Adult-onset glutaric aciduria type I: rare presentation of a treatable disorder

Acute myeloneuropathy due to Glutaric aciduria-1: Expanding the phenotypic spectrum

Glutaric aciduria type-1 (GA-1) is a rare metabolic disorder due to mutation in GCDH gene resulting in varied clinical manifestations. Here we report a case of late-onset GA-1 with acute myelo-neuropathy and chronic renal failure. Institutional ethics committee approval was obtained and genetic analysis was done by clinical exome sequencing. Here we present 19 year-old-adolescent male with chronic renal disease for 2 years presented with 5 months history of sudden onset weakness of proximal and distal lower limbs and bladder retention. This was preceded by recurrent episodes of vomiting. On clinical examination he had features of myeloneuropathy. Laboratory evaluation showed significant elevation of blood glutaryl carnitine with very low free carnitine, while extensive white matter signal changes with diffusion restriction, subependymal nodules and involvement of internal capsule were evidenced on brain magnetic resonance imaging. Diagnosis was confirmed by clinical exome sequencing which showed a pathogenic homozygous missense mutation in exon 11 of GCDH gene (c .120 C>T, p.His403Tyr). This report expands phenotypic spectrum of GA-1 to include late onset acute myelo-neuropathy with chronic renal failure. A high index of suspicion is required since early treatment might decelerate further disease progression.

Glutaric aciduria type 1: Insights into diagnosis and neurogenetic outcomes

Glutaric aciduria type 1 (GA1) is a rare metabolic disorder characterized by a deficiency in the enzyme glutaryl-CoA dehydrogenase. This study aims to present the clinical, biochemical, genetic, and neuroimaging findings of GA1 patients, emphasizing the importance of early detection and the potential benefits of incorporating GA1 into NBS programs. The demographic, clinical, and laboratory findings of GA1 patients were reviewed retrospectively. This study presents the clinical, biochemical, genetic, and neuroimaging findings of 15 patients (six males, nine females) from 13 families diagnosed with GA1. The median age at diagnosis was 20 months, and the median follow-up period was 72 months. Developmental delay was observed in 66.7% of patients, with 46.7% experiencing seizures and 33.3% suffering from encephalopathic crises. Biochemical analyses showed elevated levels of glutaric acid and 3-hydroxyglutaric acid in 93.3% and 80% of patients, respectively. Genetic testing identified the p.Arg402Trp variant in 53.3% of patients. Neurological evaluations revealed delays in motor and speech development, with 66.7% of patients never achieving the ability to walk. Cranial MRI indicated white matter changes in all patients and basal ganglia involvement in 93.3%. Despite significant biochemical improvements with treatment in glutaric acid levels and head circumference over time, neurological deficits remain unchanged. Growth parameters such as body weight showed significant decreases due to poor neurological outcomes.

CONCLUSION

The study underscores the importance of early diagnosis and intervention to mitigate severe neurological outcomes. Our findings highlight the need for incorporating GA1 into newborn screening programs to ensure timely diagnosis and treatment.

WHAT IS KNOWN

• Glutaric aciduria type 1 (GA1) is a rare metabolic disorder caused by a deficiency of glutaryl-CoA dehydrogenase. If untreated, it often leads to severe neurological complications. Early diagnosis and treatment are crucial for improving clinical outcomes in GA1 patients.

WHAT IS NEW

• This study presents comprehensive data from a cohort of 15 Glutaric aciduria type 1 (GA1) patients, detailing their biochemical, genetic, clinical, and neuroimaging findings. Drawing attention to the severe neurological findings in late-diagnosed patients underscores the critical importance of including GA1 in newborn screening programs to enhance early diagnosis and prevent severe outcomes.

Metagenomic Analysis Reveals Large-Scale Disruptions of the Gut Microbiome in Parkinson's Disease

BACKGROUND

Parkinson's disease (PD) has been consistently linked to alterations within the gut microbiome.

OBJECTIVE

Our goal was to identify microbial features associated with PD incidence and progression.

METHODS

Metagenomic sequencing was used to characterize taxonomic and functional changes to the PD microbiome and to explore their relation to bacterial metabolites and disease progression. Motor and non-motor symptoms were tracked using Movement Disorder Society Unified Parkinson's Disease Rating Scale (MDS-UPDRS) and levodopa equivalent dose across ≤5 yearly study visits. Stool samples were collected at baseline for metagenomic sequencing (176 PD, 100 controls).

