Clinical and mutational spectra of 23 Chinese patients with glutaric aciduria type 1

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.

Recommendations for diagnosing and managing individuals with glutaric aciduria type 1: Third revision

Glutaric aciduria type 1 is a rare inherited neurometabolic disorder of lysine metabolism caused by pathogenic gene variations in GCDH (cytogenic location: 19p13.13), resulting in deficiency of mitochondrial glutaryl-CoA dehydrogenase (GCDH) and, consequently, accumulation of glutaric acid, 3-hydroxyglutaric acid, glutaconic acid and glutarylcarnitine detectable by gas chromatography/mass spectrometry (organic acids) and tandem mass spectrometry (acylcarnitines). Depending on residual GCDH activity, biochemical high and low excreting phenotypes have been defined. Most untreated individuals present with acute onset of striatal damage before age 3 (to 6) years, precipitated by infectious diseases, fever or surgery, resulting in irreversible, mostly dystonic movement disorder with limited life expectancy. In some patients, striatal damage develops insidiously. In recent years, the clinical phenotype has been extended by the finding of extrastriatal abnormalities and cognitive dysfunction, preferably in the high excreter group, as well as chronic kidney failure. Newborn screening is the prerequisite for pre-symptomatic start of metabolic treatment with low lysine diet, carnitine supplementation and intensified emergency treatment during catabolic episodes, which, in combination, have substantially improved neurologic outcome. In contrast, start of treatment after onset of symptoms cannot reverse existing motor dysfunction caused by striatal damage. Dietary treatment can be relaxed after the vulnerable period for striatal damage, that is, age 6 years. However, impact of dietary relaxation on long-term outcomes is still unclear. This third revision of evidence-based recommendations aims to re-evaluate previous recommendations (Boy et al., J Inherit Metab Dis, 2017;40(1):75-101; Kolker et al., J Inherit Metab Dis 2011;34(3):677-694; Kolker et al., J Inherit Metab Dis, 2007;30(1):5-22) and to implement new research findings on the evolving phenotypic diversity as well as the impact of non-interventional variables and treatment quality on clinical outcomes.

Metronidazole-Induced Encephalopathy in a 16-Year-Old Girl with Crohn’s Disease: Case Report and Review of the Pediatric Literature

Metronidazole-induced encephalopathy (MIE) is a rare and unpredictable complication that is most commonly reported in adults. Here, we present the case of MIE in a patient treated with rectal, oral, and intravenous metronidazole. This is the first case of MIE reported after suppositories. A 16-year-old girl with Crohn’s disease treated with mesalazine and exclusive enteral nutrition was operated on due to perianal fistulas and abscesses. She received oral metronidazole for 25 days and rectal metronidazole for 15 days as an adjuvant before surgery. Moreover, 2.5 g of intravenous metronidazole was administrated during the perioperative period. The second day after the surgery, symptoms of cerebellar syndrome appeared. She presented with an inability to coordinate balance and gait. Although she showed accurate verbal responses, her speech was slow, slurred, and scanning. The finger–nose test was positive. The T2-weighted magnetic resonance imaging revealed an increased symmetrical signal within the dentate nuclei of the cerebellum and in the corpus callosum. The changes were characterized by restricted diffusion. Based on the clinical picture and magnetic resonance imaging findings, MIE was diagnosed. Treatment with metronidazole was discontinued. The cumulative dose of metronidazole that she received for 29 days was 54 g: 38 g p.o., 13.5 g p.r., and 2.5 g i,v. The first symptoms appeared on the 28th day of antibiotic therapy after receiving 52 g of metronidazole. The neurological symptoms resolved after six days; however, three days after the resolution, paresthesia appeared in the distal phalanges of both feet and lasted for approximately two months. Our report highlights that neurologic symptoms related to metronidazole treatment should raise the suspicion of MIE.

Does glutaric aciduria type 1 affect hearing function?

