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Introduction Nonaccidental trauma (NAT) is considered when pediatric patients present with intracranial injuries and a negative history of an accidental injury or concomitant medical diagnosis. The evaluation of NAT should include the consideration of possible medical causes including coagulation, hematologic, metabolic and other genetic disorders, as well as witnessed and unwitnessed accidental injuries. Case Presentation We present a 7‐month‐old male with spells and incidental findings of bilateral subdural hematomas, retinal hemorrhages, and secondary macrocephaly, leading to investigation for NAT. Biochemical analysis showed excretion of a large amount of D‐2‐hydroxyglutaric in urine consistent with a biochemical diagnosis of D‐2‐hydroxyglutaric aciduria, a rare neurometabolic disorder characterized by developmental delay, epilepsy, hypotonia, and psychomotor retardation. None of these symptoms were present in our patient at the time of diagnosis. Molecular genetic testing revealed a pathogenic splice site variant (c.685‐2A>G) and a variant of uncertain significance (c.1256G>T) with evidence of pathogenicity in the D2HGDH gene, consistent with a molecular diagnosis of D‐2‐hydroxyglutaric aciduria type I (OMIM #600721). Conclusion Since several metabolic disorders, including D‐2‐hydroxyglutaric aciduria type I, can present solely with symptoms suggestive of NAT (subdural and retinal hemorrhages), an early metabolic evaluation by urine organic acid analysis should be included in clinical protocols evaluating NAT. A methodical and nonjudgmental approach coordinated between pediatricians and metabolic specialists is also necessary to ensure that rare genetic conditions are not overlooked to prevent devastating social, legal, and financial consequences of suspected child abuse.

Newborn screening (NBS) for Krabbe disease (KD) is performed by measurement of galactocerebrosidase (GALC) activity as the primary test. This revealed that GALC activity has poor specificity for KD. Psychosine (PSY) was proposed as a disease marker useful to reduce the false positive rate for NBS and for disease monitoring. We report a highly sensitive PSY assay that allows identification of KD patients with minimal PSY elevations. PSY was extracted from dried blood spots or erythrocytes with methanol containing d5-PSY as internal standard, and measured by liquid chromatography–tandem mass spectrometry. Analysis of PSY in samples from controls (N = 209), GALC pseudodeficiency carriers (N = 55), GALC pathogenic variant carriers (N = 27), patients with infantile KD (N = 26), and patients with late-onset KD (N = 11) allowed for the development of an effective laboratory screening and diagnostic algorithm. Additional longitudinal measurements were used to track therapeutic efficacy of hematopoietic stem cell transplantion (HSCT). This study supports PSY quantitation as a critical component of NBS for KD. It helps to differentiate infantile from later onset KD variants, as well as from GALC variant and pseudodeficiency carriers. Additionally, this study provides further data that PSY measurement can be useful to monitor KD progression before and after treatment.

Purpose To describe an efficient and effective multiplex screening strategy for sulfatide degradation disorders and mucolipidosis type II/III (MLII/III) using 3 mL of urine. Methods Glycosaminoglycans were analyzed by liquid chromatography-tandem mass spectrometry. Matrix assisted laser desorption/ionization-time of flight tandem mass spectrometry was used to identify free oligosaccharides and identify 22 ceramide trihexosides and 23 sulfatides, which are integrated by 670 calculated ratios. Collaborative Laboratory Integrated Reports (CLIR; https://clir.mayo.edu ) was used for post-analytical interpretation of the complex metabolite profile and to aid in the differential diagnosis of abnormal results. Results Multiplex analysis was performed on 25 sulfatiduria case samples and compiled with retrospective data from an additional 15 cases revealing unique patterns of biomarkers for each disorder of sulfatide degradation (MLD, MSD, and Saposin B deficiency) and for MLII/III, thus allowing the formulation of a novel algorithm for the biochemical diagnosis of these disorders. Conclusions Comprehensive and integrated urine screening could be very effective in the initial workup of patients suspected of having a lysosomal disorder as it covers disorders of sulfatide degradation and narrows down the differential diagnosis in patients with elevated glycosaminoglycans.

