Inborn Errors of RNA Lariat Metabolism in Humans with Brainstem Viral Infection.

Viruses that are typically benign sometimes invade the brainstem in otherwise healthy children. We report bi-allelic DBR1 mutations in unrelated patients from different ethnicities, each of whom had brainstem infection due to herpes simplex virus 1 (HSV1), influenza virus, or norovirus. DBR1 encodes the only known RNA lariat debranching enzyme. We show that DBR1 expression is ubiquitous, but strongest in the spinal cord and brainstem. We also show that all DBR1 mutant alleles are severely hypomorphic, in terms of expression and function. The fibroblasts of DBR1-mutated patients contain higher RNA lariat levels than control cells, this difference becoming even more marked during HSV1 infection. Finally, we show that the patients' fibroblasts are highly susceptible to HSV1. RNA lariat accumulation and viral susceptibility are rescued by wild-type DBR1. Autosomal recessive, partial DBR1 deficiency underlies viral infection of the brainstem in humans through the disruption of tissue-specific and cell-intrinsic immunity to viruses.

Plasma lipidomics analysis reveals altered profile of triglycerides and phospholipids in children with Medium-Chain Acyl-CoA dehydrogenase deficiency.

Medium-chain acyl-CoA dehydrogenase deficiency (MCADD) is the most prevalent mitochondrial fatty acid ß-oxidation disorder. In this study, we assessed the variability of the lipid profile in MCADD by analysing plasma samples obtained from 25 children with metabolically controlled MCADD (following a normal diet with frequent feeding and under l-carnitine supplementation) and 21 paediatric control subjects (CT). Gas chromatography-mass spectrometry was employed for the analysis of esterified fatty acids, while high-resolution C18-liquid chromatography-mass spectrometry was used to analyse lipid species. We identified a total of 251 lipid species belonging to 15 distinct lipid classes. Principal component analysis revealed a clear distinction between the MCADD and CT groups. Univariate analysis demonstrated that 126 lipid species exhibited significant differences between the two groups. The lipid species that displayed the most pronounced variations included triacylglycerols and phosphatidylcholines containing saturated and monounsaturated fatty acids, specifically C14:0 and C16:0, which were found to be more abundant in MCADD. The observed changes in the plasma lipidome of children with non-decompensated MCADD suggest an underlying alteration in lipid metabolism. Therefore, longitudinal monitoring and further in-depth investigations are warranted to better understand whether such alterations are specific to MCADD children and their potential long-term impacts.

Modeling Lysosomal Storage Disorders in an Innovative Way: Establishment and Characterization of Stem Cell Lines from Human Exfoliated Deciduous Teeth of Mucopolysaccharidosis Type II Patients.

Among the many lysosomal storage disorders (LSDs) that would benefit from the establishment of novel cell models, either patient-derived or genetically engineered, is mucopolysaccharidosis type II (MPS II). Here, we present our results on the establishment and characterization of two MPS II patient-derived stem cell line(s) from deciduous baby teeth. To the best of our knowledge, this is the first time a stem cell population has been isolated from LSD patient samples obtained from the dental pulp. Taking into account our results on the molecular and biochemical characterization of those cells and the fact that they exhibit visible and measurable disease phenotypes, we consider these cells may qualify as a valuable disease model, which may be useful for both pathophysiological assessments and in vitro screenings. Ultimately, we believe that patient-derived dental pulp stem cells (DPSCs), particularly those isolated from human exfoliated deciduous teeth (SHEDs), may represent a feasible alternative to induced pluripotent stem cells (iPSCs) in many labs with standard cell culture conditions and limited (human and economic) resources.

Mitochondrial Fatty Acid ß-Oxidation Disorders: From Disease to Lipidomic Studies-A Critical Review.

