Fatal cervical myelopathy in a child with glutaric aciduria type 1.

We report the case of a Syrian female refugee with late diagnosis of glutaric aciduria type 1 characterised by massive axial hypotonia and quadriplegia who only started adequate diet upon arrival in Switzerland at the age of 4 years, after a strenuous migration journey. Soon after arrival, she died from an unexpected severe upper cervical myelopathy, heralded by acute respiratory distress after a viral infection. This was likely due to repeated strains on her hypotonic neck and precipitated by an orthotopic os odontoideum who led to atlanto-axial subluxation. This case reminds us not to omit handling patients with insufficient postural control and hypotonia with great care to avoid progressive cervical myelopathy.

Clinico-Biochemical Spectrum of Pakistani Patients with Glutaric Aciduria Type 1 (GA1): Experience from a Specialised Biochemical Genetics Laboratory in Pakistan.

OBJECTIVE: To evaluate the clinical, radiological, and biochemical features of glutaric aciduria Type 1 (GA1) patients identified through urine organic acid testing at a biochemical genetics laboratory (BGL) in Pakistan. STUDY DESIGN: Observational study. Place and Duration of the Study: Department of Pathology and Laboratory Medicine, The Aga Khan University Hospital, Karachi, Pakistan, from January 2013 to December 2022. METHODOLOGY: Medical charts and urine organic acid (UOA) chromatograms of the patients presenting at the BGL from January 2013 to December 2022 were reviewed. Brain imaging was obtained where available. Variables were noted as per the objective and descriptive statistics were obtained. RESULTS: GA1 was found in 64 (0.4%) patients out of a total of 16,094 UOA requests for high-risk screening cases. The age of diagnosis ranged between one month and three years. The brain MRI findings revealed characteristic abnormalities such as cerebral atrophy, expanded CSF spaces, white matter abnormalities, and a distinct bat wings appearance, in cohesion with the results of biochemical testing. CONCLUSION: Sixty-four cases of GA1 from a single centre indicate a high frequency of the disorder in Pakistan. Late diagnosis emphasises the need for increased clinical awareness and preferably newborn screening to ensure optimal outcomes. KEY WORDS: Glutaric aciduria Type 1 (GA1), Brain imaging, UOA analysis, Glutaryl-CoA dehydrogenase (GCDH), Pakistan.

Evaluation of the first 5 years of a glutaric aciduria type I neonatal screening programme in Asturias.

INTRODUCTION: . Neonatal screening of glutaric aciduria type 1 (GA-1) has brought radical changes in the course and outcomes of this disease. This study analyses the outcomes of the first 5 years (2015-2019) of the AGA1 neonatal screening programme in our autonomous community. MATERIAL: . We conducted an observational, descriptive and retrospective study. All neonates born between January 1, 2015 and December 31, 2019 that participated in the neonatal screening programme were included in the study. The glutarylcarnitine (C5DC) concentration in dry blood spot samples was measured by means of tandem mass spectrometry applying a cut-off point of 0.25 µmol/L. RESULTS: . A total of 30 120 newborns underwent screening. We found differences in the C5DC concentration based on gestational age, type of feeding and hours of life at sample collection. These differences were not relevant for screening purposes. There were no differences between neonates with weights smaller and greater than 1500 g. Screening identified 2 affected patients and there were 3 false positives. There were no false negatives. The diagnosis was confirmed by genetic testing. Patients have been in treatment since diagnosis and have not developed encephalopathic crises in the first 4 years of life. CONCLUSIONS: . Screening allowed early diagnosis of two cases of GA-1 in the first 5 years since its introduction in our autonomous community. Although there were differences in C5DC levels based on gestational age, type of feeding and hours of life at blood extraction, they were not relevant for screening.

Generation of hiPSC lines from four glutaric aciduria type I (GA1) patients carrying pathogenic biallelic variants in GCDH.

GCDH encodes for the enzyme catalyzing the sixth step of the lysine degradation pathway. Autosomal recessive variants in GCDH are associated with glutaric aciduria type I (GA1), of which a wide genotypic spectrum of pathogenic variants have been described. In this study, hiPSC lines derived from four GA1 patients with different genotypes were generated and fully characterized. Two patients carry compound heterozygous variants in GCDH, while the other two patients carry a variant in homozygosis. These hiPSC lines can significantly contribute to better understand the molecular mechanism underlying GA1 and provide excellent models for the development of new therapeutic strategies.

Comprehensive metabolomics analysis reveals novel biomarkers and pathways in falsely suspected glutaric aciduria Type-1 newborns.

