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1.
medRxiv ; 2024 Apr 10.
Article in English | MEDLINE | ID: mdl-38645225

ABSTRACT

Pyruvate dehydrogenase complex deficiency (PDCD) is a disorder of mitochondrial metabolism that is caused by pathogenic variants in multiple genes, including PDHA1. Typical neonatal brain imaging findings in PDCD have been described, with a focus on malformative features and chronic encephaloclastic changes. However, fetal brain MRI imaging in confirmed PDCD has not been comprehensively described. We sought to demonstrate the prenatal neurological and systemic manifestations of PDCD determined by comprehensive fetal imaging and genomic sequencing. All fetuses with a diagnosis of genetic PDCD who had undergone fetal MRI were included in the study. Medical records, imaging data, and genetic testing results were reviewed and reported descriptively. Ten patients with diagnosis of PDCD were included. Most patients had corpus callosum dysgenesis, abnormal gyration pattern, reduced brain volumes, and periventricular cystic lesions. One patient had associated intraventricular hemorrhages. One patient had a midbrain malformation with aqueductal stenosis and severe hydrocephalus. Fetuses imaged in the second trimester were found to have enlargement of the ganglionic eminences with cystic cavitations, while those imaged in the third trimester had germinolytic cysts. Fetuses with PDCD have similar brain MRI findings to neonates described in the literature, although some of these findings may be subtle early in pregnancy. Additional features, such as cystic cavitations of the ganglionic eminences, are noted in the second trimester in fetuses with PDCD, and these may represent a novel early diagnostic marker for PDCD. Using fetal MRI to identify these radiological hallmarks to inform prenatal diagnosis of PDCD may guide genetic counseling, pregnancy decision-making, and neonatal care planning.

2.
J Mass Spectrom Adv Clin Lab ; 31: 49-58, 2024 Jan.
Article in English | MEDLINE | ID: mdl-38375486

ABSTRACT

Objectives: Ketone bodies (KBs) serve as important energy sources that spare glucose, providing the primary energy for cardiac muscle, skeletal muscle during aerobic exercise, and the brain during periods of catabolism. The levels and relationships between the KBs are critical indicators of metabolic health and disease. However, challenges in separating isomeric KBs and concerns about sample stability have previously limited their clinical measurement. Methods: A novel 6.5-minute liquid chromatography-mass spectrometry-based assay was developed, enabling the precise measurement of alpha-, beta- and gamma-hydroxybutyrate, beta-hydroxyisobutyrate, and acetoacetate. This method was fully validated for human serum and plasma samples by investigating extraction efficiency, matrix effects, accuracy, recovery, intra- and inter-precision, linearity, lower limit of quantitation (LLOQ), carryover, specificity, stability, and more. From 107 normal samples, reference ranges were established for all analytes and the beta-hydroxybutyrate/acetoacetate ratio. Results: All five analytes were adequately separated chromatographically. An extraction efficiency between 80 and 120 % was observed for all KBs. Accuracy was evaluated through spike and recovery using 10 random patient samples, with an average recovery of 85-115 % for all KBs and a coefficient of variation of ≤ 3 %. Coefficients of variation for intra- and inter-day imprecision were < 5 %, and the total imprecision was < 10 %. No significant interferences were observed. Specimens remained stable for up to 6 h on ice or 2 h at room temperature. Conclusions: The developed method is highly sensitive and robust. It has been validated for use with human serum and plasma, overcoming stability concerns and providing a reliable and efficient quantitative estimation of ketone bodies.

4.
Front Endocrinol (Lausanne) ; 14: 1268135, 2023.
Article in English | MEDLINE | ID: mdl-38027095

ABSTRACT

Timely diagnosis of persistent neonatal hypoglycemia is critical to prevent neurological sequelae, but diagnosis is complicated by the heterogenicity of the causes. We discuss two cases at separate institutions in which clinical management was fundamentally altered by the results of molecular genetic testing. In both patients, critical samples demonstrated hypoketotic hypoglycemia and a partial glycemic response to glucagon stimulation, thereby suggesting hyperinsulinism (HI). However, due to rapid genetic testing, both patients were found to have deoxyguanosine kinase (DGUOK)-related mitochondrial DNA depletion syndrome, an unexpected diagnosis. Patients with this disease typically present with either hepatocerebral disease in the neonatal period or isolated hepatic failure in infancy. The characteristic features involved in the hepatocerebral form of the disease include lactic acidosis, hypoglycemia, cholestasis, progressive liver failure, and increasing neurologic dysfunction. Those with isolated liver involvement experience hepatomegaly, cholestasis, and liver failure. Although liver transplantation is considered, research has demonstrated that for patients with DGUOK-related mitochondrial DNA depletion syndrome and neurologic symptoms, early demise occurs. Our report advocates for the prompt initiation of genetic testing in patients presenting with persistent neonatal hypoglycemia and for the incorporation of mitochondrial DNA depletion syndromes in the differential diagnosis of HI.