RESULTS

PD-derived stool samples had reduced intermicrobial connectivity and seven differentially abundant species compared to controls. A suite of bacterial functions differed between PD and controls, including depletion of carbohydrate degradation pathways and enrichment of ribosomal genes. Faecalibacterium prausnitzii-specific reads contributed significantly to more than half of all differentially abundant functional terms. A subset of disease-associated functional terms correlated with faster progression of MDS-UPDRS part IV and separated those with slow and fast progression with moderate accuracy within a random forest model (area under curve = 0.70). Most PD-associated microbial trends were stronger in those with symmetric motor symptoms.

CONCLUSION

We provide further evidence that the PD microbiome is characterized by reduced intermicrobial communication and a shift to proteolytic metabolism in lieu of short-chain fatty acid production, and suggest that these microbial alterations may be relevant to disease progression. We also describe how our results support the existence of gut-first versus brain-first PD subtypes. © 2024 The Author(s). Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Prenatal Ultrasound and Magnetic Resonance Findings of Glutaric Acidemia Type 1 and Its Challenges in Prenatal Diagnosis

Glutaric acidemia type 1 (GA1) presents unique challenges in prenatal diagnosis, especially in cases with no family history. This review article aims to review and present the prenatal ultrasound and magnetic resonance findings of GA1 and consolidate key insights into the difficulties associated with GA1 prenatal diagnosis and the neuroimaging features that require careful differentiation during the diagnostic process.

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.

Update current understanding of neurometabolic disorders related to lysine metabolism

Lysine, as an essential amino acid, predominantly undergoes metabolic processes through the saccharopine pathway, whereas a smaller fraction follows the pipecolic acid pathway. Although the liver is considered the primary organ for lysine metabolism, it is worth noting that lysine catabolism also takes place in other tissues and organs throughout the body, including the brain. Enzyme deficiency caused by pathogenic variants in its metabolic pathway may lead to a series of neurometabolic diseases, among which glutaric aciduria type 1 and pyridoxine-dependent epilepsy have the most significant clinical manifestations. At present, through research, we have a deeper understanding of the multiple pathophysiological mechanisms related to these diseases, including intracerebral accumulation of neurotoxic metabolites, imbalance between GABAergic and glutamatergic neurotransmission, energy deprivation due to metabolites, and the dysfunction of antiquitin. Because of the complexity of these diseases, their clinical manifestations are also diverse. The early implementation of lysine-restricted diets and supplementation with arginine and carnitine has reported positive impacts on the neurodevelopmental outcomes of patients. Presently, there is more robust evidence supporting the effectiveness of these treatments in glutaric aciduria type 1 compared with pyridoxine-dependent epilepsy.

Two novel compound heterozygous variants of the GCDH gene in two Chinese families with glutaric acidaemia type I identified by high-throughput sequencing and a literature review

Autosomal recessive glutaric acidaemia type I (GA-I) is a rare hereditary metabolic disease characterized by increased organic acids and neurologic symptoms. Although numerous variants in the GCDH gene have been identified to be connected with the pathogenesis of GA-I, the relationship between genotype and phenotype remains uncertain. In this study, we evaluated genetic data for two GA-I patients from Hubei, China, and we reviewed the previous research findings to clarify the genetic heterogeneity of GA-I and identify the potential causative variants. After we extracted genomic DNA from peripheral blood samples obtained from two unrelated Chinese families, we used target capture high-throughput sequencing combined with Sanger sequencing to determine likely pathogenic variants in the two probands. Electronic databases were also searched for the literature review. The genetic analysis revealed two compound heterozygous variants in the GCDH gene expected to lead to GA-I in the two probands (P1 and P2), with P1 carrying two known variants (c.892G > A/p. A298T and c.1244-2A > C/IVS10-2A > C) and P2 harbouring two novel variants (c.370G > T/p.G124W and c.473A > G/p.E158G). In the literature review, the most common alleles in low excretors (i.e., individuals with low excretion of GA) were R227P, V400M, M405V, and A298T, with variation in the severity of clinical phenotypes. Overall, we identified two novel GCDH gene candidate pathogenic variants in a Chinese patient, enriching the GCDH gene mutational spectrum and providing a solid foundation for the early diagnosis of GA-I patients with low excretion.