This study aimed to evaluate audiological findings among patients with glutaric aciduria type 1 (GA-1). We used a large test battery for the audiological evaluation of 17 individuals with GA-1 (the study group) and 20 healthy individuals (the control group). Conventional audiometry (0.125-8 kHz), distortion product otoacoustic emissions (DPOAEs) (1, 1.5, 2, 3, 4, 6, and 8 kHz), contralateral suppression of otoacoustic emissions, and auditory brainstem response (ABR) ( 30, 50, 70 and 90 dB nHL) were measured for all participants (n = 37). Mild sensorineural hearing loss was found in 77.47% (n = 13) of the patients with GA-1, and normal hearing thresholds were seen in 23.53% (n = 4). There were three asymptomatic patients at the time of diagnosis [two developed mild mental motor retardation (MMR) and one developed severe MMR during the follow-up], one with a normal hearing threshold and two with mild hearing loss), and 14 symptomatic patients (three with normal hearing thresholds and 11 with mild hearing loss). Seven of the symptomatic patients diagnosed following an encephalopathic crisis required intensive care and showed significantly worse hearing thresholds than those without symptoms [20.86 ± 4.47 vs. 15.44 ± 3.96 decibel hearing level (dB HL), p = 0.039*], while five had mild-to-moderate hearing loss. Acute encephalopathic crisis had a negative effect on hearing function in the symptomatic patients. The emission and contralateral suppression amplitude values of the study group were significantly lower compared to the control group (p < 0.05). The I-V interpeak latency and absolute latencies of ABR waves I, III, and V of the study group were observed to be significantly prolonged and morphologically distorted compared to those of the control group (p < 0.05). Five patients had MMR, and three had moderate MMR; all eight had mild-to-moderate hearing loss. In addition, of the eight patients with mild MMR, four had mild hearing loss. In particular, the morphological findings of ABR waves were significantly worse in the patients with severe and moderate MMR (p < 0.05). There was a significant correlation between a macrocephaly history (12 patients) and hearing loss (p = 0.041*). Magnetic resonance imaging findings were evaluated in all the 17 patients with GA-1, and typical fronto-temporal atrophy and sylvian fissure enlargement were observed. Our findings support that GA-1 is associated with auditory impairment, primarily in symptomatic patients. Adequate audiological test battery evaluation is essential in this context, particularly for symptomatic patients with a history of encephalopathic crises.

Identification of novel pathogenic variants in the GCDH gene and assessment of neurodevelopmental outcomes in 24 children with glutaric aciduria type 1

AIM

To evaluate the pathogenic variants in GCDH gene and to assess the neurodevelopmental outcomes in children with Glutaric aciduria type 1 (GA-1).

METHOD

Cross-sectional observational study between January 2019 and June 2020 in consecutive North Indian children with a clinical and biochemical suspicion of GA-1. Variants in the coding regions of GCDH gene were identified through Sanger sequencing. Neurodevelopmental and quality of life assessment was done using standardized scales.

RESULTS

24 children with GA-1 were identified. The median age at diagnosis was 12 months and the median delay in diagnosis was 3 months. Genetic analysis was done in 14 cases. It revealed 12 variants (11 missense and one nonsense) from 13 patients. Most of the pathogenic variants were in exon 9 and exon 5. Three novel variants were identified in three patients: two missense variants c.169G > A (p.Glu57Lys), c.1048T > C (p.Cys350Arg) and one nonsense variant c.331C > T (p.Lys111Ter). On neurodevelopmental assessment, majority of children with GA-1 were non ambulatory (62.5%), had limited hand skills (58.3%) and impaired communication (58.3%). Overall, poor global development was noted in 43.7%. A pre-existing developmental delay was significantly associated with impaired communication skills (p = 0.03), and the number of episodes of encephalopathy were significantly associated with impaired gross motor skill (p = 0.02). Presence of encephalopathy was significantly associated with poor performance in social emotional (p = 0.01) and cognitive (p = 0.03) domains of Developmental Profile-III scale and development of severe dystonia (p = 0.01).

CONCLUSION

Our findings highlight the clinical, biochemical, radiological and genetic spectrum of GA-1 in children in North India and report the presence of novel pathogenic variations.

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.