Fatty acid oxidation disorders (FAODs) are inborn errors of metabolism (IEMs) caused by defects in the fatty acid (FA) mitochondrial ß-oxidation. The most common FAODs are characterized by the accumulation of medium-chain FAs and long-chain (3-hydroxy) FAs (and their carnitine derivatives), respectively. These deregulations are associated with lipotoxicity which affects several organs and potentially leads to life-threatening complications and comorbidities. Changes in the lipidome have been associated with several diseases, including some IEMs. In FAODs, the alteration of acylcarnitines (CARs) and FA profiles have been reported in patients and animal models, but changes in polar and neutral lipid profile are still scarcely studied. In this review, we present the main findings on FA and CAR profile changes associated with FAOD pathogenesis, their correlation with oxidative damage, and the consequent disturbance of mitochondrial homeostasis. Moreover, alterations in polar and neutral lipid classes and lipid species identified so far and their possible role in FAODs are discussed. We highlight the need of mass-spectrometry-based lipidomic studies to understand (epi)lipidome remodelling in FAODs, thus allowing to elucidate the pathophysiology and the identification of possible biomarkers for disease prognosis and an evaluation of therapeutic efficacy.

Plasma Phospholipidomic Profile Differs between Children with Phenylketonuria and Healthy Children.

Phenylketonuria (PKU) is a disease of the catabolism of phenylalanine (Phe), caused by an impaired function of the enzyme phenylalanine hydroxylase. Therapeutics is based on the restriction of Phe intake, which mostly requires a modification of the diet. Dietary restrictions can lead to imbalances in specific nutrients, including lipids. In the present study, the plasma phospholipidome of PKU and healthy children (CT) was analyzed by hydrophilic interaction liquid chromatography-tandem mass spectrometry and gas chromatography-mass spectrometry. Using this approach, 187 lipid species belonging to nine different phospholipid classes and three ceramides were identified. Principal component analysis of the lipid species data set showed a distinction between PKU and CT groups. Univariate analysis revealed that 146 species of phospholipids were significantly different between both groups. Lipid species showing significant variation included phosphatidylcholines, containing polyunsaturated fatty acids (PUFA), which were more abundant in PKU. The high level of PUFA-containing lipid species in children with PKU may be related to a diet supplemented with PUFA. This study was the first report comparing the plasma polar lipidome of PKU and healthy children, highlighting that the phospholipidome of PKU children is significantly altered compared to CT. However, further studies with larger cohorts are needed to clarify whether these changes are specific to phenylketonuric children.

Congenital Disorders of Glycosylation in Portugal-Two Decades of Experience.

OBJECTIVE: To describe the clinical, biochemical, and genetic features of both new and previously reported patients with congenital disorders of glycosylation (CDGs) diagnosed in Portugal over the last 20 years. STUDY DESIGN: The cohort includes patients with an unexplained multisystem or single organ involvement, with or without psychomotor disability. Serum sialotransferrin isoforms and, whenever necessary, apolipoprotein CIII isoforms and glycan structures were analyzed. Additional studies included measurement of phosphomannomutase (PMM) activity and analysis of lipid-linked oligosaccharides in fibroblasts. Sanger sequencing and massive parallel sequencing were used to identify causal variants or the affected gene, respectively. RESULTS: Sixty-three individuals were diagnosed covering 14 distinct CDGs; 43 patients diagnosed postnatally revealed a type 1, 14 a type 2, and 2 a normal pattern on serum transferrin isoelectrofocusing. The latter patients were identified by whole exome sequencing. Nine of them presented also a hypoglycosylation pattern on apolipoprotein CIII isoelectrofocusing, pointing to an associated O-glycosylation defect. Most of the patients (62%) are PMM2-CDG and the remaining carry pathogenic variants in ALG1, ATP6AP1, ATP6AP2, ATP6V0A2, CCDC115, COG1, COG4, DPAGT1, MAN1B1, SLC35A2, SRD5A3, RFT1, or PGM1. CONCLUSIONS: Portuguese patients with CDGs are presented in this report, some of them showing unique clinical phenotypes. Among the 14 genes mutated in Portuguese individuals, 8 are shared with a previously reported Spanish cohort. However, regarding the mutational spectrum of PMM2-CDG, the most frequent CDG, a striking similarity between the 2 populations was found, as only 1 mutated allele found in the Portuguese group has not been reported in Spain.

