The mutational spectrum includes one insertion c.293-2_293-1insT, one deletion c.122_(228 + 1_229-1) del, one duplication of exons 4 and 5, one nonsense variant p.Gln76*and four missense p.His57Arg, p.Pro115Leu and p.Thr148Pro and the previously described p.Met1?. Via functional studies in patient's fibroblasts, molecular modeling, expression analysis in GCSH knockdown COS7 cells and yeast, and in vitro protein studies, we demonstrate for the first time that most variants identified in our cohort produced a hypomorphic effect on both mitochondrial activities, protein lipoylation and glycine metabolism, causing combined deficiency, whereas some missense variants affect primarily one function only. The clinical features of the patients reflect the impact of the GCSH changes on any of the two functions analyzed. Our analysis illustrates the complex interplay of functional and clinical impact when pathogenic variants affect a multifunctional protein involved in two metabolic pathways and emphasizes the value of the functional assays to select the treatment and investigate new personalized options.

Phosphomannomutase 2 (PMM2) variants leading to hyperinsulinism-polycystic kidney disease are associated with early-onset inflammatory bowel disease and gastric antral foveolar hyperplasia.

Phosphomannomutase 2 (PMM2) deficiency causes Congenital Disorder of Glycosylation (PMM2-CDG), but does not have a recognised association with Inflammatory Bowel Disease (IBD). A distinct clinical syndrome of hyperinsulinism and autosomal recessive polycystic kidney disease (HIPKD) arises in the context of a specific variant in the PMM2 promotor, either in homozygosity, or compound heterozygous with a deleterious PMM2 variant. Here, we describe the development of IBD in three patients with PMM2-HIPKD, with onset of IBD at 0, 6, and 10 years of age. In each case, intestinal inflammation coincided with the unusual finding of gastric antral foveolar hyperplasia. IBD disease was of variable severity at onset but well controlled with conventional and first-line biologic treatment approaches. The organ-level pattern of disease manifestations in PMM2-HIPKD-IBD may reflect a loss of cis-acting regulatory control by hepatocyte nuclear factor 4 alpha (HNF4A). Analysis of published transcriptomic data suggests that IBD most likely arises due to an impact on epithelial cellular function. We identify a specific pattern of variation in PMM2 as a novel association of early-onset IBD with distinctive gastric pathology.

Natural history of epilepsy in argininosuccinic aciduria provides new insights into pathophysiology: A retrospective international study.

OBJECTIVE: Argininosuccinate lyase (ASL) is integral to the urea cycle, which enables nitrogen wasting and biosynthesis of arginine, a precursor of nitric oxide. Inherited ASL deficiency causes argininosuccinic aciduria, the second most common urea cycle defect and an inherited model of systemic nitric oxide deficiency. Patients present with developmental delay, epilepsy, and movement disorder. Here we aim to characterize epilepsy, a common and neurodebilitating comorbidity in argininosuccinic aciduria. METHODS: We conducted a retrospective study in seven tertiary metabolic centers in the UK, Italy, and Canada from 2020 to 2022, to assess the phenotype of epilepsy in argininosuccinic aciduria and correlate it with clinical, biochemical, radiological, and electroencephalographic data. RESULTS: Thirty-seven patients, 1-31 years of age, were included. Twenty-two patients (60%) presented with epilepsy. The median age at epilepsy onset was 24 months. Generalized tonic-clonic and focal seizures were most common in early-onset patients, whereas atypical absences were predominant in late-onset patients. Seventeen patients (77%) required antiseizure medications and six (27%) had pharmacoresistant epilepsy. Patients with epilepsy presented with a severe neurodebilitating disease with higher rates of speech delay (p = .04) and autism spectrum disorders (p = .01) and more frequent arginine supplementation (p = .01) compared to patients without epilepsy. Neonatal seizures were not associated with a higher risk of developing epilepsy. Biomarkers of ureagenesis did not differ between epileptic and non-epileptic patients. Epilepsy onset in early infancy (p = .05) and electroencephalographic background asymmetry (p = .0007) were significant predictors of partially controlled or refractory epilepsy. SIGNIFICANCE: Epilepsy in argininosuccinic aciduria is frequent, polymorphic, and associated with more frequent neurodevelopmental comorbidities. We identified prognostic factors for pharmacoresistance in epilepsy. This study does not support defective ureagenesis as prominent in the pathophysiology of epilepsy but suggests a role of central dopamine deficiency. A role of arginine in epileptogenesis was not supported and warrants further studies to assess the potential arginine neurotoxicity in argininosuccinic aciduria.