Rhabdomyolysis, Acute Kidney Injury, and a Novel Frameshift Mutation in a Child with Glutaric Acidemia Type I

This is a case report of a girl with glutaric acidemia type I (GA-I) who experienced rhabdomyolysis and acute kidney injury (AKI). Her first acute metabolic crisis occurred at the age of 5 months, which mainly manifested as irritable crying, poor appetite, and hyperlactatemia. Mutation analysis showed 2 pathogenic mutations in the glutaryl-CoA dehydrogenase (GCDH) gene, which were c.383G>A (p.R128Q) and c.873delC (p.N291Kfs*41), the latter of which is a novel frameshift mutation of GA-I. She had a febrile illness at the age of 12 months, followed by AKI and severe rhabdomyolysis. Four days of continuous venovenous hemodiafiltration (CVVHDF) helped to overcome this acute decompensation. This case report describes a novel mutation in the GCDH gene, that is, c.873delC (p.N291Kfs*41). Also, it highlights the fact that patients with GA-I have a high risk of rhabdomyolysis and AKI, which may be induced by febrile diseases and hyperosmotic dehydration; CVVHDF can help to overcome this acute decompensation.

Metabolic Serendipities of Expanded Newborn Screening

Incidental findings on newborn screening (NBS) are results that are not the target of screening within a given NBS program, but rather are found as a result of the screening and resulting diagnostic workup for that target. These findings may not have an immediate clinical impact on the newborn, but are sometimes an additional benefit of NBS programs and may be considered secondary targets of NBS programs. This work describes four case reports that had incidental findings on the NBS, which eventually led to the diagnosis of another metabolic disease instead of the one that was initially suspected. The first case was a new defect in the cationic amino acid transporter-2 (CAT-2), which was oriented as an arginase-1 deficiency in the newborn. The second case was a maternal glutaric aciduria type 1 (GA-1) that mimicked a carnitine transporter deficiency in the newborn. The third report was a case of lysinuric protein intolerance (LPI), which appeared as high levels of citrulline on the NBS. The fourth case was a mother with homocystinuria that was diagnosed during the biochemical study of vitamin B₁₂ status. All cases provide new or interesting data that will help guide differential diagnosis in the future.

Glutaric aciduria type 1: Genetic and phenotypic spectrum in 53 patients

INTRODUCTION

Glutaric aciduria type 1 (GA1) is a rare and inherited autosomal-recessive metabolic disorder that occurs in the deficiency of glutaryl-co-enzyme A dehydrogenase (GCDH) enzyme encoded by GCDH gene. In this study, we aim to retrospectively investigate the clinical, biochemical, and neuroradiological parameters and examine the spectrum of GCDH gene variants in Turkish patients with glutaric aciduria type 1.

METHODS

This is a descriptive cross-sectional study. The study was conducted in fifty-three patients from 39 unrelated Turkish families who were diagnosed with GA1 based on their clinical presentation, neuroimaging, and biochemical measurements, at the department of pediatric metabolism of a university hospital between June 1998 and August 2019. Pathogenic variants screening of GCDH gene was performed by direct DNA sequence analysis in forty-six patients with GA1. Pathogenicity of the novel variants was predicted via computational programs.

RESULTS

A total of 53 patients were diagnosed with GA1. Of those, 32 (60.3%) had encephalopathic crisis and 33 (62.3%) had macrocephaly. Twenty different pathogenic variants were detected, 7 of which are novel (p.Glu57Lys, p.Ser145Profs*79, p.Ser246Glyfs*96 p.Ala293Val, p.His348Gln, p.His417Tyr, p.Asp418Val). The p.Arg402Trp, p.Pro248Leu and p.Leu340Phe variants were the most common in Turkish patients, with a frequency of 21.2%, 18.2% and 12.1% respectively.

CONCLUSION

This study is the first comprehensive research from Turkey that provides information about disease-causing variants in the GCDH gene. The identification of common variants and hot spot regions of the GCDH gene is important for genetic counselling and the prenatal diagnosis of Turkish patients with GA1.

