Metabolic Control and Frequency of Clinical Monitoring Among Canadian Children With Phenylalanine Hydroxylase Deficiency: A Retrospective Cohort Study.

Achieving and maintaining metabolic control is critical for children with phenylalanine hydroxylase (PAH) deficiency. This retrospective longitudinal cohort study investigated metabolic control and monitoring frequency of children with PAH deficiency (≤ 12 years) treated at one of 12 pediatric metabolic centres across Canada. We abstracted data from medical charts and analyzed outcomes by age and diagnostic classification, using mixed effects regression.

Establishing a core outcome set for creatine transporter deficiency and guanidinoacetate methyltransferase deficiency.

Background: Creatine transporter (CTD) and guanidinoacetate methyltransferase (GAMT) deficiencies are rare inborn errors of creatine metabolism, resulting in cerebral creatine deficiency. Patients with either condition commonly exhibit intellectual and developmental disabilities, often accompanied by behavior problems, delayed speech, seizures, and motor impairments. There is currently no efficacious treatment for CTD, while current management for GAMT requires lifelong treatment with a protein restricted diet and intake of high amounts of oral supplements.

The Spectrum of Neurologic Phenotypes Associated With NUS1 Pathogenic Variants: A Comprehensive Case Series.

Objective: A growing body of evidence indicates a strong genetic overlap between developmental and epileptic encephalopathies (DEEs) and movement disorders. De novo loss-of-function variants in NUS1 have been recently identified in DEE cases. Herein, we report a large cohort of cases with pathogenic NUS1 variants and describe their clinical presentation and the details of the associated epilepsy and movement disorders.

Functional Characterization of Variants in : Report of Three New Individuals With Alazami Syndrome and a Literature Review.

Biallelic pathogenic variants in result in Alazami syndrome, which is characterized by global developmental delay, cognitive dysfunction, and dysmorphic features. Cardiac and skeletal phenotypes are reported in about 30% of individuals. We report three new individuals with Alazami syndrome and functional characterization of variants in this study.

Never Late: Cerebrotendinous Xanthomatosis and Improvements in Neurocognitive Functions in an Adult Patient on Chenodeoxycholic Acid Treatment.

Cerebrotendinous xanthomatosis (CTX) is an inherited metabolic disease due to biallelic pathogenic variants in CYP27A1. We report a newly diagnosed patient and the outcome of the chenodeoxycholic acid (CDCA) treatment. This is a 36-year-old male with progressive lower limb spasticity, learning difficulties, and early cataracts.

Outcome of creatine supplementation therapy in phosphoglucomutase-1 deficiency associated congenital disorders of glycosylation: Novel insights.

Background: Biallelic pathogenic variants in result in phosphoglucomutase 1 (PGM1) deficiency that is one of the congenital disorders of glycosylation (CDG) (PGM1-CDG). Phenotypic spectrum includes congenital malformations, and muscular, cardiac, hepatic, endocrine and hematologic phenotypes. Current treatment consists of D-galactose therapy that results in clinical and biochemical improvements.

MBOAT7 encephalopathy: Characterizing the neurology and epileptology.

Objective: Biallelic pathogenic MBOAT7 variants are associated with neurodevelopmental disorders, intellectual disability (ID), epilepsy, and neuropsychiatric disorders such as attention-deficit/hyperactivity disorder and autism spectrum disorders. We aimed to characterize the epilepsy phenotype in a cohort of patients affected by this syndrome.

Methods: We describe epilepsy features, electroencephalography, magnetic resonance imaging (MRI) findings, antiseizure treatment response, and neurodevelopment of 15 patients with biallelic MBOAT7 variants.

Heterozygous CELF4 variants in the N-term region crucial for the RNA-binding activity lead to neurodevelopmental disorder and obesity.

RNA-binding proteins play a key role in post-transcriptional events, such as mRNA splicing, transport, stability, translation and decay. Dysregulation of RNA life can have dramatic consequences. CELF RNA-binding proteins appear to be essential during embryo development.

Neonatal Encephalopathy: Novel Phenotypes and Genotypes Identified by Genome Sequencing.

Background And Objectives: Neonatal encephalopathy (NE) is characterized by an abnormal level of consciousness with or without seizures in the neonatal period. It affects 1-6/1,000 live term newborns. We applied genome sequencing (GS) in term newborns with NE to investigate the underlying genetic causes.

Reduced guanidinoacetate in plasma of patients with autosomal dominant Fanconi syndrome due to heterozygous P341L variant and study of organoids towards treatment.

Autosomal dominant Fanconi syndrome due to a variant (GATM-FS), causes accumulation of misfolded arginine-glycine amidinotransferase (AGAT) in proximal renal tubules leading to cellular injury. GATM-FS presents during childhood and progresses to end-stage kidney disease (ESKD) in adults. We study creatine metabolism in two individuals of unrelated families with a known variant and the effect of creatine supplementation in kidney organoids.

Review of clinical trials and guidelines for children and youth with mucopolysaccharidosis: outcome selection and measurement.

Background: To inform the development of a core outcome set (COS) for children and youth with mucopolysaccharidoses (MPS), we aimed to identify all outcomes and associated outcome measurement instruments that are reported in recent clinical trials and recommended as measurements in clinical management guidelines.