Glutaric aciduria type 1: Diagnosis, clinical features and long-term outcome in a large cohort of 34 Irish patients

Glutaric aciduria type 1 (GA1) is a rare neurometabolic disorder that can lead to encephalopathic crises and severe dystonic movement disorders. Adherence to strict dietary restriction, in particular a diet low in lysine, carnitine supplementation and emergency treatment in pre-symptomatic patients diagnosed by high-risk screen (HRS) or newborn screen (NBS) leads to a favourable outcome. We present biochemical and clinical characteristics and long-term outcome data of 34 Irish patients with GA1 aged 1-40 years. Sixteen patients were diagnosed clinically, and 17 patients by HRS, prior to introduction of NBS for GA1 in the Republic of Ireland in 2018. One patient was diagnosed by NBS. Clinical diagnosis was at a median of 1 year (range 1 month to 8 years) and by HRS was at a median of 4 days (range 3 days to 11 years). 14/18 (77.8%) diagnosed by HRS or NBS had neither clinical manifestations nor radiological features of GA1, or had radiological features only, compared to 0/16 (0%) diagnosed clinically (p < 0.001). Patients diagnosed clinically who survived to school-age were more likely to have significant cerebral palsy and dystonia (7/11; 63.6% vs. 0/13; 0%, p < 0.001). They were less likely to be in mainstream school versus the HRS group (5/10; 50% vs. 12/13; 92.3%; p = 0.012). Clinical events occurring after 6 years of age were unusual, but included spastic diplegia, thalamic haemorrhage, Chiari malformation, pituitary hormone deficiency and epilepsy. The exact aetiology of these events is unclear.

Biochemical and molecular features of Chinese patients with glutaric acidemia type 1 detected through newborn screening

Background

Glutaric acidemia type 1 (GA1) is a treatable disorder affecting cerebral organic acid metabolism caused by a defective glutaryl-CoA dehydrogenase (GCDH) gene. GA1 diagnosis reports following newborn screening (NBS) are scarce in the Chinese population. This study aimed to assess the acylcarnitine profiles and genetic characteristics of patients with GA1 identified through NBS.

Results

From January 2014 to September 2020, 517,484 newborns were screened by tandem mass spectrometry, 102 newborns with elevated glutarylcarnitine (C5DC) levels were called back. Thirteen patients were diagnosed with GA1, including 11 neonatal GA1 and two maternal GA1 patients. The incidence of GA1 in the Quanzhou region was estimated at 1 in 47,044 newborns. The initial NBS results showed that all but one of the patients had moderate to markedly increased C5DC levels. Notably, one neonatal patient with low free carnitine (C0) level suggest primary carnitine deficiency (PCD) but was ultimately diagnosed as GA1. Nine neonatal GA1 patients underwent urinary organic acid analyses: eight had elevated GA and 3HGA levels, and one was reported to be within the normal range. Ten distinct GCDH variants were identified. Eight were previously reported, and two were newly identified. In silico prediction tools and protein modeling analyses suggested that the newly identified variants were potentially pathogenic. The most common variant was c.1244-2 A>C, which had an allelic frequency of 54.55% (12/22), followed by c.1261G>A (p.Ala421Thr) at 9.09% (2/22).

Conclusions

Neonatal GA1 patients with increased C5DC levels can be identified through NBS. Maternal GA1 patients can also be detected using NBS due to the low C0 levels in their infants. Few neonatal GA1 patients may have atypical acylcarnitine profiles that are easy to miss during NBS; therefore, multigene panel testing should be performed in newborns with low C0 levels. This study indicates that the GCDH variant spectra were heterogeneous in this southern Chinese cohort.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13023-021-01964-5.

Evaluation of the Clinical, Biochemical, Neurological, and Genetic Presentations of Glutaric Aciduria Type 1 in Patients From China

Purpose

To characterize the phenotypic and genotypic variations associated with Glutaric aciduria type 1 (GA1) in Chinese patients.

Methods

We analyzed the clinical, neuroradiological, biochemical, and genetic information from 101 GA1 patients in mainland China.

Results

20 patients were diagnosed by newborn screening and the remaining 81 cases were identified following clinical intervention. Macrocephaly was the most common presentation, followed by movement disorders and seizures. A total of 59 patients were evaluated by brain MRI and 58 patients presented with abnormalities, with widening of the sylvian fissures being the most common symptom. The concentration of glutarylcarnitine in the blood, glutarylcarnitine/capryloylcarnitine ratio, and urine levels of glutaric acid were increased in GA1 patients and were shown to decrease following intervention. A total of 88 patient samples were available for genotyping and 74 variants within the GCDH gene, including 23 novel variants, were identified. The most common variant was c.1244-2A > C (18.4%) and there were no significant differences in the biochemical or clinical phenotypes described for patients with the four most common variants: c.1244-2A > C, c.1064G > A, c.533G > A, and c.1147C > T. Patients identified by newborn screening had better outcomes than clinical patients.