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

Glutaric aciduria type I (GA1; OMIM #231670) is an autosomal recessively inherited and treatable disorder characterized by the accumulation and irregular excretion of glutaric acid due to a defect in the glutaryl-CoA dehydrogenase enzyme involved in the catabolic pathways of L-lysine, L-hydroxylysine, and L-tryptophan. Glutaryl-CoA dehydrogenase is encoded by the GCDH gene (OMIM #608801), and several mutations in this gene are known to result in GA1. GA1 usually presents in the first 18-36 months of life with mild or severe acute encephalopathy, movement disorders, and striatal degeneration. Few cases of adult-onset GA1 have been described so far in the literature, often with non-specific and sometimes longstanding neurological symptoms. Since a preventive metabolic treatment is available, neurologists must be aware of this rare but likely underdiagnosed presentation, especially when typical neuroimaging features are identified. Here, we describe 35-year-old presenting with headache and subjective memory problems. There was no history of dystonic movement disorders. Neurological examination and neurocognitive tests were normal. Brain MRI scan revealed white matter abnormalities associated with subependymal nodules and mild frontotemporal hypoplasia suggestive of glutaric aciduria type 1 (GA1). Genetic testing confirmed the presence of homozygous c.1204C > T (p.R402W) variant in the GCDH gene, inherited from heterozygous parents.

Prenatal diagnosis of fetal glutaric aciduria type 1 with rare compound heterozygous mutations in GCDH gene

OBJECTIVE

Glutaric aciduria type 1 is a rare disease, with the estimated prevalence about 1 in 100,000 newborns. GCDH gene mutation can lead to glutaric acid and 3- OH glutaric acid accumulation, with clinical manifestation of neuronal damage, brain atrophy, microencephalic macrocephaly, decreased coordination of swallowing, poor muscle coordination, spasticity, and severe dystonic movement disorder.

CASE REPORT

A 22-year-old female, Gravida 4 Para 2, is pregnancy at 13 weeks of gestational age. Her first child is normal, however, the second child was diagnosed as glutaric aciduria type I after birth. She came to our hospital for prenatal genetic counselling of her fetus at 13 weeks of gestational age. We performed GCDH gene mutation analysis of maternal blood showed IVS 3 + 1 G > A heterozygous mutation, GCDH gene mutation analysis of paternal blood showed c. 1240 G > A heterozygous mutation, and the second child has compound heterozygous IVS 3 + 1 G > A and c. 1240 G > A mutations. Later, we performed amniocentesis at 16 weeks of gestational age for chromosome study and GCDH gene mutation analysis for the fetus. The fetal chromosome study showed normal karyotype, however, GCDH gene mutation analysis showed compound heterozygous IVS 3 + 1 G > A and c. 1240 G > A mutations. The couple decided to termination of pregnancy thereafter.

CONCLUSION

Glutaric acidemia type 1 is an autosomal recessive disorder because of pathogenic mutations in the GCDH gene. Early diagnosis and therapy of glutaric acidemia type 1 can reduce the risk of neuronal damage and acute dystonia. We report a case of prenatal diagnosis of fetal glutaric aciduria type 1 with rare compound heterozygous GCDH gene mutation at IVS 3 + 1 G > A and c. 1240 G > A mutations, which provide better genetic counselling for the couples.

Two Uneventful Pregnancies in a Woman with Glutaric Aciduria Type 1

Glutaric aciduria type 1 (GA1) is an autosomal recessive rare disorder caused by mutations in the GCDH gene resulting in deficiency of glutaryl-CoA dehydrogenase, leading to accumulation of the amino acids lysine, hydroxylysine and tryptophan and other metabolites. The phenotypic spectrum of disease is broad. Stress caused by infection and fever and possibly pregnancy may lead to worsening of the signs and symptoms, often with uncertain recovery.We describe a case of a female patient with GA1 who had two clinically uneventful pregnancies.At the age of 11 she was diagnosed with GA1 by family screening. The cultured skin fibroblast showed reduced glutaryl-CoA dehydrogenase activity (0.16 mg protein per min).The initial diagnostic urine glutaric acid level for this patient was 1,784 μmol/mmol creatinine. Mutation analysis showed compound heterozygosity for the p.(Gly185Arg), c.553G>A in exon 7 and p.(Arg402Trp), c.1204C.T in exon 11 mutations of the GCDH.Her pregnancy at the age of 23 was complicated by pre-eclampsia and required treatment with beta-blockers. Four years later the second pregnancy was uncomplicated. The management plan during the caesarean section included intravenous dextrose and lipid infusions. The patient rapidly recovered from both surgeries.Both babies have had normal development to date. On newborn screening, plasma acylcarnitine showed a transient increase in glutarylcarnitine, and the urine organic acid analysis showed a trace of 3-hydroxyglutarylcarnitine, likely to be of maternal transfer.The multidisciplinary team, consisting of metabolic, dietetic and obstetric care providers, have responsibility to ensure the risk of acute decompensation in pregnant GA1 women is minimal.