Triheptanoin for the treatment of long-chain fatty acid oxidation disorders: Final results of an open-label, long-term extension study.

Long-chain fatty acid oxidation disorders (LC-FAODs) result in life-threatening energy metabolism deficiencies/energy source depletion. Triheptanoin is an odd-carbon, medium chain triglyceride (that is an anaplerotic substrate of calories and fatty acids) for treating pediatric and adult patients with LC-FAODs. Study CL202 (NCT02214160), an open-label extension study of study CL201 (NCT01886378), evaluated the long-term safety/efficacy of triheptanoin in patients with LC-FAODs (N = 94), including cohorts who were triheptanoin naïve (n = 33) or had received triheptanoin in study CL201 (n = 24) or in investigator-sponsored trials/expanded access programs (IST/EAPs; n = 37). Primary endpoint was the annualized rate of LC-FAOD major clinical events (MCEs; rhabdomyolysis, hypoglycemia, cardiomyopathy). Mean ± standard deviation (SD) triheptanoin treatment durations were 27.4 ± 19.9, 46.9 ± 13.6, and 49.6 ± 21.4 months for the triheptanoin-naïve, CL201 rollover, and IST/EAP cohorts, respectively. In the triheptanoin-naïve cohort, median (interquartile range [IQR]) MCE rate significantly decreased from 2.00 (0.67-3.33) events/patient/year pre-triheptanoin to 0.28 (0.00-1.43) events/patient/year with triheptanoin (p = 0.0343), a reduction of 86%. In the CL201 rollover cohort, mean ± SD MCE rate significantly decreased from 1.76 ± 1.64 events/patient/year pre-triheptanoin to 1.00 ± 1.00 events/patient/year with triheptanoin (p = 0.0347), a reduction of 43%. In the IST/EAP cohort, mean ± SD MCE rate was 1.40 ± 2.37 (median [IQR] 0.57 [0.00-1.67]) events/patient/year with triheptanoin. Safety data were consistent with previous observations. Treatment-related treatment-emergent adverse events (TEAEs) occurred in 68.1% of patients and were mostly mild/moderate in severity. Five patients had seven serious treatment-related TEAEs; all resolved. Our results confirm the long-term efficacy of triheptanoin for patients with LC-FAOD.

The incidence of movement disorder increases with age and contrasts with subtle and limited neuroimaging abnormalities in argininosuccinic aciduria.