Subject(s)
Cholestasis , Hyperinsulinism , Hypoglycemia , Liver Failure , Humans , Infant, Newborn , DNA, Mitochondrial/genetics , Hypoglycemia/complications , Hypoglycemia/diagnosis , Hypoglycemia/genetics , Liver Failure/genetics , Mutation
5.
N Engl J Med ; 389(21): 1972-1978, 2023 Nov 23.
Article in English | MEDLINE | ID: mdl-37991855

ABSTRACT

Mahvash disease is an exceedingly rare genetic disorder of glucagon signaling characterized by hyperglucagonemia, hyperaminoacidemia, and pancreatic α-cell hyperplasia. Although there is no known definitive treatment, octreotide has been used to decrease systemic glucagon levels. We describe a woman who presented to our medical center after three episodes of small-volume hematemesis. She was found to have hyperglucagonemia and pancreatic hypertrophy with genetically confirmed Mahvash disease and also had evidence of portal hypertension (recurrent portosystemic encephalopathy and variceal hemorrhage) in the absence of cirrhosis. These findings established a diagnosis of portosinusoidal vascular disease, a presinusoidal type of portal hypertension previously known as noncirrhotic portal hypertension. Liver transplantation was followed by normalization of serum glucagon and ammonia levels, reversal of pancreatic hypertrophy, and resolution of recurrent encephalopathy and bleeding varices.


Subject(s)
Genetic Diseases, Inborn , Glucagon , Hypertension, Portal , Liver Transplantation , Female , Humans , Esophageal and Gastric Varices/etiology , Esophageal and Gastric Varices/surgery , Gastrointestinal Hemorrhage/etiology , Gastrointestinal Hemorrhage/surgery , Glucagon/blood , Glucagon/genetics , Hypertension, Portal/blood , Hypertension, Portal/etiology , Hypertension, Portal/genetics , Hypertension, Portal/surgery , Hypertrophy/genetics , Liver Cirrhosis , Genetic Diseases, Inborn/blood , Genetic Diseases, Inborn/diagnosis , Genetic Diseases, Inborn/genetics , Genetic Diseases, Inborn/surgery , Pancreatic Diseases/genetics , Pancreatic Diseases/pathology , Pancreatic Diseases/surgery , Glucagon-Secreting Cells/pathology
6.
Mol Genet Metab ; 140(1-2): 107710, 2023.
Article in English | MEDLINE | ID: mdl-37903659

ABSTRACT

Iron­sulfur clusters (FeS) are one of the most primitive and ubiquitous cofactors used by various enzymes in multiple pathways. Biosynthesis of FeS is a complex multi-step process that is tightly regulated and requires multiple machineries. IBA57, along with ISCA1 and ISCA2, play a role in maturation of [4Fe-4S] clusters which are required for multiple mitochondrial enzymes including mitochondrial Complex I, Complex II, lipoic acid synthase, and aconitase. Pathogenic variants in IBA57 have been associated with multiple mitochondrial dysfunctions syndrome 3 (MMDS3) characterized by infantile to early childhood-onset psychomotor regression, optic atrophy and nonspecific dysmorphism. Here we report a female proband who had prenatal involvement including IUGR and microcephaly and developed subacute psychomotor regression at the age of 5 weeks in the setting of preceding viral infection. Brain imaging revealed cortical malformation with polymicrogyria and abnormal signal alteration in brainstem and spinal cord. Biochemical analysis revealed increased plasma glycine and hyperexcretion of multiple organic acids in urine, raising the concern for lipoic acid biosynthesis defects and mitochondrial FeS assembly defects. Molecular analysis subsequently detected compound heterozygous variants in IBA57, confirming the diagnosis of MMDS3. Although the number of MMDS3 patients are limited, certain degree of genotype-phenotype correlation has been observed. Unusual brain imaging in the proband highlights the need to include mitochondrial disorders as differential diagnoses of structural brain abnormalities. Lastly, in addition to previously known biomarkers including high blood lactate and plasma glycine levels, the increase of 2-hydroxyadipic and 2-ketoadipic acids in urine organic acid analysis, in the appropriate clinical context, should prompt an evaluation for the lipoic acid biosynthesis defects and mitochondrial FeS assembly defects.


