Aciduria Research Articles

A Case Report of Isovaleric Acidemia without Acidosis

The deficiency of isovaleryl-CoA dehydrogenase leads to an inborn recessive error of leucine metabolism named isovaleric acidemia (IVA). Its presentation may be either in the neonatal period as an acute episode of metabolic acidosis or later as a “chronic intermittent form.” Normal development is promoted by early diagnosis and treatment with a protein-restricted diet and supplementation with carnitine and glycine. The present case was a 35-day-old boy admitted with seizures, whose initial screening test was in favor of organic acidemia of the isovaleric acidemia type (Ammonia: 200 μmol/L). As the venous blood gas (VBG) analysis revealed no acidosis, newborn metabolic screening was repeated. Typical laboratory findings and elevated levels of C5 and C5/C2 confirmed isovaleric acidemia again. As the above patient had no acidosis while the other tests, including laboratory and genetic analysis, were in favor of IVA, he was considered to be a rare case.

Gluteric aciduria ( type-I) Presenting as Bilateral Subdural Hygroma- A Case Report with Literature Review

Glutaric aciduria type 1 (GA-1) is an autosomal recessive rare neurometabolic disorder caused by absent or deficient activity of glutaryl- CoA dehydrogenase. Patient with gluteric aciduria are more likely to develop collection in the subdural space secondary to cerebral atrophy and expansion of CSF spaces. A 1 year and 10 months toddler presented with increased head circumference since birth and generalized seizure for last few days. Neuroimaging showed bilateral subdural collection of CSF intensity. Bilateral subdural peritoneal shunt was inserted. With early diagnosis and adequate treatment , the majority of children with gluteric aciduria type-I are able to live normal. However treatment for gluteric aciduria type-I must be continued for life to avoid lifethreatening complications Bang. J Neurosurgery 2024; 13(2): 162-164

Associations between elevated uric acid and brain imaging abnormalities in pediatric patients with methylmalonic acidemia under 5 years of age

Methylmalonic acidemia (MMA) is the most common inborn organic acidemia, presenting multisystemic complications. Uric acid may have neurotoxic or neuroprotective effects due to its antioxidant or pro-inflammatory properties; however, its role in MMA brain injury remains unclear. We examined the correlation between the serum uric acid levels and brain imaging features of MMA. Data were collected from a cross-sectional study of 216 patients with MMA and 216 healthy matched controls aged 0–5 years in China. Serum uric acid levels were measured, and magnetic resonance imaging and computed tomography findings were retrieved from hospital records. Overall, 74.1% patients had brain abnormalities. Patients in the MMA group with abnormal brain imaging had higher serum uric acid levels than those in the MMA normal brain imaging and control groups. The area under the curve of serum uric acid was 0.74, 0.91, and 0.93 for MMA diagnosis with abnormal brain images, basal ganglia changes, and globus pallidus changes, respectively. Higher serum uric acid levels were independently associated with abnormal brain images. Children aged < 5 years with abnormal brain images in MMA exhibit elevated serum uric acid levels, serving as an effective auxiliary diagnostic indicator and independent risk factor for brain tissue injury.

Intrathecal baclofen therapy as treatment for spasticity and dystonia: Review of cases in a pediatric palliative care unit