Argininosuccinate lyase (ASL) is integral to the urea cycle detoxifying neurotoxic ammonia and the nitric oxide (NO) biosynthesis cycle. Inherited ASL deficiency causes argininosuccinic aciduria (ASA), a rare disease with hyperammonemia and NO deficiency. Patients present with developmental delay, epilepsy and movement disorder, associated with NO-mediated downregulation of central catecholamine biosynthesis. A neurodegenerative phenotype has been proposed in ASA. To better characterise this neurodegenerative phenotype in ASA, we conducted a retrospective study in six paediatric and adult metabolic centres in the UK in 2022. We identified 60 patients and specifically looked for neurodegeneration-related symptoms: movement disorder such as ataxia, tremor and dystonia, hypotonia/fatigue and abnormal behaviour. We analysed neuroimaging with diffusion tensor imaging (DTI) magnetic resonance imaging (MRI) in an individual with ASA with movement disorders. We assessed conventional and DTI MRI alongside single photon emission computer tomography (SPECT) with dopamine analogue radionuclide 123 I-ioflupane, in Asl-deficient mice treated by hASL mRNA with normalised ureagenesis. Movement disorders in ASA appear in the second and third decades of life, becoming more prevalent with ageing and independent from the age of onset of hyperammonemia. Neuroimaging can show abnormal DTI features affecting both grey and white matter, preferentially basal ganglia. ASA mouse model with normalised ureagenesis did not recapitulate these DTI findings and showed normal 123 I-ioflupane SPECT and cerebral dopamine metabolomics. Altogether these findings support the pathophysiology of a late-onset movement disorder with cell-autonomous functional central catecholamine dysregulation but without or limited neurodegeneration of dopaminergic neurons, making these symptoms amenable to targeted therapy.

Transplantation in paediatric patients with MMA requires multidisciplinary approach for achievement of good clinical outcomes.

BACKGROUND: As modern medicine is advancing, younger, small, and more complex children are becoming multi-organ transplant candidates. This brings up new challenges in all aspects of their care. METHODS: We describe the first report of a small child receiving a simultaneous liver and kidney transplant and abdominal rectus sheath fascia transplant on the background of Williams syndrome and methylmalonic acidaemia. At the time of transplantation, the child was 3 years old, weighed 14.0 kg, had chronic kidney disease stage V, and had not yet started any other form of kidney replacement therapy. RESULTS: There were many anaesthetic, medical, metabolic, and surgical challenges to consider in this case. A long general anaesthetic time increased the risk of cardiac complications and metabolic decompensation. Additionally, the small size of the patient and the organ size mis-match meant that primary abdominal closure was not possible. The patient's recovery was further complicated by sepsis, transient CNI toxicity, and de novo DSAs. CONCLUSIONS: Through a multidisciplinary approach between 9 specialties in 4 hospitals across England and Wales, and detailed pre-operative planning, a good outcome was achieved for this child. An hour by hour management protocol was drafted to facilitate transplant and included five domains: 1. management at the time of organ offer; 2. before the admission; 3. at admission and before theatre time; 4. intra-operative management; and 5. post-operative management in the first 24 h. Importantly, gaining a clear and in depth understanding of the metabolic state of the patient pre- and peri-operatively was crucial in avoiding metabolic decompensation. Furthermore, an abdominal rectus sheath fascia transplant was required to achieve abdominal closure, which to our knowledge, had never been done before for this indication. Using our experience of this complex case, as well as our experience in transplanting other children with MMA, and through a literature review, we propose a new perioperative management pathway for this complex cohort of transplant recipients.

Evolution of viral variants in remdesivir-treated and untreated SARS-CoV-2-infected pediatrics patients.

Detailed information on intrahost viral evolution in SARS-CoV-2 with and without treatment is limited. Sequential viral loads and deep sequencing of SARS-CoV-2 from the upper respiratory tract of nine hospitalized children, three of whom were treated with remdesivir, revealed that remdesivir treatment suppressed viral load in one patient but not in a second infected with an identical strain without any evidence of drug resistance found. Reduced levels of subgenomic RNA during treatment of the second patient, suggest an additional effect of remdesivir on viral replication. Haplotype reconstruction uncovered persistent SARS-CoV-2 variant genotypes in four patients. These likely arose from within-host evolution, although superinfection cannot be excluded in one case. Although our dataset is small, observed sample-to-sample heterogeneity in variant frequencies across four of nine patients suggests the presence of discrete viral populations in the lung with incomplete population sampling in diagnostic swabs. Such compartmentalization could compromise the penetration of remdesivir into the lung, limiting the drugs in vivo efficacy, as has been observed in other lung infections.

Synergistic use of glycomics and single-molecule molecular inversion probes for identification of congenital disorders of glycosylation type-1.