Genotype-phenotype correlation in 18 Egyptian patients with glutaric acidemia type I

Glutaric acidemia I (GAI) is an autosomal recessive metabolic disease caused by a deficiency of glutaryl-CoA dehydrogenase enzyme (GCDH). Patients with GAI are characterized by macrocephaly, acute encephalitis-like crises, dystonia and frontotemporal atrophy. In this study, we investigated 18 Egyptian patients that were diagnosed with GAI based on their clinical, neuroradiological, and biochemical profiles. Of the 18 patients, 16 had developmental delay and/or regression, dystonia was prominent in 75% of the cases, and three patients died. Molecular genetics analysis identified 14 different mutations in the GCDH gene in the 18 patients, of the 14 mutations, nine were missense, three were in the 3'-Untranslated Region (3'-UTR), one was nonsense, and one was a silent mutation. Four novel mutations were identified (c.148 T > A; p.Trp50Arg, c.158C > A; p.Pro53Gln, c.1284C > G; p.Ile428Met, and c.1189G > T; p.Glu397*) that were all absent in 300 normal chromosomes. The 3'-UTR mutation (c.*165A > G; rs8012), was the most frequent mutation observed (0.5; 18/36), followed by the most common mutation among Caucasian patients (p.Arg402Trp; rs121434369) with allele frequency of 0.36 (13/36), and the 3'-UTR mutation (c.*288G > T; rs9384, 0.22; 8/16). The p.Arg257Gln mutation was found with allele frequency of ~0.17 (6/36). The marked homozygosity observed in our patients is probably due to the high level of consanguinity that is observed in 100% of the cases. We used nine in silico prediction tools to predict the pathogenicity (SIFT, PhD-SNP, SNAP, Meta-SNP, PolyPhen2, and Align GVGD) and protein stability (I-Mutant2.0, Mupro, and istable) of the nine missense mutants. The mutant p.Arg402Trp was predicted to be most deleterious by all the six pathogenicity prediction tools and destabilizing by all the three-stability prediction tools, and highly conserved by the ConSurf server. Using the clinical, biochemical, family history of the 18 patients, and the in silico analysis of the missense mutations, our study showed a mix of conclusive and inconclusive genotype-phenotype correlations among our patient's cohort and suggests the usefulness of using various sophisticated computational analysis to be utilized for future variant classifications in the genetic clinics.

Disease-causing mutations affecting surface residues of mitochondrial glutaryl-CoA dehydrogenase impair stability, heteromeric complex formation and mitochondria architecture

The neurometabolic disorder glutaric aciduria type 1 (GA1) is caused by mutations in the GCDH gene encoding the mitochondrial matrix protein glutaryl-CoA dehydrogenase (GCDH), which forms homo- and heteromeric complexes. Twenty percent of all pathogenic mutations affect single amino acid residues on the surface of GCDH resulting in a severe clinical phenotype. We report here on heterologous expression studies of 18 missense mutations identified in GA1 patients affecting surface amino acids. Western blot and pulse chase experiments revealed that the stability of half of the GCDH mutants was significantly reduced. In silico analyses showed that none of the mutations impaired the 3D structure of GCDH. Immunofluorescence co-localisation studies in HeLa cells demonstrated that all GCDH mutants were correctly translocated into mitochondria. Surprisingly, the expression of p.Arg88Cys GCDH as well as further substitutions by alanine, lysine, or methionine but not histidine or leucine resulted in the disruption of mitochondrial architecture forming longitudinal structures composed of stacks of cristae and partial loss of the outer mitochondrial membrane. The expression of mitochondrial fusion or fission proteins was not affected in these cells. Bioluminescence resonance energy transfer analyses revealed that all GCDH mutants exhibit an increased binding affinity to electron transfer flavoprotein beta, whereas only p.Tyr155His GCDH showed a reduced interaction with dihydrolipoamide succinyl transferase. Our data underscore the impact of GCDH protein interactions mediated by amino acid residues on the surface of GCDH required for proper enzymatic activity.