IntroductionPatients managed in the Pediatric Palliative Care Integral Unit (PPCIU) have serious neurological conditions that involve significant damage at central nervous system level. The movement disorder is a very common clinical problem and for the patients where an adequate control of muscle tone is not achieved with usual techniques or drugs, intrathecal baclofen therapy (IBT) should be considered. Materials and methodsDescriptive retrospective study based on the review of clinical records of patients who received IBT being followed by the PPCIU of Madrid Autonomous Region in the timeframe between September 2012 and February 2021. ResultsIBT was implanted in 8 patients affected by infantile cerebral palsy (ICP) with a Gross Motor Function Scale (GMFCS) IV–V, 3 patients was a Pantothenate kinase deficit-associated neurodegeneration (PKAN), 2 had Acquired Brain Damage, and the remaining 3 had, respectively, 2 glutaric aciduria type I (GA-1), and poly-malformative syndrome. In all patients we observed a period of clinical stability after IBT, we call this period “honeymoon”. Two patients died while in the honeymoon period, at 24.9 and 19.6 months from implantation of the pump; the median of duration of the honeymoon period in the remaining 14 was 14.4 months (IQ: 8.3–25.8). ConclusionsIBT was not only used in patients with non-progressive diseases, but also in the group of patients with neurodegenerative or progressive diseases. In all of them, after implantation of the device, we have objectified a period of clinical stability and a better control of muscle tone disorders.

Enhanced differentiation between 3‐hydroxyglutaric and 2‐hydroxyglutaric acids facilitates diagnostic testing for glutaric aciduria type 1

AbstractGlutaric aciduria type 1 (GA1) is an inherited neurometabolic disorder, in which deficiency of glutaryl‐CoA dehydrogenase leads to accumulation of glutaric acid (GA) and 3‐hydroxyglutaric acid (3‐HG). Some low excretors may exhibit only slight elevation of urinary 3‐HG, with normal urinary GA, yet are at significant risk of severe clinical disease. Accurate quantitation of urinary 3‐HG is crucial in diagnostic workup for GA1, but in this context, current gas chromatography–mass spectrometry (GC–MS) methods have inherent analytical challenges. Co‐elution and spectral similarities of the 3‐HG and 2‐HG structural isomers can cause difficulties in quantitation of slightly elevated 3‐HG. Our laboratory recently acquired a gas chromatography system coupled to a triple quadrupole mass spectrometer (GC–MS/MS), and we took advantage of its increased sensitivity and specificity to improve our existing GC–MS method. A stable isotope dilution process is used, with sample treatment consisting of a double liquid–liquid extraction followed by a trimethylsilyl derivatization. The transitions m/z 349 → 333 for 3‐HG and m/z 349 → 321 for 2‐HG were selected to differentiate these two isobaric molecules based on their characteristic fragments, thus minimizing interferences despite co‐elution. Method validation demonstrated satisfactory precision and accuracy. Using GC–MS/MS instead of GC–MS allowed us to decrease the required specimen volume, number of sample processing steps, chromatographic run time, and instrument maintenance. This enhanced assay facilitates clinical laboratory testing for GA1, both in confirmatory protocols following positive newborn screening and in diagnostic investigation of patients with suggestive signs or symptoms.

Prediction of inherited metabolic disorders using tandem mass spectrometry data with the help of artificial neural networks.

Tandem mass spectrometry is helpful in diagnosing amino acid metabolism disorders, organic acidemias, and fatty acid oxidation disorders and can provide rapid and accurate diagnosis for inborn errors of metabolism. The aim of this study was to predict inborn errors of metabolism in children with the help of artificial neural networks using tandem mass spectrometry data. Forty-seven and 13 parameters of tandem mass spectrometry datasets obtained from 2938 different patients were respectively taken into account to train and test the artificial neural networks. Different artificial neural network models were established to obtain better prediction performances. The obtained results were compared with each other for fair comparisons. The best results were obtained by using the rectified linear unit activation function. One, two, and three hidden layers were considered for artificial neural network models established with both 47 and 13 parameters. The sensitivity of model B2 for definitive inherited metabolic disorders was found to be 80%. The accuracy rates of model A3 and model B2 are 99.3% and 99.2%, respectively. The area under the curve value of model A3 was 0.87, while that of model B2 was 0.90. The results showed that the proposed artificial neural networks are capable of predicting inborn errors of metabolism very accurately. Therefore, developing new technologies to identify and predict inborn errors of metabolism will be very useful.

Long-term neurodevelopmental outcomes following liver transplantation for metabolic disease-a single centre experience.