Phosphoglucomutase 1 (PGM1) catalyzes the interconversion of glucose-6-phosphate to glucose-1-phosphate and is a key enzyme of glycolysis, glycogenesis, and glycogenolysis. PGM1 deficiency (OMIM: 614921) was initially defined as a glycogen storage disorder (type XIV), and later re-classified as a PGM1-congenital disorder of glycosylation (PGM1-CDG). Serum transferrin (Tf) glycan isoform analysis by liquid chromatography-mass spectrometry (LC-MS) is used as a primary diagnostic screen tool, and reveals a very unique CDG profile described as a mixture of CDG-type I and CDG-type II patterns. Oral d-galactose supplementation shows significant clinical and metabolic improvements, which are indicated by the Tf glycan isoform normalization over time in patients with PGM1-CDG. Thus, there is a need for biomarkers to guide d-galactose dosage in patients in order to maintain effective and safe drug levels. Here, we present a simplified algorithm called PGM1-CDG Treatment Monitoring Index (PGM1-TMI) for assessing the response of PGM1-CDG patients to d-galactose supplementation. For our single-center cohort of 16 PGM1-CDG patients, the Tf glycan profile analysis provided the biochemical diagnosis in all of them. In addition, the PGM1-TMI was reduced in PGM1-CDG patients under d-galactose supplementation as compared with their corresponding values before treatment, indicating that glycosylation proceeds towards normalization. PGM1-TMI allows tracking Tf glycan isoform normalization over time when the patients are on d-galactose supplementation.

Enzyme-based newborn screening for Mucopolysaccharidosis type I (MPS I) has a high false-positive rate due to the prevalence of pseudodeficiency alleles, often resulting in unnecessary and costly follow up. The glycosaminoglycans (GAGs), dermatan sulfate (DS) and heparan sulfate (HS) are both substrates for &alpha, l-iduronidase (IDUA). These GAGs are elevated in patients with MPS I and have been shown to be promising biomarkers for both primary and second-tier testing. Since February 2016, we have measured DS and HS in 1213 specimens submitted on infants at risk for MPS I based on newborn screening. Molecular correlation was available for 157 of the tested cases. Samples from infants with MPS I confirmed by IDUA molecular analysis all had significantly elevated levels of DS and HS compared to those with confirmed pseudodeficiency and/or heterozygosity. Analysis of our testing population and correlation with molecular results identified few discrepant outcomes and uncovered no evidence of false-negative cases. We have demonstrated that blood spot GAGs analysis accurately discriminates between patients with confirmed MPS I and false-positive cases due to pseudodeficiency or heterozygosity and increases the specificity of newborn screening for MPS I.

Fatty acid transport and mitochondrial oxidation (FATMO) is a complex pathway that plays a major role in energy production during fasting or when illness and stressful situations require higher energy consumption. After long-chain fatty acids are mobilized from adipose tissue, taken up by liver and muscle cells, and activated to coenzyme A esters, they are transported into mitochondria by the sequential action of carnitine palmitoyltransferase (CPT) I, carnitineacylcarnitine translocase, and CPT II (Bonnefont et al., 1999). Fatty acids are then oxidized in a cyclic fashion by four sequential reactions, each catalyzed by one of multiple enzymes with overlapping substrate chainlength specificity: FAD-dependent acyl-CoA dehydrogenase, enoyl-CoA hydratase, NAD-dependent L-3hydroxyacyl-CoA dehydrogenase, and ketoacyl-CoA thiolase. Each cycle of the pathway produces a molecule of acetyl-CoA and a shortened fatty acid that re-enters the cycle until it is completely metabolized. In the liver, acetyl-CoA constitutes the building block for the synthesis of ketone bodies, which serve as fuels for production of energy in other tissues. Inherited FATMO disorders represent a rapidly expanding class of metabolic diseases (Bennett et al., 2000). Signs and symptoms may vary greatly in severity and typically include hypoketotic hypoglycemia, transient to fulminant liver disease, skeletal myopathy, cardiomyopathy, and sudden and unexpected death in early life. Symptoms may appear at any age, from birth to adult life, and in variable combinations, frequently leading to life-threatening episodes of metabolic decompensation. To date, all known FATMO disorders are inherited as autosomal recessive traits, with a recurrence risk of 25%. Although prenatal ‘screening’ could occasionally be informative (Nada et al., 1996; Chalmers et al., 1997), the pursuit of a prenatal diagnosis after an index case with an unspecified diagnosis should be limited to special circumstances, recommending instead aggressive preventive treatment and a thorough evaluation of the newborn immediately after birth. The prenatal diagnosis of FATMO disorders raises both ethical and medical issues. On one hand, parents face the option of abortion for a treatable disorder like MCAD deficiency or carnitine uptake defect, having experienced the sudden death of one or more children. At the other end of the clinical spectrum are disorders like glutaric acidemia type 2 with congenital anomalies and neonatal CPT II deficiency, characterized by very poor prognosis and outcome, and obvious candidates for prenatal diagnosis. Another unique aspect of prenatal diagnosis for FATMO disorders is the associated risk of maternal