Methods: To identify English-language clinical trials and guidelines pertaining to MPS published between 2011 and mid-2021, we applied a comprehensive peer-reviewed search strategy to relevant databases and registers on May 16, 2021. Two reviewers independently screened retrieved citations and then full-text articles to determine eligibility for inclusion.

Dissecting CASK: Novel splice site variant associated with male MICPCH phenotype.

CASK (MIM#300172), encoding a calcium/calmodulin-dependent serine protein kinase, is crucial for synaptic transmission and gene regulation during neural development. Pathogenic variants of CASK are known to cause several neurodevelopmental disorders, including X-linked intellectual disability and microcephaly with pontine and cerebellar hypoplasia (MICPCH). This study introduces a novel, de novo synonymous CASK variant (NM_001367721.

Coagulation abnormalities and vascular complications are common in PGM1-CDG.

Phosphoglucomutase-1-congenital disorder of glycosylation (PGM1-CDG) is a rare genetic disorder caused by biallelic variants in the PGM1 gene, leading to the deficiency of the PGM1 enzyme. The most common clinical presentations include muscle involvement, failure to thrive, cleft palate, and cardiac involvement. Abnormal serum N-glycosylation, hypoglycemia, and liver function abnormalities including coagulation abnormalities are the most common laboratory abnormalities.

Etiological involvement of KCND1 variants in an X-linked neurodevelopmental disorder with variable expressivity.

Utilizing trio whole-exome sequencing and a gene matching approach, we identified a cohort of 18 male individuals from 17 families with hemizygous variants in KCND1, including two de novo missense variants, three maternally inherited protein-truncating variants, and 12 maternally inherited missense variants. Affected subjects present with a neurodevelopmental disorder characterized by diverse neurological abnormalities, mostly delays in different developmental domains, but also distinct neuropsychiatric signs and epilepsy. Heterozygous carrier mothers are clinically unaffected.

Brainstem Chipmunk Sign: A Diagnostic Imaging Clue across All Subtypes of Alexander Disease.

Background And Purpose: While classic brain MR imaging features of Alexander disease have been well-documented, lesional patterns can overlap with other leukodystrophies, especially in the early stages of the disease or in milder phenotypes. We aimed to assess the utility of a new neuroimaging sign to help increase the diagnostic specificity of Alexander disease.

Materials And Methods: A peculiar bilateral symmetric hyperintense signal on T2-weighted images affecting the medulla oblongata was identified in an index patient with type I Alexander disease.

Dodecyl creatine ester therapy: from promise to reality.

Pathogenic variants in SLC6A8, the gene which encodes creatine transporter SLC6A8, prevent creatine uptake in the brain and result in a variable degree of intellectual disability, behavioral disorders (e.g., autism spectrum disorder), epilepsy, and severe speech and language delay.

Importance of the biochemical investigations for the functional characterization of a NPC1 variant identified by exome sequencing.

Niemann-Pick disease type C (NPC) is one of the lysosomal storage disorders. It is caused by biallelic pathogenic variants in NPC1 or NPC2, which results in a defective cholesterol trafficking inside the late endosome and lysosome. There is a high clinical variability in the age of presentation and the phenotype of this disorder making the diagnosis challenging.

The continuously evolving phenotype of succinic semialdehyde dehydrogenase deficiency.

The objective of the study is to evaluate the evolving phenotype and genetic spectrum of patients with succinic semialdehyde dehydrogenase deficiency (SSADHD) in long-term follow-up. Longitudinal clinical and biochemical data of 22 pediatric and 9 adult individuals with SSADHD from the patient registry of the International Working Group on Neurotransmitter related Disorders (iNTD) were studied with in silico analyses, pathogenicity scores and molecular modeling of ALDH5A1 variants. Leading initial symptoms, with onset in infancy, were developmental delay and hypotonia.

Clinical and biochemical phenotypes, genotypes, and long-term outcomes of individuals with galactosemia type I from a single metabolic genetics center in Alberta.

Background: Galactosemia type I is an autosomal recessive disorder of galactose metabolism due to galactose-1-phosphate uridyltransferase deficiency, encoded by . To investigate the phenotypes, genotypes and long-term outcomes of galactosemia, we performed a retrospective cohort study in our center.

Methods: All individuals with galactosemia type I were included.

ClinGen variant curation expert panel recommendations for classification of variants in GAMT, GATM and SLC6A8 for cerebral creatine deficiency syndromes.

Cerebral creatine deficiency syndromes (CCDS) are inherited metabolic phenotypes of creatine synthesis and transport. There are two enzyme deficiencies, guanidinoacetate methyltransferase (GAMT), encoded by GAMT and arginine-glycine amidinotransferase (AGAT), encoded by GATM, which are involved in the synthesis of creatine. After synthesis, creatine is taken up by a sodium-dependent membrane bound creatine transporter (CRTR), encoded by SLC6A8, into all organs.

A position statement on the post gene-therapy rehabilitation of aromatic I-amino acid decarboxylase deficiency patients.

Aromatic L-amino acid decarboxylase (AADC) deficiency is a rare genetic disorder of monoamine neurotransmitter synthesis that presents with a range of symptoms, including motor dysfunction and limited attainment of developmental motor milestones. The approval of eladocagene exuparvovec, a gene therapy for AADC deficiency with demonstrated efficacy for motor improvements, now expands the range of motor outcomes possible for patients with this disorder. However, recommendations and guidelines for therapy following treatment with gene therapy are lacking.