Lipids and phenylketonuria: Current evidences pointed the need for lipidomics studies.

Phenylketonuria (PKU) is the most prevalent inborn error of amino acid metabolism. The disease is due to the deficiency of phenylalanine (Phe) hydroxylase activity, which causes the accumulation of Phe. Early diagnosis through neonatal screening is essential for early treatment implementation, avoiding cognitive impairment and other irreversible sequelae. Treatment is based on Phe restriction in the diet that should be maintained throughout life. High dietary restrictions can lead to imbalances in specific nutrients, notably lipids. Previous studies in PKU patients revealed changes in levels of plasma/serum lipoprotein lipids, as well as in fatty acid profile of plasma and red blood cells. Most studies showed a decrease in important polyunsaturated fatty acids, namely DHA (22:6n-3), AA (20:4n-6) and EPA (20:5n-6). Increased oxidative stress and subsequent lipid peroxidation have also been observed in PKU. Despite the evidences that the lipid profile is changed in PKU patients, more studies are needed to understand in detail how lipidome is affected. As highlighted in this review, mass spectrometry-based lipidomics is a promising approach to evaluate the effect of the diet restrictions on lipid metabolism in PKU patients, monitor their outcome, namely concerning the risk for other chronic diseases, and find possible prognosis biomarkers.

Experience on statin therapy in paediatric age: retrospective study in a Portuguese referral centre.

BACKGROUND: The use of statins in children, although not frequent, is recommended in specific clinical contexts, namely, familial hypercholesterolaemia, conditions carrying a moderate-high cardiovascular risk and sub-optimal cholesterol levels after implementation of lifestyle modifications. The aim of this study is to characterise children with dyslipidaemia managed with statins, followed at a tertiary referral centre in central Portugal. METHODS AND RESULTS: The authors carried out a retrospective and descriptive study made up of 66 patients (50% males, mean age of therapy onset 11.9 years) followed up at the Cardiovascular Clinic of a tertiary referral centre between January, 2012, and May, 2018. Clinical, analytical, and echocardiographic parameters were analysed. About 60.6% had clinical and/or molecular diagnosis of familial hypercholesterolaemia. On average, each patient had three cardiovascular risk factors, obesity (31%) being most prevalent, followed by arterial hypertension (14%). Statin therapy showed a statistically significant reduction in the lipid profile, particularly in the total cholesterol (23%) and low-density lipoprotein cholesterol (30%) levels, as well as in the carotid intima-media thickness (p = 0.015). Hepatic and muscle integrity markers were within normal range. CONCLUSIONS: Statins are safe and efficient in the management of children with hypercholesterolaemia. Our study showed that apart from its lipid-lowering properties, it also reduced significantly the carotid intima-media thickness and, implicitly, the cardiovascular risk of these patients.

CCDC115 Deficiency Causes a Disorder of Golgi Homeostasis with Abnormal Protein Glycosylation.

Disorders of Golgi homeostasis form an emerging group of genetic defects. The highly heterogeneous clinical spectrum is not explained by our current understanding of the underlying cell-biological processes in the Golgi. Therefore, uncovering genetic defects and annotating gene function are challenging. Exome sequencing in a family with three siblings affected by abnormal Golgi glycosylation revealed a homozygous missense mutation, c.92T>C (p.Leu31Ser), in coiled-coil domain containing 115 (CCDC115), the function of which is unknown. The same mutation was identified in three unrelated families, and in one family it was compound heterozygous in combination with a heterozygous deletion of CCDC115. An additional homozygous missense mutation, c.31G>T (p.Asp11Tyr), was found in a family with two affected siblings. All individuals displayed a storage-disease-like phenotype involving hepatosplenomegaly, which regressed with age, highly elevated bone-derived alkaline phosphatase, elevated aminotransferases, and elevated cholesterol, in combination with abnormal copper metabolism and neurological symptoms. Two individuals died of liver failure, and one individual was successfully treated by liver transplantation. Abnormal N- and mucin type O-glycosylation was found on serum proteins, and reduced metabolic labeling of sialic acids was found in fibroblasts, which was restored after complementation with wild-type CCDC115. PSI-BLAST homology detection revealed reciprocal homology with Vma22p, the yeast V-ATPase assembly factor located in the endoplasmic reticulum (ER). Human CCDC115 mainly localized to the ERGIC and to COPI vesicles, but not to the ER. These data, in combination with the phenotypic spectrum, which is distinct from that associated with defects in V-ATPase core subunits, suggest a more general role for CCDC115 in Golgi trafficking. Our study reveals CCDC115 deficiency as a disorder of Golgi homeostasis that can be readily identified via screening for abnormal glycosylation in plasma.