Congenital disorders of glycosylation type 1 (CDG-I) comprise a group of 27 genetic defects with heterogeneous multisystem phenotype, mostly presenting with nonspecific neurological symptoms. The biochemical hallmark of CDG-I is a partial absence of complete N-glycans on transferrin. However, recent findings of a diagnostic N-tetrasaccharide for ALG1-CDG and increased high-mannose N-glycans for a few other CDG suggested the potential of glycan structural analysis for CDG-I gene discovery. We analyzed the relative abundance of total plasma N-glycans by high resolution quadrupole time-of-flight mass spectrometry in a large cohort of 111 CDG-I patients with known (n = 75) or unsolved (n = 36) genetic cause. We designed single-molecule molecular inversion probes (smMIPs) for sequencing of CDG-I candidate genes on the basis of specific N-glycan signatures. Glycomics profiling in patients with known defects revealed novel features such as the N-tetrasaccharide in ALG2-CDG patients and a novel fucosylated N-pentasaccharide as specific glycomarker for ALG1-CDG. Moreover, group-specific high-mannose N-glycan signatures were found in ALG3-, ALG9-, ALG11-, ALG12-, RFT1-, SRD5A3-, DOLK-, DPM1-, DPM3-, MPDU1-, ALG13-CDG, and hereditary fructose intolerance. Further differential analysis revealed high-mannose profiles, characteristic for ALG12- and ALG9-CDG. Prediction of candidate genes by glycomics profiling in 36 patients with thus far unsolved CDG-I and subsequent smMIPs sequencing led to a yield of solved cases of 78% (28/36). Combined plasma glycomics profiling and targeted smMIPs sequencing of candidate genes is a powerful approach to identify causative mutations in CDG-I patient cohorts.

Effects of triheptanoin (UX007) in patients with long-chain fatty acid oxidation disorders: Results from an open-label, long-term extension study.

Long-chain fatty acid oxidation disorders (LC-FAOD) are autosomal recessive conditions that impair conversion of long-chain fatty acids into energy, leading to significant clinical symptoms. Triheptanoin is a highly purified, 7-carbon chain triglyceride approved in the United States as a source of calories and fatty acids for treatment of pediatric and adult patients with molecularly confirmed LC-FAOD. CL202 is an open-label, long-term extension study evaluating triheptanoin (Dojolvi) safety and efficacy in patients with LC-FAOD. Patients rolled over from the CL201 triheptanoin clinical trial (rollover); were triheptanoin-naïve (naïve); or had participated in investigator-sponsored trials/expanded access programs (IST/other). Results focus on rollover and naïve groups, as pretreatment data allow comparison. Primary outcomes were annual rate and duration of major clinical events (MCEs; rhabdomyolysis, hypoglycemia, and cardiomyopathy events). Seventy-five patients were enrolled (24 rollover, 20 naïve, 31 IST/other). Mean study duration was 23.0 months for rollover, 15.7 months for naïve, and 34.7 months for IST/other. In the rollover group, mean annualized MCE rate decreased from 1.76 events/year pre-triheptanoin to 0.96 events/year with triheptanoin (P = .0319). Median MCE duration was reduced by 66%. In the naïve group, median annualized MCE rate decreased from 2.33 events/year pre-triheptanoin to 0.71 events/year with triheptanoin (P = .1072). Median MCE duration was reduced by 80%. The most common related adverse events (AEs) were diarrhea, abdominal pain/discomfort, and vomiting, most mild to moderate. Three patients had serious AEs (diverticulitis, ileus, rhabdomyolysis) possibly related to drug; all resolved. Two patients had AEs leading to death; neither drug related. Triheptanoin reduced rate and duration of MCEs. Safety was consistent with previous observations.

Guidelines for the diagnosis and management of methylmalonic acidaemia and propionic acidaemia: First revision.