This study describes the neurodevelopmental outcome of children with urea cycle disorders (UCD) and organic acidemias (OA) preliver transplant (LT), 1-year, and 3-years post-LT. We performed a retrospective chart review of children with OA or UCD transplanted between January 2014 and December 2021. Standardized motor and cognitive assessment scores were collected from children who had ≥1 motor/cognitive assessment at any timepoint. Pre-LT brain magnetic resonance imaging (MRI) was graded. Associations between demographic/medical variables and neurodevelopmental outcomes were explored. Twenty-six children (64% male) underwent LT at a median age of 1.4 (interquartile range 0.71, 3.84) years. Fifteen (58%) had a UCD diagnosis, 14 (54%) required dialysis for hyperammonemia, and 10 (42%) had seizures typically around diagnosis. The proportion of children with gross motor scores >1 standard deviation (SD) below the mean increased across timepoints, and ≥50% demonstrated general intellect scores >2 SD below the mean at each timepoint. The following significant associations were noted: UCD diagnoses with lower general intellect scores (p = 0.019); arginosuccinate lyase deficiency diagnosis with lower visual motor scores at 3-years post-LT (p = 0.035); a history of seizures pre-LT with lower general intellect (>2SD below the mean) at 3-years post-LT (p = 0.020); dialysis pre-LT with lower motor scores (>1 SD below the mean) at 1-year post-LT (p = 0.039); pre-emptive LT with higher general intellect scores at 3-years post-LT (p = 0.001). MRI gradings were not associated with developmental scores. In our single centre study, children with UCD or OA had a higher prevalence of developmental impairment post-LT compared to population norms. Earlier screening, pre-emptive transplant, and rehabilitation may optimize long-term outcomes.

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.

MRI in LARS1 deficiency-Spectrum, patterns, and correlation with acute neurological deterioration.

Leucine aminoacyl tRNA-synthetase 1 (LARS1)-deficiency (infantile liver failure syndrome type 1 (ILFS1)) has a multisystemic phenotype including fever-associated acute liver failure (ALF), chronic neurologic abnormalities, and encephalopathic episodes. In order to better characterize encephalopathic episodes and MRI changes, 35 cranial MRIs from 13 individuals with LARS1 deficiency were systematically assessed and neurological phenotype was analyzed. All individuals had developmental delay and 10/13 had seizures. Encephalopathic episodes in 8/13 were typically associated with infections, presented with seizures and reduced consciousness, mostly accompanied by hepatic dysfunction, and recovery in 17/19 episodes. Encephalopathy without hepatic dysfunction occurred in one individual after liver transplantation. On MRI, 5/7 individuals with MRI during acute encephalopathy had deep gray matter and brainstem changes. Supratentorial cortex involvement (6/13) and cerebellar watershed injury (4/13) occurred with seizures and/or encephalopathy. Abnormal brainstem contour on sagittal images (8/13), atrophy (8/13), and myelination delay (8/13) were not clearly associated with encephalopathy. The pattern of deep gray matter and brainstem changes are apparently characteristic of encephalopathy in LARS1-deficiency, differing from patterns of hepatic encephalopathy or metabolic stroke in organic acidurias and mitochondrial diseases. While the pathomechanism remains unclear, fever and energy deficit during infections might be causative; thus, sufficient glucose and protein intake along with pro-active fever management is suggested. As severe episodes were observed during influenza infections, we strongly recommend seasonal vaccination.

A compound heterozygote case of glutaric aciduria type II in a patient carrying a novel candidate variant in ETFDH gene: A case report and literature review on compound heterozygote cases.