Clinical, neuroradiological, and biochemical features of SLC35A2-CDG patients.

SLC35A2-CDG is caused by mutations in the X-linked SLC35A2 gene encoding the UDP-galactose transporter. SLC35A2 mutations lead to hypogalactosylation of N-glycans. SLC35A2-CDG is characterized by severe neurological symptoms and, in many patients, early-onset epileptic encephalopathy. In view of the diagnostic challenges, we studied the clinical, neuroradiological, and biochemical features of 15 patients (11 females and 4 males) with SLC35A2-CDG from various centers. We describe nine novel pathogenic variations in SLC35A2. All affected individuals presented with a global developmental delay, and hypotonia, while 70% were nonambulatory. Epilepsy was present in 80% of the patients, and in EEG hypsarrhythmia and findings consistent with epileptic encephalopathy were frequently seen. The most common brain MRI abnormality was cerebral atrophy with delayed myelination and multifocal inhomogeneous abnormal patchy white matter hyperintensities, which seemed to be nonprogressive. Thin corpus callosum was also common, and all the patients had a corpus callosum shorter than normal for their age. Variable dysmorphic features and growth deficiency were noted. Biochemically, normal mucin type O-glycosylation and lipid glycosylation were found, while transferrin mass spectrometry was found to be more specific in the identification of SLC35A2-CDG, as compared to routine screening tests. Although normal glycosylation studies together with clinical variability and genetic results complicate the diagnosis of SLC35A2-CDG, our data indicate that the combination of these three elements can support the pathogenicity of mutations in SLC35A2.

Phenotype, treatment practice and outcome in the cobalamin-dependent remethylation disorders and MTHFR deficiency: Data from the E-HOD registry.

AIM: To explore the clinical presentation, course, treatment and impact of early treatment in patients with remethylation disorders from the European Network and Registry for Homocystinurias and Methylation Defects (E-HOD) international web-based registry. RESULTS: This review comprises 238 patients (cobalamin C defect n = 161; methylenetetrahydrofolate reductase deficiency n = 50; cobalamin G defect n = 11; cobalamin E defect n = 10; cobalamin D defect n = 5; and cobalamin J defect n = 1) from 47 centres for whom the E-HOD registry includes, as a minimum, data on medical history and enrolment visit. The duration of observation was 127 patient years. In 181 clinically diagnosed patients, the median age at presentation was 30 days (range 1 day to 42 years) and the median age at diagnosis was 3.7 months (range 3 days to 56 years). Seventy-five percent of pre-clinically diagnosed patients with cobalamin C disease became symptomatic within the first 15 days of life. Total homocysteine (tHcy), amino acids and urinary methylmalonic acid (MMA) were the most frequently assessed disease markers; confirmatory diagnostics were mainly molecular genetic studies. Remethylation disorders are multisystem diseases dominated by neurological and eye disease and failure to thrive. In this cohort, mortality, thromboembolic, psychiatric and renal disease were rarer than reported elsewhere. Early treatment correlates with lower overall morbidity but is less effective in preventing eye disease and cognitive impairment. The wide variation in treatment hampers the evaluation of particular therapeutic modalities. CONCLUSION: Treatment improves the clinical course of remethylation disorders and reduces morbidity, especially if started early, but neurocognitive and eye symptoms are less responsive. Current treatment is highly variable. This study has the inevitable limitations of a retrospective, registry-based design.

ALG1-CDG: Clinical and Molecular Characterization of 39 Unreported Patients.

