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Journal of Pharmaceutical and... Jan 2024Orotic aciduria is a severe, hereditary, life-threatening condition, particularly in newborns. An increased orotic acid (OA) content in urine may be a strong indicator... (Review)
Review
Highly sensitive rapid determination of orotic acid in urine samples using a field-amplified sample stacking approach in capillary electrophoresis coupled with contactless conductivity detection.
Orotic aciduria is a severe, hereditary, life-threatening condition, particularly in newborns. An increased orotic acid (OA) content in urine may be a strong indicator of this condition. In this study, we developed a rapid, simple, highly sensitive diagnostic method for use in monitoring the OA levels in urine samples, which were successfully determined using capillary electrophoresis combined with capacitively coupled contactless conductivity detection (CE-CD). A straightforward analysis with an increased sensitivity towards OA and an analysis time of approximately 5 min were realized, and the limit of detection of the developed method was 0.014 mg/L in aqueous solution. The optimized composition of the separation electrolyte was 20 mM 2-(N-morpholino)ethanesulfonic acid/histidine with 0.1 mM cetyltrimethylammonium bromide at a pH of 6.5. The sensitivity of the developed method was significantly increased using a sample stacking approach with a 10% acetonitrile (v/v) plug solution. The method was validated, and satisfactory recoveries of 80.0-92.3% were obtained. The amounts of OA in five urine samples were successfully determined.
Topics: Infant, Newborn; Humans; Orotic Acid; Electrophoresis, Capillary; Water; Electric Conductivity; Electrolytes
PubMed: 37922673
DOI: 10.1016/j.jpba.2023.115826 -
Clinical Chemistry and Laboratory... Feb 2024Acylcarnitine and amino acid analyses of dried blood spot (DBS) samples using tandem mass spectrometry in newborn screening (NBS) programmes can generate false positive...
OBJECTIVES
Acylcarnitine and amino acid analyses of dried blood spot (DBS) samples using tandem mass spectrometry in newborn screening (NBS) programmes can generate false positive (FP) results. Therefore, implementation of second-tier tests (2TTs) using DBS samples has become increasingly important to avoid FPs. The most widely used 2TT metabolites include methylmalonic acid, 3-hydroxypropionic acid, methylcitric acid, and homocysteine.
METHODS
We simultaneously measured 46 underivatised metabolites, including organic acids, acylglycine and acylcarnitine isomers, homocysteine, and orotic acid, in DBS samples using tandem mass spectrometry. To validate this method, we analysed samples from 147 healthy newborns, 160 patients with genetic disorders diagnosed via NBS, 20 patients with acquired vitamin B12 deficiency, 10 newborns receiving antibiotic treatment, and nine external quality control samples.
RESULTS
The validation study revealed that 31 metabolites showed good analytical performance. Furthermore, this method detected key metabolites for all diseases associated with increased levels of the following acylcarnitines: C3, C4, C5, C4DC/C5OH, and C5DC. The sensitivity of this method to detect all diseases was 100 %, and the specificity was 74-99 %, except for glutaric aciduria type 1. This method can also be used to diagnose mitochondrial fatty acid β-oxidation disorders (FAODs) and urea cycle defects (UCDs).
CONCLUSIONS
We have described a 2TT panel of 31 metabolites in DBS samples based on an easy and rapid method without derivatisation. Its implementation allowed us to distinguish between different organic acidurias, some FAODs, and UCDs. This new strategy has increased the efficiency of our NBS programme by reducing FP and false negative results, second sample requests, and the time required for diagnosis.
Topics: Humans; Infant, Newborn; Tandem Mass Spectrometry; Neonatal Screening; Spain; Chromatography, Liquid; Homocysteine; Dried Blood Spot Testing; Amino Acid Metabolism, Inborn Errors; Brain Diseases, Metabolic; Carnitine; Glutaryl-CoA Dehydrogenase
PubMed: 37794778
DOI: 10.1515/cclm-2023-0216 -
Human Gene Therapy Sep 2023Realization of the immense therapeutic potential of epigenetic editing requires development of clinically predictive model systems that faithfully recapitulate relevant...
Recapitulation of Skewed X-Inactivation in Female Ornithine Transcarbamylase-Deficient Primary Human Hepatocytes in the FRG Mouse: A Novel System for Developing Epigenetic Therapies.