Glutaric aciduria type II (GA2) is a rare genetic disorder inherited in an autosomal recessive manner. Double dosage mutations in GA2 corresponding genes, ETFDH, ETFA, and ETFB, lead to defects in the catabolism of fatty acids, and amino acids lead to broad-spectrum phenotypes, including muscle weakness, developmental delay, and seizures. product of these three genes have crucial role in transferring electrons to the electron transport chain (ETC), but are not directly involve in ETC complexes. Here, by using exome sequencing, the cause of periodic cryptic gastrointestinal complications in a 19-year-old girl was resolved after years of diagnostic odyssey. Protein modeling for the novel variant served as another line of validation for it. Exome Sequencing (ES) identified two variants in ETFDH: ETFDH:c.926T>G and ETFDH:c.1141G>C. These variants are likely contributing to the crisis in this case. To the best of our knowledge at the time of writing this manuscript, variant ETFDH:c.926T>G is reported here for the first time. Clinical manifestations of the case and pathological analysis are in consistent with molecular findings. Protein modeling provided another line of evidence proving the pathogenicity of the novel variant. ETFDH:c.926T>G is reported here for the first time in relation to the causation GA2. Given the milder symptoms in this case, a review of GA2 cases caused by compound heterozygous mutations was conducted, highlighting the range of symptoms observed in these patients, from mild fatigue to more severe outcomes. The results underscore the importance of comprehensive genetic analysis in elucidating the spectrum of clinical presentations in GA2 and guiding personalized treatment strategies.

Role of Botulinum Toxin in Treatment of Secondary Dystonia: A Case Series and Overview of Literature.

Dystonia can present in primary and secondary forms, depending on co-occurring symptoms and syndromic associations. In contrast to primary dystonia, secondary forms of dystonia are often associated with lesions in the putamen or globus pallidus. Such disorders are commonly neurodegenerative or neurometabolic conditions which produce varied neurologic as well as systemic manifestations other than dystonia. Chemo-denervation with botulinum toxin has been successfully used for focal or segmental dystonia. However, studies evaluating the effect of BoNT therapy on patients with secondary dystonia are sparse, given the heterogeneity in etiology and presentation. We present a series of patients with secondary dystonia who were managed with botulinum toxin therapy. Patients included in this series had a confirmed neurometabolic cause of dystonia. A total of 14 patients, with ages ranging from 17 to 36 years, with disorders including Wilson's disease, pantothenate kinase-associated neurodegeneration (PKAN), Niemann-Pick disease type C (NPC), glutaric aciduria type 1, Sanfilippo syndrome (Mucopolysaccharidosis Type IIIb), and GM2 gangliosidosis (Sandhoff disease) are presented. Most patients experienced a mild to moderate improvement in treated dystonia with benefits ranging from 6 to 12 weeks, with the median length of the benefits lasting approximately eight weeks, without any significant adverse effects. Although the secondary causes of dystonia are complex and diverse, our presented data and the available reports of the use of botulinum toxin support the conclusion that chemo-denervation plays an important role in symptom alleviation.

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.

Molecular genetic analysis of candidate genes for glutaric aciduria type II in a cohort of patients from Queensland, Australia