[Effect of glutaryl-CoA dehydrogenase gene silencing and high-concentration lysine on the viability of BRL hepatocytes]

OBJECTIVE

To investigate the effect of glutaryl-CoA dehydrogenase (GCDH) gene silencing and accumulation of lysine metabolites on the viability of hepatocytes.

METHODS

BRL cells were divided into normal control group, negative control group, and GCDH silencing group. The shRNA lentiviral vector for silencing GCDH gene was constructed, and the BRL hepatocytes in the GCDH silencing group and the negative control group were infected with this lentivirus and negative control virus respectively, and then cultured in a medium containing 5 mmol/L lysine. Immunofluorescence assay was used to measure the infection efficiency of lentivirus. Western blot was used to measure the expression of GCDH protein. MTT assay was used to evaluate cell viability. Hoechest33342 staining was used to measure cell apoptosis. Western blot was used to measure the expression of Caspase-3, an index of cell apoptosis.

RESULTS

The lentivirus constructed effectively silenced the GCDH gene in hepatocytes (P<0.01). MTT assay and Hoechest 33342 staining showed no significant differences in cell viability and apoptosis between groups (P>0.05). There was also no significant difference in the expression of Caspase-3 protein between groups (P>0.05).

CONCLUSIONS

GCDH gene silencing and accumulation of lysine metabolites may not cause marked hepatocyte injury.

Dentate Update: Imaging Features of Entities That Affect the Dentate Nucleus

The dentate nucleus is a cerebellar structure involved in voluntary motor function and cognition. There are relatively few entities that affect the dentate, and the clinical features of these conditions are often complex and nonspecific. Because these entities are rarely encountered, the formulation of a differential diagnosis can be difficult. Many of the conditions are reversible or treatable with early intervention. Therefore, it is important to recognize classic clinical presentations and their associated characteristic imaging findings. We provide a summary of entities that affect the dentate nucleus and a diagnostic workflow for approaching dentate nucleus imaging abnormalities.

Glutaric Acidemia Type 1: A Case of Infantile Stroke

BACKGROUND

Glutaric acidemia Type 1 (GA-1) is an autosomal recessively inherited metabolic disorder which is associated with GCDH gene mutations which alters the glutaryl-CoA dehydrogenase, an enzyme playing role in the catabolic pathways of the amino acids lysine, hydroxylysine, and tryptophan. Clinical findings are often encephalopathic crises, dystonia, and extrapyramidal symptoms.

CASE REPORT

A 9-month-old male infant referred to our department with focal tonic-clonic seizures during rotavirus infection and acute infarcts in MRI. Clinical manifestation, MRI findings, and metabolic investigations directed thoughts towards GA-I. Molecular genetic testing revealed a homozygous c.572T>C (p.M191T) mutation in GCDH gene which confirmed the diagnosis. Application of protein restricted diet, carnitine and riboflavin supplementations prevented the progression of Magnetic Resonance Imaging (MRI) and clinical pathologic findings during the 1 year of follow-up period.

CONCLUSION

This case is of great importance since it shows possibility of infantile stroke in GA-1, significance of early diagnosis and phenotypic variability of disease.

Proposed recommendations for diagnosing and managing individuals with glutaric aciduria type I: second revision