Realization of the immense therapeutic potential of epigenetic editing requires development of clinically predictive model systems that faithfully recapitulate relevant aspects of the target disease pathophysiology. In female patients with ornithine transcarbamylase (OTC) deficiency, an X-linked condition, skewed inactivation of the X chromosome carrying the wild-type OTC allele is associated with increased disease severity. The majority of affected female patients can be managed medically, but a proportion require liver transplantation. With rapid development of epigenetic editing technology, reactivation of silenced wild-type OTC alleles is becoming an increasingly plausible therapeutic approach. Toward this end, privileged access to explanted diseased livers from two affected female infants provided the opportunity to explore whether engraftment and expansion of dissociated patient-derived hepatocytes in the FRG mouse might produce a relevant model for evaluation of epigenetic interventions. Hepatocytes from both infants were successfully used to generate chimeric mouse-human livers, in which clusters of primary human hepatocytes were either OTC positive or negative by immunohistochemistry (IHC), consistent with clonal expansion from individual hepatocytes in which the mutant or wild-type OTC allele was inactivated, respectively. Enumeration of the proportion of OTC-positive or -negative human hepatocyte clusters was consistent with dramatic skewing in one infant and minimal to modest skewing in the other. Importantly, IHC and fluorescence-activated cell sorting analysis of intact and dissociated liver samples from both infants showed qualitatively similar patterns, confirming that the chimeric mouse-human liver model recapitulated the native state in each infant. Also of importance was the induction of a treatable metabolic phenotype, orotic aciduria, in mice, which correlated with the presence of clonally expanded OTC-negative primary human hepatocytes. We are currently using this unique model to explore CRISPR-dCas9-based epigenetic targeting strategies in combination with efficient adeno-associated virus (AAV) gene delivery to reactivate the silenced functional OTC gene on the inactive X chromosome.
Topics: Infant; Humans; Mice; Female; Animals; Ornithine Carbamoyltransferase; X Chromosome Inactivation; Hepatocytes; Liver; Ornithine Carbamoyltransferase Deficiency Disease
PubMed: 37350098
DOI: 10.1089/hum.2023.011 -
Frontiers in Genetics 2023Hereditary orotic aciduria is an extremely rare, autosomal recessive disease caused by deficiency of uridine monophosphate synthase. Untreated, affected individuals may...
Hereditary orotic aciduria is an extremely rare, autosomal recessive disease caused by deficiency of uridine monophosphate synthase. Untreated, affected individuals may develop refractory megaloblastic anemia, neurodevelopmental disabilities, and crystalluria. Newborn screening has the potential to identify and enable treatment of affected individuals before they become significantly ill. Measuring orotic acid as part of expanded newborn screening using flow injection analysis tandem mass spectrometry. Since the addition of orotic acid measurement to the Israeli routine newborn screening program, 1,492,439 neonates have been screened. The screen has identified ten Muslim Arab newborns that remain asymptomatic so far, with DBS orotic acid elevated up to 10 times the upper reference limit. Urine organic acid testing confirmed the presence of orotic aciduria along with homozygous variations in the gene. Newborn screening measuring of orotic acid, now integrated into the routine tandem mass spectrometry panel, is capable of identifying neonates with hereditary orotic aciduria.
PubMed: 36999056
DOI: 10.3389/fgene.2023.1135267 -
International Journal of Developmental... Dec 2022Urea cycle disorders (UCD) are a group of genetic diseases caused by deficiencies in the enzymes and transporters involved in the urea cycle. The impairment of the cycle...
Urea cycle disorders (UCD) are a group of genetic diseases caused by deficiencies in the enzymes and transporters involved in the urea cycle. The impairment of the cycle results in ammonia accumulation, leading to neurological dysfunctions and poor outcomes to affected patients. The aim of this study is to investigate and describe UCD patients' principal clinical and biochemical presentations to support professionals on urgent diagnosis and quick management, aiming better outcomes for patients. We explored medical records of 30 patients diagnosed in a referral center from Brazil to delineate UCD clinical and biochemical profile. Patients demonstrated a range of signs and symptoms, such as altered levels of consciousness, acute encephalopathy, seizures, progressive loss of appetite, vomiting, coma, and respiratory distress, in most cases combined with high levels of ammonia, which is an immediate biomarker, leading to a UCD suspicion. The most prevalent UCD detected were ornithine transcarbamylase deficiency, followed by citrullinemia type 1, hyperargininemia, carbamoyl phosphate synthase 1 deficiency, and argininosuccinic aciduria. Clinical symptoms were highly severe, being the majority developmental and neurological disabilities, with 20% of death rate. Laboratory analysis revealed high levels of ammonia (mean ± SD: 860 ± 470 μmol/L; reference value: ≤80 μmol/L), hypoglycemia, metabolic acidosis, and high excretion of orotic acid in the urine (except in carbamoyl phosphate synthetase 1 [CPS1] deficiency). We emphasize the need of urgent identification of UCD clinical and biochemical conditions, and immediate measurement of ammonia, to enable the correct diagnosis and increase the chances of patients' survival, minimizing neurological and psychomotor damage caused by hepatic encephalopathy.