Isolated methylmalonic acidaemia (MMA) and propionic acidaemia (PA) are rare inherited metabolic diseases. Six years ago, a detailed evaluation of the available evidence on diagnosis and management of these disorders has been published for the first time. The article received considerable attention, illustrating the importance of an expert panel to evaluate and compile recommendations to guide rare disease patient care. Since that time, a growing body of evidence on transplant outcomes in MMA and PA patients and use of precursor free amino acid mixtures allows for updates of the guidelines. In this article, we aim to incorporate this newly published knowledge and provide a revised version of the guidelines. The analysis was performed by a panel of multidisciplinary health care experts, who followed an updated guideline development methodology (GRADE). Hence, the full body of evidence up until autumn 2019 was re-evaluated, analysed and graded. As a result, 21 updated recommendations were compiled in a more concise paper with a focus on the existing evidence to enable well-informed decisions in the context of MMA and PA patient care.

New insights into carnitine-acylcarnitine translocase deficiency from 23 cases: Management challenges and potential therapeutic approaches.

Carnitine acyl-carnitine translocase deficiency (CACTD) is a rare autosomal recessive disorder of mitochondrial long-chain fatty-acid transport. Most patients present in the first 2 days of life, with hypoketotic hypoglycaemia, hyperammonaemia, cardiomyopathy or arrhythmia, hepatomegaly and elevated liver enzymes. Multi-centre international retrospective chart review of clinical presentation, biochemistry, treatment modalities including diet, subsequent complications, and mode of death of all patients. Twenty-three patients from nine tertiary metabolic units were identified. Seven attenuated patients of Pakistani heritage, six of these homozygous c.82G>T, had later onset manifestations and long-term survival without chronic hyperammonemia. Of the 16 classical cases, 15 had cardiac involvement at presentation comprising cardiac arrhythmias (9/15), cardiac arrest (7/15), and cardiac hypertrophy (9/15). Where recorded, ammonia levels were elevated in all but one severe case (13/14 measured) and 14/16 had hypoglycaemia. Nine classical patients survived longer-term-most with feeding difficulties and cognitive delay. Hyperammonaemia appears refractory to ammonia scavenger treatment and carglumic acid, but responds well to high glucose delivery during acute metabolic crises. High-energy intake seems necessary to prevent decompensation. Anaplerosis utilising therapeutic d,l-3-hydroxybutyrate, Triheptanoin and increased protein intake, appeared to improve chronic hyperammonemia and metabolic stability where trialled in individual cases. CACTD is a rare disorder of fatty acid oxidation with a preponderance to severe cardiac dysfunction. Long-term survival is possible in classical early-onset cases with long-chain fat restriction, judicious use of glucose infusions, and medium chain triglyceride supplementation. Adjunctive therapies supporting anaplerosis may improve longer-term outcomes.

Efficacy and safety of arimoclomol in Niemann-Pick disease type C: Results from a double-blind, randomised, placebo-controlled, multinational phase 2/3 trial of a novel treatment.

Niemann-Pick disease type C (NPC) is a rare, genetic, progressive neurodegenerative disorder with high unmet medical need. We investigated the safety and efficacy of arimoclomol, which amplifies the heat shock response to target NPC protein misfolding and improve lysosomal function, in patients with NPC. In a 12-month, prospective, randomised, double-blind, placebo-controlled, phase 2/3 trial (ClinicalTrials.gov identifier: NCT02612129), patients (2-18 years) were randomised 2:1 to arimoclomol:placebo, stratified by miglustat use. Routine clinical care was maintained. Arimoclomol was administered orally three times daily. The primary endpoint was change in 5-domain NPC Clinical Severity Scale (NPCCSS) score from baseline to 12 months. Fifty patients enrolled; 42 completed. At month 12, the mean progression from baseline in the 5-domain NPCCSS was 0.76 with arimoclomol vs 2.15 with placebo. A statistically significant treatment difference in favour of arimoclomol of -1.40 (95% confidence interval: -2.76, -0.03; P = .046) was observed, corresponding to a 65% reduction in annual disease progression. In the prespecified subgroup of patients receiving miglustat as routine care, arimoclomol resulted in stabilisation of disease severity over 12 months with a treatment difference of -2.06 in favour of arimoclomol (P = .006). Adverse events occurred in 30/34 patients (88.2%) receiving arimoclomol and 12/16 (75.0%) receiving placebo. Fewer patients had serious adverse events with arimoclomol (5/34, 14.7%) vs placebo (5/16, 31.3%). Treatment-related serious adverse events (n = 2) included urticaria and angioedema. Arimoclomol provided a significant and clinically meaningful treatment effect in NPC and was well tolerated.