Glutaric aciduria type I (GA-I; synonym, glutaric acidemia type I) is a rare inherited metabolic disease caused by deficiency of glutaryl-CoA dehydrogenase located in the catabolic pathways of L-lysine, L-hydroxylysine, and L-tryptophan. The enzymatic defect results in elevated concentrations of glutaric acid, 3-hydroxyglutaric acid, glutaconic acid, and glutaryl carnitine in body tissues, which can be reliably detected by gas chromatography/mass spectrometry (organic acids) and tandem mass spectrometry (acylcarnitines). Most untreated individuals with GA-I experience acute encephalopathic crises during the first 6 years of life that are triggered by infectious diseases, febrile reaction to vaccinations, and surgery. These crises result in striatal injury and consequent dystonic movement disorder; thus, significant mortality and morbidity results. In some patients, neurologic disease may also develop without clinically apparent crises at any age. Neonatal screening for GA-I us being used in a growing number of countries worldwide and is cost effective. Metabolic treatment, consisting of low lysine diet, carnitine supplementation, and intensified emergency treatment during catabolism, is effective treatment and improves neurologic outcome in those individuals diagnosed early; treatment after symptom onset, however, is less effective. Dietary treatment is relaxed after age 6 years and should be supervised by specialized metabolic centers. The major aim of this second revision of proposed recommendations is to re-evaluate the previous recommendations (Kölker et al. J Inherit Metab Dis 30:5-22, 2007b; J Inherit Metab Dis 34:677-694, 2011) and add new research findings, relevant clinical aspects, and the perspective of affected individuals.

Clinical and laboratory analysis of late-onset glutaric aciduria type I (GA-I) in Uighur: A report of two cases

The aim of the present study was to investigate the clinical, biochemical and genetic mutation characteristics of two cases of late-onset glutaric aciduria type I (GA-I) in Uighur. The clinical data and glutaryl-CoA dehydrogenase (GCDH) genetic test results of two cases of late-onset GA-I in Uighur were collected and analyzed, and reviewed with relevant literature. One patient with late-onset GA-I primarily exhibited clinical intermittent headache, while the other patient was asymptomatic. The urinary organic acid analysis detected a large number of glutaric acid and 3-hydroxy glutaric acid, 3-hydroxy-propionic acid. One patient exhibited white matter degeneration in cranial magnetic resonance imaging (MRI) and the other patient showed no abnormality. The two patients both exhibited c. 1204C >T, p.R402W, heterozygous mutation, and c. 532G >A, p.G178R, heterozygous mutation. Besides central nervous system infectious diseases, patients with clinical headache, cranial MRI-suggested bilateral temporal lobe arachnoid cyst and abnormal signals in the basal ganglia should be highly suspected as late-onset GA-I. Early diagnosis and correct treatment are key to improve its prognosis.

Recurrent rhabdomyolysis and glutaric aciduria type I: a case report and literature review

BACKGROUND

Glutaric acidemia type I (GA-I) is a rare metabolic disorder caused by mutation of the glutaryl- CoA dehydrogenase (GCDH) gene. The occurrence of rhabdomyolysis with GA-I is extremely rare.

METHODS

We reported a child with recurrent rhabdomyolysis and undiagnosed glutaric acidemia type I (GA-I). And a literature review was performed.

RESULTS

A 4.5-year-old girl was admitted to our hospital due to recurrent rhabdomyolysis for 3 times within three years. At the third admission, she was diagnosed with GA-I by biochemical testing and mutation analysis. The girl was found to have a serine to leucine replacement mutation of the GCDH gene in exon 8 at position 764. Other three patients with rhabdomyolysis and GA-I were discovered by literature searching.

CONCLUSIONS

This report highlights that patients with GA-I may have an increased risk of rhabdomyolysis.

[Limb torsion and developmental regression for one month after hand, foot and mouth disease in an infant]

A one-year-old girl visited the hospital due to limb torsion and developmental regression for one month after hand, foot and mouth disease. At the age of 11 months, she visited a local hospital due to fever for 5 days and skin rash with frequent convulsions for 2 days and was diagnosed with severe hand, foot and mouth disease, viral encephalitis, and status epilepticus. Brain MRI revealed symmetric abnormal signals in the bilateral basal ganglia, bilateral thalamus, cerebral peduncle, bilateral cortex, and hippocampus. She was given immunoglobulin, antiviral drugs, and anticonvulsant drugs for 2 weeks, and the effect was poor. Blood and urine screening for inherited metabolic diseases were performed to clarify the etiology. The analysis of urine organic acids showed significant increases in glutaric acid and 3-hydroxyglutaric acid, which suggested glutaric aciduria type 1, but her blood glutarylcarnitine was normal, and free carnitine significantly decreased. After the treatment with low-lysine diets, L-carnitine, and baclofen for 1 month, the patient showed a significant improvement in symptoms. Hand, foot and mouth disease is a common viral infectious disease in children, and children with underlying diseases such as inherited metabolic diseases and immunodeficiency may experience serious complications. For children with hand, foot and mouth disease and unexplained encephalopathy, inherited metabolic diseases should be considered.