Topics: Humans; Hyperammonemia; Hepatic Encephalopathy; Ammonia; Urea Cycle Disorders, Inborn; Ornithine Carbamoyltransferase Deficiency Disease
PubMed: 36129623
DOI: 10.1002/jdn.10229 -
JIMD Reports Sep 2022N-acetylglutamate synthase (NAGS) deficiency is a rare autosomal recessive disorder, which results in the inability to activate the key urea cycle enzyme,...
N-acetylglutamate synthase (NAGS) deficiency is a rare autosomal recessive disorder, which results in the inability to activate the key urea cycle enzyme, carbamoylphosphate synthetase 1 (CPS1). Patients often suffer life-threatening episodes of hyperammonaemia, both in the neonatal period and also at subsequent times of catabolic stress. Because NAGS generates the cofactor for CPS1, these two disorders are difficult to distinguish biochemically. However, there have now been numerous case reports of 3-methylglutaconic aciduria (3-MGA), a marker seen in mitochondrial disorders, occurring in CPS1 deficiency. Previously, this had not been reported in NAGS deficiency. We report a four-day-old neonate who was noted to have 3-MGA at the time of significant hyperammonaemia and lactic acidosis. Low plasma citrulline and borderline orotic aciduria were additional findings that suggested a proximal urea cycle disorder. Subsequent molecular testing identified bi-allelic pathogenic variants in . The 3-MGA was present at the time of persistent lactic acidosis, but improved with normalization of serum lactate, suggesting that it may reflect secondary mitochondrial dysfunction. NAGS deficiency should therefore also be considered in patients with hyperammonaemia and 3-MGA. Studies in larger numbers of patients are required to determine whether it could be a biomarker for severe decompensations.
PubMed: 36101823
DOI: 10.1002/jmd2.12318 -
Frontiers in Immunology 2022The hyperornithinemia-hyperammonemia-homocitrullinuria (HHH) syndrome is a rare autosomal recessive inborn error of the urea cycle caused by mutations in the gene....
The hyperornithinemia-hyperammonemia-homocitrullinuria (HHH) syndrome is a rare autosomal recessive inborn error of the urea cycle caused by mutations in the gene. Besides the well-known metabolic complications, patients often present intercurrent infections associated with acute hyperammonemia and metabolic decompensation. However, it is currently unknown whether intercurrent infections are associated with immunological alterations besides the known metabolic imbalances. Herein, we describe the case of a 3-years-old girl affected by the HHH syndrome caused by two novel gene mutations associated with immune phenotypic and functional alterations. She was admitted to the hospital with an episode of recurrent otitis, somnolence, confusion, and lethargy. Laboratory tests revealed severe hyperammonemia, elevated serum levels of liver transaminases, hemostasis alterations, hyperglutaminemia and strikingly increased orotic aciduria. Noteworthy, serum protein electrophoresis showed a reduction in the gamma globulin fraction. Direct sequencing of the gene revealed two heterozygous non-conservative substitutions in the exon 5: c.649G>A (p.Gly217Arg) and c.706A>G (p.Arg236Gly). analysis indicated that both mutations significantly impair protein structure and function and are consistent with the patient clinical status confirming the diagnosis of HHH syndrome. In addition, the immune analysis revealed reduced levels of serum IgG and striking phenotypic and functional alterations in the T and B cell immune compartments. Our study has identified two non-previously described mutations in the gene underlying the HHH syndrome. Moreover, we are reporting for the first time functional and phenotypic immunologic alterations in this rare inborn error of metabolism that would render the patient immunocompromised and might be related to the high frequency of intercurrent infections observed in patients bearing urea cycle disorders. Our results point out the importance of a comprehensive analysis to gain further insights into the underlying pathophysiology of the disease that would allow better patient care and quality of life.