BACKGROUND: Glutaric aciduria type-1 (GA-1) is a rare metabolic disorder due to glutaryl coenzyme A dehydrogenase deficiency, causing elevated levels of glutaryl-CoA and its derivatives. GA-1 exhibits symptoms like macrocephaly, developmental delays, and movement disorders. Timely diagnosis through genetic testing and newborn screening is crucial. However, in some cases, transiently elevated level of glutarylcarnitine (C5DC) challenges accurate diagnosis, highlighting the need for alternative diagnostic methods, like mass spectrometry-based untargeted metabolomics, to identify additional biomarkers for distinguishing falsely suspected GA-1 from healthy newborns. METHODOLOGY: DBS samples from falsely suspected GA-1 newborns (n = 47) and matched control were collected through the NBS program. Untargeted metabolomics using liquid chromatography-high-resolution mass spectrometry (LC-HRMS) was performed to enable biomarker and pathway investigations for significantly altered metabolites. RESULTS: 582 and 546 were up- and down-regulated metabolites in transient GA-1. 155 endogenous metabolites displayed significant variations compared to the control group. Furthermore, our data identified novel altered metabolic biomarkers, such as N-palmitoylcysteine, heptacarboxyporphyrin, 3-hydroxylinoleoylcarnitine, and monoacylglyceride (MG) (0:0/20:1/0:0), along with perturbed metabolic pathways like sphingolipid and thiamine metabolism associated with the transient elevated C5DC levels in DBS samples. CONCLUSIONS: A distinct metabolic pattern linked to the transient C5DC elevation in newborns was reported to enhance the prediction of the falsely positive cases, which could help avoiding unnecessary medical treatments and minimizing the financial burdens in the health sector.

Cerebral White Matter Alterations Associated With Oligodendrocyte Vulnerability in Organic Acidurias: Insights in Glutaric Aciduria Type I.

The white matter is an important constituent of the central nervous system, containing axons, oligodendrocytes, and its progenitor cells, astrocytes, and microglial cells. Oligodendrocytes are central for myelin synthesis, the insulating envelope that protects axons and allows normal neural conduction. Both, oligodendrocytes and myelin, are highly vulnerable to toxic factors in many neurodevelopmental and neurodegenerative disorders associated with disturbances of myelination. Here we review the main alterations in oligodendrocytes and myelin observed in some organic acidurias/acidemias, which correspond to inherited neurometabolic disorders biochemically characterized by accumulation of potentially neurotoxic organic acids and their derivatives. The yet incompletely understood mechanisms underlying the high vulnerability of OLs and/or myelin in glutaric acidemia type I, the most prototypical cerebral organic aciduria, are particularly discussed.

Characterization, Structure, and Inhibition of the Human Succinyl-CoA:glutarate-CoA Transferase, a Putative Genetic Modifier of Glutaric Aciduria Type 1.

Glutaric Aciduria Type 1 (GA1) is a serious inborn error of metabolism with no pharmacological treatments. A novel strategy to treat this disease is to divert the toxic biochemical intermediates to less toxic or nontoxic metabolites. Here, we report a putative novel target, succinyl-CoA:glutarate-CoA transferase (SUGCT), which we hypothesize suppresses the GA1 metabolic phenotype through decreasing glutaryl-CoA and the derived 3-hydroxyglutaric acid. SUGCT is a type III CoA transferase that uses succinyl-CoA and glutaric acid as substrates. We report the structure of SUGCT, develop enzyme- and cell-based assays, and identify valsartan and losartan carboxylic acid as inhibitors of the enzyme in a high-throughput screen of FDA-approved compounds. The cocrystal structure of SUGCT with losartan carboxylic acid revealed a novel pocket in the active site and further validated the high-throughput screening approach. These results may form the basis for the future development of new pharmacological intervention to treat GA1.

Compilation of Genotype and Phenotype Data in GCDH-LOVD for Variant Classification and Further Application.

Glutaric aciduria type 1 (GA-1) is a rare but treatable autosomal-recessive neurometabolic disorder of lysin metabolism caused by biallelic pathogenic variants in glutaryl-CoA dehydrogenase gene (GCDH) that lead to deficiency of GCDH protein. Without treatment, this enzyme defect causes a neurological phenotype characterized by movement disorder and cognitive impairment. Based on a comprehensive literature search, we established a large dataset of GCDH variants using the Leiden Open Variation Database (LOVD) to summarize the known genotypes and the clinical and biochemical phenotypes associated with GA-1. With these data, we developed a GCDH-specific variation classification framework based on American College of Medical Genetics and Genomics and the Association for Molecular Pathology guidelines. We used this framework to reclassify published variants and to describe their geographic distribution, both of which have practical implications for the molecular genetic diagnosis of GA-1. The freely available GCDH-specific LOVD dataset provides a basis for diagnostic laboratories and researchers to further optimize their knowledge and molecular diagnosis of this rare disease.