Congenital disorders of glycosylation (CDG) arise from pathogenic mutations in over 100 genes leading to impaired protein or lipid glycosylation. ALG1 encodes a ß1,4 mannosyltransferase that catalyzes the addition of the first of nine mannose moieties to form a dolichol-lipid linked oligosaccharide intermediate required for proper N-linked glycosylation. ALG1 mutations cause a rare autosomal recessive disorder termed ALG1-CDG. To date 13 mutations in 18 patients from 14 families have been described with varying degrees of clinical severity. We identified and characterized 39 previously unreported cases of ALG1-CDG from 32 families and add 26 new mutations. Pathogenicity of each mutation was confirmed based on its inability to rescue impaired growth or hypoglycosylation of a standard biomarker in an alg1-deficient yeast strain. Using this approach we could not establish a rank order comparison of biomarker glycosylation and patient phenotype, but we identified mutations with a lethal outcome in the first two years of life. The recently identified protein-linked xeno-tetrasaccharide biomarker, NeuAc-Gal-GlcNAc2 , was seen in all 27 patients tested. Our study triples the number of known patients and expands the molecular and clinical correlates of this disorder.

Phenotyping GABA transaminase deficiency: a case description and literature review.

Gamma-aminobutyric acid transaminase (GABA-T) deficiency is an autosomal recessive disorder reported in only three unrelated families. It is caused by mutations in the ABAT gene, which encodes 4-aminobutyrate transaminase, an enzyme of GABA catabolism and mitochondrial nucleoside salvage. We report the case of a boy, deceased at 12 months of age, with early-onset epileptic encephalopathy, severe psychomotor retardation, hypotonia, lower-limb hyporeflexia, central hypoventilation, and rapid increase in weight and, to a lesser rate, length and head circumference. He presented signs of premature pubarche, thermal instability, and water-electrolyte imbalance. Serum total testosterone was elevated (43.3 ng/dl; normal range <16), as well as serum growth hormone (7.7 ng/ml; normal range <1). Brain magnetic resonance imaging (MRI) showed decreased myelination and generalized brain atrophy, later confirmed by post-mortem examination. ABAT gene sequencing was performed post-mortem, identifying a homozygous variant c.888G > T (p.Gln296His),not previously described. In vitro analysis concluded that this variant is pathogenic. The clinical features of this patient are similar to those reported so far in GABA-T deficiency. However, distinct mutations may have a different effect on enzymatic activity, which potentially could lead to a variable clinical outcome. Clinical investigation aiming for a diagnosis should not end with the patient's death, as it may allow a more precise genetic counselling for the family.

First two unrelated cases of isolated sedoheptulokinase deficiency: A benign disorder?

We present the first two reported unrelated patients with an isolated sedoheptulokinase (SHPK) deficiency. The first patient presented with neonatal cholestasis, hypoglycemia, and anemia, while the second patient presented with congenital arthrogryposis multiplex, multiple contractures, and dysmorphisms. Both patients had elevated excretion of erythritol and sedoheptulose, and each had a homozygous nonsense mutation in SHPK. SHPK is an enzyme that phosphorylates sedoheptulose to sedoheptulose-7-phosphate, which is an important intermediate of the pentose phosphate pathway. It is questionable whether SHPK deficiency is a causal factor for the clinical phenotypes of our patients. This study illustrates the necessity of extensive functional and clinical workup for interpreting a novel variant, including nonsense variants.

Guanidinoacetate methyltransferase (GAMT) deficiency: outcomes in 48 individuals and recommendations for diagnosis, treatment and monitoring.