International consensus guidelines for phosphoglucomutase 1 deficiency (PGM1-CDG): Diagnosis, follow-up, and management.

Phosphoglucomutase 1 (PGM1) deficiency is a rare genetic disorder that affects glycogen metabolism, glycolysis, and protein glycosylation. Previously known as GSD XIV, it was recently reclassified as a congenital disorder of glycosylation, PGM1-CDG. PGM1-CDG usually manifests as a multisystem disease. Most patients present as infants with cleft palate, liver function abnormalities and hypoglycemia, but some patients present in adulthood with isolated muscle involvement. Some patients develop life-threatening cardiomyopathy. Unlike most other CDG, PGM1-CDG has an effective treatment option, d-galactose, which has been shown to improve many of the patients' symptoms. Therefore, early diagnosis and initiation of treatment for PGM1-CDG patients are crucial decisions. In this article, our group of international experts suggests diagnostic, follow-up, and management guidelines for PGM1-CDG. These guidelines are based on the best available evidence-based data and experts' opinions aiming to provide a practical resource for health care providers to facilitate successful diagnosis and optimal management of PGM1-CDG patients.

Phosphoglucomutase-1 deficiency: Early presentation, metabolic management and detection in neonatal blood spots.

Phosphoglucomutase 1 deficiency is a congenital disorder of glycosylation (CDG) with multiorgan involvement affecting carbohydrate metabolism, N-glycosylation and energy production. The metabolic management consists of dietary D-galactose supplementation that ameliorates hypoglycemia, hepatic dysfunction, endocrine anomalies and growth delay. Previous studies suggest that D-galactose administration in juvenile patients leads to more significant and long-lasting effects, stressing the urge of neonatal diagnosis (0-6 months of age). Here, we detail the early clinical presentation of PGM1-CDG in eleven infantile patients, and applied the modified Beutler test for screening of PGM1-CDG in neonatal dried blood spots (DBSs). All eleven infants presented episodic hypoglycemia and elevated transaminases, along with cleft palate and growth delay (10/11), muscle involvement (8/11), neurologic involvement (5/11), cardiac defects (2/11). Standard dietary measures for suspected lactose intolerance in four patients prior to diagnosis led to worsening of hypoglycemia, hepatic failure and recurrent diarrhea, which resolved upon D-galactose supplementation. To investigate possible differences in early vs. late clinical presentation, we performed the first systematic literature review for PGM1-CDG, which highlighted respiratory and gastrointestinal symptoms as significantly more diagnosed in neonatal age. The modified Butler-test successfully identified PGM1-CDG in DBSs from seven patients, including for the first time Guthrie cards from newborn screening, confirming the possibility of future inclusion of PGM1-CDG in neonatal screening programs. In conclusion, severe infantile morbidity of PGM1-CDG due to delayed diagnosis could be prevented by raising awareness on its early presentation and by inclusion in newborn screening programs, enabling early treatments and galactose-based metabolic management.

Inborn errors of metabolism leading to neuronal migration defects.