Topics: Amino Acid Transport Systems, Basic; Child, Preschool; Female; Humans; Hyperammonemia; Mitochondrial Membrane Transport Proteins; Ornithine; Quality of Life; Urea Cycle Disorders, Inborn
PubMed: 35711415
DOI: 10.3389/fimmu.2022.861516 -
Frontiers in Neurology 2022Hereditary orotic aciduria (HOA) is a rare genetic disorder of pyrimidine metabolism caused by variations in the uridine monophosphate synthetase () gene and inheritance...
BACKGROUND
Hereditary orotic aciduria (HOA) is a rare genetic disorder of pyrimidine metabolism caused by variations in the uridine monophosphate synthetase () gene and inheritance are autosomal recessive. Heterozygous mutations can also lead to orotic aciduria without clinical consequence.
METHODS
We conducted molecular genetic analyses on proband using whole-exome sequencing (WES) and on 12 family members using Sanger sequencing for mutation. We analyzed the urine metabolites of family members carrying heterozygous variants with standard gas chromatography-mass spectrometry (GC-MS).
RESULTS
We identified a novel mutation (c.517G>C) in a Chinese-origin of orotic aciduria pedigree. The proband presented with epilepsy and intellectual disability (ID). Other mutation carriers in our pedigree presented with mild orotic aciduria without relevant medical complaints except for the proband.
CONCLUSION
Our study further expanded the genotype of orotic aciduria and highlighted the probability of misdiagnosis in clinical practice.
PubMed: 35356460
DOI: 10.3389/fneur.2022.819116 -
Journal of Cellular and Molecular... Apr 2021Urea cycle disorders (UCDs) are a group of rare metabolic conditions characterized by hyperammonemia and a broad spectrum of phenotypic severity. They are caused by the...
Urea cycle disorders (UCDs) are a group of rare metabolic conditions characterized by hyperammonemia and a broad spectrum of phenotypic severity. They are caused by the congenital deficiency in the eight biomolecules involved in urea cycle. In the present study, five cases of UCD were recruited and submitted to a series of clinical, biochemical, and genetic analysis with a combination of high throughput techniques. Moreover, in silico analysis was conducted on the identified missense genetic variants. Various clinical and biochemical indications (including profiles of amino acids and urinary orotic acids) of UCD were manifested by the five probands. Sequence analysis revealed nine diagnostic variants, including three novel ones, which caused Argininosuccinic aciduria (ASA) in one case, Carbamoyl phosphate synthetase 1deficiency (CPS1D) in two cases, Ornithine transcarbamylase deficiency (OTCD) in one case, and Citrin deficiency in 1case. Results of in silico biophysical analysis strongly suggested the pathogenicity of each the five missense variants and provided insight into their intramolecular impacts. In conclusion, this study expanded the genetic variation spectrum of UCD, gave solid evidence for counselling to the affected families, and should facilitate the functional study on the proteins in urea cycle.
Topics: Computer Simulation; DNA Mutational Analysis; Female; Humans; Infant; Infant, Newborn; Male; Mutation, Missense; Ornithine Carbamoyltransferase; Pedigree; Prognosis; Urea Cycle Disorders, Inborn
PubMed: 33611823
DOI: 10.1111/jcmm.16379 -
Molecular Genetics and Metabolism... Mar 2021Hereditary orotic aciduria (HOA) is a very rare inborn error of pyrimidine metabolism. It results from a defect of the uridine-5-monophosphate synthase () gene. To date,...
Hereditary orotic aciduria (HOA) is a very rare inborn error of pyrimidine metabolism. It results from a defect of the uridine-5-monophosphate synthase () gene. To date, only about twenty patients have been described. We report a case of HOA with a novel variant in the gene. A 17-year-old Emirati girl was born to first-cousin parents. During the first year, she had recurrent, severe infections including disseminated varicella. After evaluation for immunodeficiency, an impression of immunodeficiency of unknown etiology was presumed. Frequent episodes of pancytopenia were also noted. Bone marrow biopsy showed trilineage megaloblastoid maturation with dysplastic changes that were refractory to hematinic therapy. Also, she was noted to have failure to thrive, developmental delay and epilepsy. She was referred to the Genetics clinic where whole-exome sequencing (WES) was done and showed a novel homozygous variant in the gene confirming a diagnosis of HOA. She was started on uridine triacetate after which she showed clinical, hematologic and biochemical improvement. Although extremely rare, hereditary orotic aciduria should be suspected in any child with megaloblastic bone marrow, immunodeficiency or when developmental delay and anemia coexist.
PubMed: 33489760
DOI: 10.1016/j.ymgmr.2020.100703