Glutaric aciduria type II (GAII) is a heterogeneous genetic disorder affecting mitochondrial fatty acid, amino acid and choline oxidation. Clinical manifestations vary across the lifespan and onset may occur at any time from the early neonatal period to advanced adulthood. Historically, some patients, in particular those with late onset disease, have experienced significant benefit from riboflavin supplementation. GAII has been considered an autosomal recessive condition caused by pathogenic variants in the gene encoding electron-transfer flavoprotein ubiquinone-oxidoreductase (ETFDH) or in the genes encoding electron-transfer flavoprotein subunits A and B (ETFA and ETFB respectively). Variants in genes involved in riboflavin metabolism have also been reported. However, in some patients, molecular analysis has failed to reveal diagnostic molecular results. In this study, we report the outcome of molecular analysis in 28 Australian patients across the lifespan, 10 paediatric and 18 adult, who had a diagnosis of glutaric aciduria type II based on both clinical and biochemical parameters. Whole genome sequencing was performed on 26 of the patients and two neonatal onset patients had targeted sequencing of candidate genes. The two patients who had targeted sequencing had biallelic pathogenic variants (in ETFA and ETFDH). None of the 26 patients whose whole genome was sequenced had biallelic variants in any of the primary candidate genes. Interestingly, nine of these patients (34.6%) had a monoallelic pathogenic or likely pathogenic variant in a single primary candidate gene and one patient (3.9%) had a monoallelic pathogenic or likely pathogenic variant in two separate genes within the same pathway. The frequencies of the damaging variants within ETFDH and FAD transporter gene SLC25A32 were significantly higher than expected when compared to the corresponding allele frequencies in the general population. The remaining 16 patients (61.5%) had no pathogenic or likely pathogenic variants in the candidate genes. Ten (56%) of the 18 adult patients were taking the selective serotonin reuptake inhibitor antidepressant sertraline, which has been shown to produce a GAII phenotype, and another two adults (11%) were taking a serotonin-norepinephrine reuptake inhibitor antidepressant, venlafaxine or duloxetine, which have a mechanism of action overlapping that of sertraline. Riboflavin deficiency can also mimic both the clinical and biochemical phenotype of GAII. Several patients on these antidepressants showed an initial response to riboflavin but then that response waned. These results suggest that the GAII phenotype can result from a complex interaction between monoallelic variants and the cellular environment. Whole genome or targeted gene panel analysis may not provide a clear molecular diagnosis.

Evaluation of the Frequency of Blood Ammonia Test Requests in Pediatric Clinics Before and After the Establishment of the Pediatric Metabolism Department

Abstract Background/Aims: Hyperammonemia causes severe mortality and morbidity when left unnoticed. We aimed to compare the number of ammonia test requests before and after establishing the Pediatric Metabolism Department (PMD) in a pediatric clinic. Methods: The study was conducted retrospectively between 15/11/2022-16/11/2023. Study data were evaluated before (pre-group) and after (post-group) the establishment of PMD. Results: Two hundred eighty-five admissions were assessed in the study. There were 99 admissions in the pre-group and 186 in the post-group. There were 17 admissions for different reasons in the pre-group and 29 in the post-group. The most common reasons for admission were elevated transaminases, seizures, vomiting, and metabolic acidosis. Definitive diagnosis was made in 16 (17.6%) patients admitted in the pre-group and 39 (23.8%) in the post-group. The most common diagnoses were genetic syndromes, mitochondrial diseases, and organic acidemias. Twenty-one patients were diagnosed with inherited metabolic diseases (IMDs). Mitochondrial diseases were the most commonly diagnosed IMD (8(38%)). An ammonia test was requested from 8 of 15 pediatric subunits in the pre-group and 13 in the post-group. In the pre-group, the pediatric subunit where ammonia was requested the most was the Pediatric Neurology Polyclinic (n=25 (25.3%)). In the post-group, the subunit that required the highest number of ammonia tests was the PMD (68(23.9%)). In the ROC analysis conducted for the predictive power of the initial ammonia level in requesting a control ammonia test, the area under the curve is 0.927, and the p-value is 0.001. For the cut-off value of 60.3 µmol/l, the sensitivity was 90.9%, and the specificity was 88.6%. Conclusions: After the establishment of PMD, an increase in ammonia test requests, in the diversity of reasons for requesting ammonia testing from admissions, and in IMD diagnosis were detected, and the positive effect of PMD on pediatricians' awareness of hyperammonemia was found.

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

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. 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. 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. 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. 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. 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.