[Complex heterogeneity phenotypes and genotypes of glutaric aciduria type 1]

Glutaric aciduria type 1 is a rare autosomal recessive disorder. GCDH gene mutations cause glutaryl-CoA dehydrogenase deficiency and accumulation of glutaric acid and 3-hydroxyglutaric acid, resulting in damage of striatum and other brain nucleus and neurodegeneration. Patients with glutaric aciduria type 1 present with complex heterogeneous phenotypes and genotypes. The symptoms are extremely variable. The ages of the clinical onset of the patients range from the fetus period to adulthood. The patients with mild glutaric aciduria type 1 are almost asymptomatic before onset, however, severe glutaric aciduria type 1 may cause death or disability due to acute encephalopathy. Acute metabolic crisis in patients with underlying glutaric aciduria type 1 is often triggered by febrile illnesses, trauma, hunger, high-protein foods and vaccination during a vulnerable period of brain development in infancy or early childhood. The early-onset patients usually have a poor prognosis. Urinary organic acids analysis, blood acylcarnitines analysis and GCDH study are important for the diagnosis of this disorder. Neonatal screening is essential for the early diagnosis and the improvement of prognosis.

Liquid-Liquid Extraction and Solid Phase Extraction for Urinary Organic Acids: A Comparative Study from a Resource Constraint Setting

Pre analytical process of extraction for accurate detection of organic acids is a crucial step in diagnosis of organic acidemias by GCMS analysis. This process is accomplished either by solid phase extraction (SPE) or by liquid-liquid extraction (LLE). Both extraction procedures are used in different metabolic laboratories all over the world. In this study we compared these two extraction procedures in respect of precision, accuracy, percent recovery of metabolites, number of metabolites isolated, time and cost in a resource constraint setup. We observed that the mean recovery from SPE was 84.1 % and by LLE it was 77.4 % (p value <0.05). Moreover, the average number of metabolites isolated by SPE and LLE was 161.8 ± 18.6 and 140.1 ± 20.4 respectively. The processing cost of LLE was economical. In a cost constraint setting using LLE may be the practical option if used for organic acid analysis.

Clinical and molecular investigation in Chinese patients with glutaric aciduria type I

Glutaric aciduria type I (GA-I) is a rare autosomal recessive metabolic disorder caused by deficiency of glutaryl-CoA dehydrogenase (GCDH), leading to an abnormal metabolism of lysine, hydroxylysine and tryptophan. It results in accumulations of glutaric acid, 3-hydroxyglutaric acid and glutaconic acid. Clinical features include the sudden onset of encephalopathy, hypotonia and macrocephaly usually before age 18months. Here we report five cases of GA-I confirmed with mutation analysis. GCDH gene mutations were identified in all five probands with GA-I. Three of them had compound heterozygous mutations and two had homozygous mutations. Mutations of two alleles (c.334G>T and IVS11-11A>G) were novel and both of them were confirmed to be splice site mutations by reverse transcription PCR.

Glutaric aciduria type 1 as a cause of dystonic cerebral palsy

Glutaric aciduria type 1 (GA1) is an inherited inborn error of metabolism caused by a deficiency of the enzyme glutaryl Co-A dehydrogenase (GCDH). Here, we report a 14-month-old Saudi boy with GA1 who presented with severe dystonia and was mis-diagnosed as cerebral palsy (CP). He presented to our institute with encephalopathy following an episode of gastroenteritis. His physical examination showed dystonia and spastic quadriplegia. His investigations revealed elevated both urinary 3-hydroxy glutaric acid, and serum glutarylcarnitine. The DNA analysis confirmed homozygosity for a mutation in the GCDH-coding gene (c.482G>A;p.R161Q). This case alerts pediatricians to consider GA1 as a differential diagnosis of children presenting with dystonic CP.