We collected data on 48 patients from 38 families with guanidinoacetate methyltransferase (GAMT) deficiency. Global developmental delay/intellectual disability (DD/ID) with speech/language delay and behavioral problems as the most affected domains was present in 44 participants, with additional epilepsy present in 35 and movement disorder in 13. Treatment regimens included various combinations/dosages of creatine-monohydrate, l-ornithine, sodium benzoate and protein/arginine restricted diets. The median age at treatment initiation was 25.5 and 39 months in patients with mild and moderate DD/ID, respectively, and 11 years in patients with severe DD/ID. Increase of cerebral creatine and decrease of plasma/CSF guanidinoacetate levels were achieved by supplementation with creatine-monohydrate combined with high dosages of l-ornithine and/or an arginine-restricted diet (250 mg/kg/d l-arginine). Therapy was associated with improvement or stabilization of symptoms in all of the symptomatic cases. The 4 patients treated younger than 9 months had normal or almost normal developmental outcomes. One with inconsistent compliance had a borderline IQ at age 8.6 years. An observational GAMT database will be essential to identify the best treatment to reduce plasma guanidinoacetate levels and improve long-term outcomes.

A frequent splicing mutation and novel missense mutations color the updated mutational spectrum of classic galactosemia in Portugal.

Classic galactosemia is an autosomal recessive disorder caused by deficient galactose-1-phosphate uridylyltransferase (GALT) activity. Patients develop symptoms in the neonatal period, which can be ameliorated by dietary restriction of galactose. Many patients develop long-term complications, with a broad range of clinical symptoms whose pathophysiology is poorly understood. The high allelic heterogeneity of GALT gene that characterizes this disorder is thought to play a determinant role in biochemical and clinical phenotypes. We aimed to characterize the mutational spectrum of GALT deficiency in Portugal and to assess potential genotype-phenotype correlations. Direct sequencing of the GALT gene and in silico analyses were employed to evaluate the impact of uncharacterized mutations upon GALT functionality. Molecular characterization of 42 galactosemic Portuguese patients revealed a mutational spectrum comprising 14 nucleotide substitutions: ten missense, two nonsense and two putative splicing mutations. Sixteen different genotypic combinations were detected, half of the patients being p.Q188R homozygotes. Notably, the second most frequent variation is a splicing mutation. In silico predictions complemented by a close-up on the mutations in the protein structure suggest that uncharacterized missense mutations have cumulative point effects on protein stability, oligomeric state, or substrate binding. One splicing mutation is predicted to cause an alternative splicing event. This study reinforces the difficulty in establishing a genotype-phenotype correlation in classic galactosemia, a monogenic disease whose complex pathogenesis and clinical features emphasize the need to expand the knowledge on this "cloudy" disorder.

Antenatal manifestations of mitochondrial disorders.

Mitochondrial respiratory chain diseases are a heterogeneous group of pathologies caused by genetic alterations affecting mitochondrial energy production. Theoretically, this deficiency may lead to any symptoms, in any organ or tissue, at any age even before birth. The aim of our study was to identify the frequency and characterize antenatal manifestations identifying possible associations between mitochondrial disease and more specific and earlier manifestation. We retrospectively review the files of 44 paediatric subjects with genetic and biochemical alterations of respiratory chain identified in the first decade of life and compare data with a control group (n = 88). Our results show that maternal age was similar in both groups. The female gender was predominant in patients group. Gestational age at delivery was similar in both groups. Concerning birth weight, it was significantly lower (p = 0.001) in patients (2899.9 ± 538.3 vs. 3246.6 ± 460.2 g). Fifteen pregnancies of the patients group were considered abnormal. Our findings show that intrauterine growth restriction was the most frequent antenatal feature observed. Neonatal morbidity was significantly higher (fivefold) in patients (p < 0.001). The clinical findings are independent of the molecular defect type. Our results are preliminary and more studies are needed, in order to learn more about mitochondrial physiology and activity in embryological development for the assessment of mitochondrial disease progress in fetal life. However, the present work is a significant contribution, given the scarcity of information in this field.

Leukoencephalopathy with thalamus and brainstem involvement and high lactate 'LTBL' caused by EARS2 mutations.