Inherited metabolic disorders in Cyprus

Selective screening for inherited metabolic disorders (IMD) began in Cyprus in 1990. Over the last thirty-three years 7388 patients were investigated for IMD and 200 diagnoses were made (diagnostic yield 2.7%). The existence of a single laboratory of Biochemical Genetics for the whole island facilitated the creation of a national registry for IMD. The minimal prevalence of IMD in Cyprus is 53.3 cases per 100,000 live births. The most common group are disorders of amino acid metabolism (41.0%), followed by disorders of carbohydrate metabolism (16.5%), disorders of complex molecule degradation (16.5%), mitochondrial disorders (10.5%) and disorders of vitamin and co-factor metabolism (5.5%). Hyperphenylalaninaemia is the most common IMD (14.0%) followed by galactosaemia (7.0%), glutaric aciduria type I (5.5%) and MSUD (4.0%). Some disorders were found to have a relatively high incidence in specific communities, for example Sandhoff disease among the Cypriot Maronites and GM1 gangliosidosis in one particular area of the island. Other disorders were found to have a relatively higher overall incidence, compared to other Caucasian populations, for example galactosaemia, glutaric aciduria type I and MSUD, while fatty acid oxidation defects, Gaucher disease and classic PKU were found to have a relatively lower incidence. Molecular characterization of selected disorders revealed many novel genetic variants, specific to the Cypriot population.

162 Patient with Adenosine Deaminase Severe Combined Immunodeficiency (ADA-SCID) and Glutaric Aciduria Type 1 (GA1) Successfully treated with delayed Hematopoietic Stem Cell Transplant (HSCT)

162 Patient with Adenosine Deaminase Severe Combined Immunodeficiency (ADA-SCID) and Glutaric Aciduria Type 1 (GA1) Successfully treated with delayed Hematopoietic Stem Cell Transplant (HSCT)

Newborn screening in France: news and perspectives

Newborn screening is a major public health concern. In France, it was established in 1972 with systematic screening for phenylketonuria. Subsequently, other screenings, including congenital hypothyroidism, congenital adrenal hyperplasia, cystic fibrosis, and sickle cell disease, were added. The introduction of tandem mass spectrometry in screening laboratories in 2020 enabled the inclusion of eight additional inherited metabolic diseases: aminoacidopathies (tyrosinemia type I, maple syrup urine disease, and homocystinuria), organic acidurias (isovaleric and glutaric type I acidurias), and disorders of fatty acid metabolism (MCADD, long-chain 3-hydroxyacyl-CoA dehydrogenase deficiency (LCHADD), and primary carnitine deficiency). We briefly present these newly added diseases, of which public awareness is still incomplete.

Comparative analysis of inherited metabolic diseases in normal newborns and high-risk children: Insights from a 10-year study in Shanghai

BackgroundCompare the differences between normal newborns and high-risk children with inherited metabolic diseases. The disease profile includes amino acidemias, fatty acid oxidation disorders, and organic acidemias. MethodsData was collected on newborns and children from high-risk populations in Shanghai from December 2010 to December 2020. Results232,561 newborns were screened for disorders of organic, amino acid, and fatty acid metabolism. The initial positive rate was 0.66 % (1,526/232,561) and the positive recall rate was 77.85 %. The positive predictive value is 4.71 %. Among them, 56 cases were diagnosed as metabolic abnormalities. The total incidence rate is 1:4153. Hyperphenylalaninemia and short-chain acyl-CoA dehydrogenase are the most common diseases in newborns. In addition, in 56 children, 39 (69.42 %) were diagnosed by genetic sequencing. Some hotspot mutations in 14 IEMs have been observed, including PAH gene c.728G > A, c.611A > G, and ACADS gene c. 1031A > G, c.164C > T. A total of 49,860 symptomatic patients were screened, of which 185 were diagnosed with IEM, with a detection rate of 0.37 %. The most commonly diagnosed diseases in high-risk infants aremethylmalonic acidemia and hyperphenylalaninemia. ConclusionThere are more clinical cases of congenital metabolic errors diagnosed by tandem mass spectrometry than newborn screening. The spectrum of diseases, prevalence, and genetic characteristics of normal newborns and high-risk children are quite different.