Conclusion

Our findings expand the spectrum of phenotypes and genotypes for GA1 in Chinese populations and suggest that an expanded newborn screening program using tandem mass spectrometry may facilitate the early diagnosis and treatment of this disease, improving clinical outcomes for patients in China.

How to detect late-onset inborn errors of metabolism in patients with movement disorders - A modern diagnostic approach

We propose a modern approach to assist clinicians to recognize and diagnose inborn errors of metabolism (IEMs) in adolescents and adults that present with a movement disorder. IEMs presenting in adults are still largely unexplored. These disorders receive little attention in neurological training and daily practice, and are considered complicated by many neurologists. Adult-onset presentations of IEMs differ from childhood-onset phenotypes, which may lead to considerable diagnostic delay. The identification of adult-onset phenotypes at the earliest stage of the disease is important, since early treatment may prevent or lessen further brain damage. Our approach is based on a systematic review of all papers that concerned movement disorders due to an IEM in patients of 16 years or older. Detailed clinical phenotyping is the diagnostic cornerstone of the approach. An underlying IEM should be suspected in particular in patients with more than one movement disorder, or in patients with additional neurological, psychiatric, or systemic manifestations. As IEMs are all genetic disorders, we recommend next-generation sequencing (NGS) as the first diagnostic approach to confirm an IEM. Biochemical tests remain the first choice in acute-onset or treatable IEMs that require rapid diagnosis, or to confirm the metabolic diagnosis after NGS results. With the use of careful and systematic clinical phenotyping combined with novel diagnostic approaches such as NGS, the diagnostic yield of late-onset IEMs will increase, in particular in patients with mild or unusual phenotypes.

Diagnostic Approach to Macrocephaly in Children

Macrocephaly affects up to 5% of the pediatric population and is defined as an abnormally large head with an occipitofrontal circumference (OFC) >2 standard deviations (SD) above the mean for a given age and sex. Taking into account that about 2-3% of the healthy population has an OFC between 2 and 3 SD, macrocephaly is considered as "clinically relevant" when OFC is above 3 SD. This implies the urgent need for a diagnostic workflow to use in the clinical setting to dissect the several causes of increased OFC, from the benign form of familial macrocephaly and the Benign enlargement of subarachnoid spaces (BESS) to many pathological conditions, including genetic disorders. Moreover, macrocephaly should be differentiated by megalencephaly (MEG), which refers exclusively to brain overgrowth, exceeding twice the SD (3SD-"clinically relevant" megalencephaly). While macrocephaly can be isolated and benign or may be the first indication of an underlying congenital, genetic, or acquired disorder, megalencephaly is most likely due to a genetic cause. Apart from the head size evaluation, a detailed family and personal history, neuroimaging, and a careful clinical evaluation are crucial to reach the correct diagnosis. In this review, we seek to underline the clinical aspects of macrocephaly and megalencephaly, emphasizing the main differential diagnosis with a major focus on common genetic disorders. We thus provide a clinico-radiological algorithm to guide pediatricians in the assessment of children with macrocephaly.

The Biennial report: The collaboration between MAGI Research, Diagnosis and Treatment Center of Genetic and Rare Diseases and Near East University DESAM Institute

Background

Scientific collaboration is more common now than it was before. In many areas of biomedical science, collaborations between researchers with different scientific backgrounds and perspectives have enabled researchers to address complicated questions and solve complex problems.

Particularly, international collaborations and improvements in science and technology have shed light on solving the mechanisms that are involved in the etiology of many rare diseases. Hence, the diagnosis and treatment options have been improved for a number of rare diseases. The collaboration between Near East University DESAM Institute and MAGI Research, Diagnosis and Treatment Center of Genetic and Rare Diseases brought out significant results. Importantly, this collaboration contributed to the rare disease research by the identification of novel rare genetic disease-causing variations commonly in pediatric cases. Consequently, many pediatric unsolved cases have been diagnosed.

The main scope of this article is to emphasize the outcomes of the collaboration between Near East University DESAM Institute and MAGI Research, Diagnosis and Treatment Center of Genetic and Rare Diseases which contributed greatly to the scientific literature by identifying novel rare genetic disease-causing variation.