In the large group of genetically undetermined infantile-onset mitochondrial encephalopathies, multiple defects of mitochondrial DNA-related respiratory-chain complexes constitute a frequent biochemical signature. In order to identify responsible genes, we used exome-next-generation sequencing in a selected cohort of patients with this biochemical signature. In an isolated patient, we found two mutant alleles for EARS2, the gene encoding mitochondrial glutamyl-tRNA synthetase. The brain magnetic resonance imaging of this patient was hallmarked by extensive symmetrical cerebral white matter abnormalities sparing the periventricular rim and symmetrical signal abnormalities of the thalami, midbrain, pons, medulla oblongata and cerebellar white matter. Proton magnetic resonance spectroscopy showed increased lactate. We matched this magnetic resonance imaging pattern with that of a cohort of 11 previously selected unrelated cases. We found mutations in the EARS2 gene in all. Subsequent detailed clinical and magnetic resonance imaging based phenotyping revealed two distinct groups: mild and severe. All 12 patients shared an infantile onset and rapidly progressive disease with severe magnetic resonance imaging abnormalities and increased lactate in body fluids and proton magnetic resonance spectroscopy. Patients in the 'mild' group partially recovered and regained milestones in the following years with striking magnetic resonance imaging improvement and declining lactate levels, whereas those of the 'severe' group were characterized by clinical stagnation, brain atrophy on magnetic resonance imaging and persistent lactate increases. This new neurological disease, early-onset leukoencephalopathy with thalamus and brainstem involvement and high lactate, is hallmarked by unique magnetic resonance imaging features, defined by a peculiar biphasic clinical course and caused by mutations in a single gene, EARS2, expanding the list of medically relevant defects of mitochondrial DNA translation.

Acute liver failure in under two year-olds--are there markers of metabolic disease on admission?

INTRODUCTION: The early establishment of an etiology for acute liver failure (ALF) in infants is essential for the start of adequate treatment in the shortest timeframe possible. AIM: To identify markers of inherited metabolic disease on admission in children under two years of age with ALF. MATERIAL AND METHODS: A retrospective review of the medical records of all children (< 2 years old) with ALF admitted to the pediatric hepatology or intensive care units of a tertiary center over a twenty-three year period (January 1989 to December 2011) was done. Patients were divided into two groups: with (group A) or without (group B) a metabolic etiology. Clinical and laboratory parameters on admission were compared. RESULTS: Twenty-three children met inclusion criteria. Twelve had ALF of metabolic origin (group A). The median age in this group was 2.25 (Q1-Q3: 0.63-4.65) months and in group B 8.0 (Q1-Q3: 1.5-15) months. History of failure to thrive and/or vomiting was more frequent in group A (p = 0.022). Age, gender, encephalopathy and left ventricular hypertrophy were similar in both groups (p = 0.147, p = 1.000, p = 0.637, p = 1.000, respectively). Laboratory tests on admission (plasma lactate, ammonia, cholesterol, phosphate, INR, glucose, bilirubin, ALT, base excess and the presence of reducing substances in urine) showed no statistically significant differences between groups. CONCLUSION: This study showed that although infants with inborn errors of metabolism showed a trend towards lower age at presentation, the only marker of inherited metabolic disease found on admission was history of vomiting and/or failure to thrive.

Pyridoxine-dependent epilepsy due to antiquitin deficiency: achieving a favourable outcome.

We report 4 pyridoxine-dependent epilepsy patients in which good outcome was determined in three. The 4 patients were male and aged from 7 to 24 years old (from three unrelated Caucasian families). A clinical diagnosis of neonatal pyridoxine-dependent epilepsy was confirmed by biochemical and genetic studies. Clinical evaluation was performed and medical records were reviewed for therapy implementation and management, neurodevelopment outcome, magnetic resonance imaging, and electroencephalography. All were taking pyridoxine treatment and were seizure-free. Elevated urinary alpha-aminoadipic semialdehyde excretion was found in all patients. Antiquitin gene analysis identified a large homozygous deletion in one patient and two heterozygous mutations in the others. Treatment with pyridoxine should be attempted for all cases of infantile and childhood refractory epilepsy, as has been the case over the last 20 years. Currently, urinary alpha-aminoadipic semialdehyde is a reliable biomarker of pyridoxine-dependent epilepsy, even under pyridoxine treatment. Detection of mutations in the antiquitin gene, encoding alpha-aminoadipic semialdehyde dehydrogenase, establishes the diagnosis and allows for adequate genetic counselling.