The development and organisation of the human brain start in the embryonic stage and is a highly complex orchestrated process. It depends on series of cellular mechanisms that are precisely regulated by multiple proteins, signalling pathways and non-protein-coding genes. A crucial process during cerebral cortex development is the migration of nascent neuronal cells to their appropriate positions and their associated differentiation into layer-specific neurons. Neuronal migration defects (NMD) comprise a heterogeneous group of neurodevelopmental disorders including monogenetic disorders and residual syndromes due to damaging factors during prenatal development like infections, maternal diabetes mellitus or phenylketonuria, trauma, and drug use. Multifactorial causes are also possible. Classification into lissencephaly, polymicrogyria, schizencephaly, and neuronal heterotopia is based on the visible morphologic cortex anomalies. Characteristic clinical features of NMDs are severe psychomotor developmental delay, severe intellectual disability, intractable epilepsy, and dysmorphisms. Neurometabolic disorders only form a small subgroup within the large group of NMDs. The prototypes are peroxisomal biogenesis disorders, peroxisomal ß-oxidation defects and congenital disorders of O-glycosylation. The rapid evolution of biotechnology has resulted in an ongoing identification of metabolic and non-metabolic disease genes for NMDs. Nevertheless, we are far away from understanding the specific role of cortical genes and metabolites on spatial and temporal regulation of human cortex development and associated malformations. This limited understanding of the pathogenesis hinders the attempt for therapeutic approaches. In this article, we provide an overview of the most important cortical malformations and potential underlying neurometabolic disorders.

Predominant and novel de novo variants in 29 individuals with ALG13 deficiency: Clinical description, biomarker status, biochemical analysis, and treatment suggestions.

Asparagine-linked glycosylation 13 homolog (ALG13) encodes a nonredundant, highly conserved, X-linked uridine diphosphate (UDP)-N-acetylglucosaminyltransferase required for the synthesis of lipid linked oligosaccharide precursor and proper N-linked glycosylation. De novo variants in ALG13 underlie a form of early infantile epileptic encephalopathy known as EIEE36, but given its essential role in glycosylation, it is also considered a congenital disorder of glycosylation (CDG), ALG13-CDG. Twenty-four previously reported ALG13-CDG cases had de novo variants, but surprisingly, unlike most forms of CDG, ALG13-CDG did not show the anticipated glycosylation defects, typically detected by altered transferrin glycosylation. Structural homology modeling of two recurrent de novo variants, p.A81T and p.N107S, suggests both are likely to impact the function of ALG13. Using a corresponding ALG13-deficient yeast strain, we show that expressing yeast ALG13 with either of the highly conserved hotspot variants rescues the observed growth defect, but not its glycosylation abnormality. We present molecular and clinical data on 29 previously unreported individuals with de novo variants in ALG13. This more than doubles the number of known cases. A key finding is that a vast majority of the individuals presents with West syndrome, a feature shared with other CDG types. Among these, the initial epileptic spasms best responded to adrenocorticotropic hormone or prednisolone, while clobazam and felbamate showed promise for continued epilepsy treatment. A ketogenic diet seems to play an important role in the treatment of these individuals.

Bullying bystander behaviors: The role of coping effectiveness and the moderating effect of gender.

Researchers have suggested that bystander behaviors and victim coping play an important role in counteracting the negative effects of bullying. The current study investigated the relationship between students' ratings of coping effectiveness when addressing bullying and their behaviors as bystanders when witnessing bullying. Surveys were administered in a Midwestern, suburban school district. Some associations between perceptions of coping effectiveness and bystander behavior supported our hypotheses (e.g., constructive coping associated with defending bystander behaviors, externalizing associated with pro-bullying behaviors). However, some findings did not support hypothesized relationships. For example, higher ratings of effectiveness for cognitive distancing as a coping strategy were associated with increased defending behaviors as a bystander. Gender moderated some of these relationships. Pro-bullying bystander behavior was associated with increased ratings of cognitive distancing and decreased reports of constructive coping effectiveness for girls. Implications for future research and practice are discussed.