Subject(s)
Iron-Sulfur Proteins , Mitochondrial Diseases , Thioctic Acid , Humans , Child, Preschool , Female , Infant , Lysine/metabolism , Tryptophan/metabolism , Iron-Sulfur Proteins/genetics , Mitochondrial Diseases/diagnosis , Mitochondrial Diseases/genetics , Mitochondrial Diseases/metabolism , Mitochondria/genetics , Mitochondria/metabolism , Biomarkers/metabolism , Glycine/metabolism , Mitochondrial Proteins/genetics , Mitochondrial Proteins/metabolism , Carrier Proteins/genetics
7.
Neurotherapeutics ; 20(6): 1723-1745, 2023 Oct.
Article in English | MEDLINE | ID: mdl-37723406

ABSTRACT

We sought to prospectively characterize the nutritional status of adults ≥ 19 years (n = 22, 27% males) and children (n = 38, 61% male) with genetically-confirmed primary mitochondrial disease (PMD) to guide development of precision nutritional support strategies to be tested in future clinical trials. We excluded subjects who were exclusively tube-fed. Daily caloric requirements were estimated using World Health Organization (WHO) equations to predict resting energy expenditure (REE) multiplied by an activity factor (AF) based on individual activity levels. We developed a Mitochondrial Disease Activity Factors (MOTIVATOR) score to encompass the impact of muscle fatigue typical of PMD on physical activity levels. PMD cohort daily diet intake was estimated to be 1,143 ± 104.1 kcal in adults (mean ± SEM, 76.2% of WHO-MOTIVATOR predicted requirement), and 1,114 ± 62.3 kcal in children (86.4% predicted). A total of 11/22 (50%) adults and 18/38 (47.4%) children with PMD consumed ≤ 75% predicted daily Kcal needs. Malnutrition was identified in 16/60 (26.7%) PMD subjects. Increased protein and fat intake correlated with improved muscle strength in those with insufficient daily Kcal intake (≤ 75% predicted); higher protein and fat intake correlated with decreased muscle fatigue; and higher protein, fat, and carbohydrate intake correlated with improved quality of life (QoL). These data demonstrate the frequent occurrence of malnutrition in PMD and emphasize the critical need to devise nutritional interventions to optimize clinical outcomes.


Subject(s)
Malnutrition , Mitochondrial Diseases , Adult , Child , Humans , Male , Female , Nutritional Status , Quality of Life , Energy Intake , Muscle Fatigue , Energy Metabolism
8.
JIMD Rep ; 64(5): 367-374, 2023 Sep.
Article in English | MEDLINE | ID: mdl-37701333

ABSTRACT

Dihydrolipoamide dehydrogenase (DLD; E3) oxidizes lipoic acid. Restoring the oxidized state allows lipoic acid to act as a necessary electron sink for the four mitochondrial keto-acid dehydrogenases: pyruvate dehydrogenase, alpha-ketoglutarate dehydrogenase, branched-chain α-keto-acid dehydrogenase, and 2-oxoadipate dehydrogenase. DLD deficiency (DLDD) is caused by biallelic pathogenic variants in DLD. Three major forms have been described: encephalopathic, hepatic, and myopathic, although DLDD patients exhibit overlapping phenotypes. Hyperlactatemia, hyperexcretion of tricarboxylic acid cycle (TCA) metabolites and branched-chain keto acids, increased plasma branched-chain amino acids and allo-isoleucine are intermittent metabolic abnormalities reported in patients with DLDD. However, the diagnostic performance of these metabolites has never been studied. Therefore, we sought to systematically evaluate the diagnostic utility of these biomarkers for DLDD. We retrospectively analyzed the results of biochemical testing of six unrelated DLDD patients, including values obtained during both well visits and acute decompensation episodes. Elevation of branched-chain amino acid concentrations was not consistently observed. We found that five of six patients in our cohort had a maximum lifetime value of allo-isoleucine of 6 µmol/L, showing that alloisoleucine elevations even during illness may be subtle. Urine organic acid analysis (UOA) during acute decompensation episodes was abnormal in all cases; however, the pattern of abnormalities had high intersubject variability. No single biomarker was universally present, even in patients experiencing metabolic decompensation. We also observed novel biochemical associations: three patients had hyperexcretion of TCA cycle metabolites during crisis; in two patients, 2-ketoadipic and 2-hydroxyadipic acids, by products of lysine degradation, were detected. We propose that these result from 2-oxoadipate dehydrogenase deficiency, an underappreciated biochemical abnormality in DLD. Given the diversity of biochemical profiles among the patients with DLDD, we conclude that accurate biochemical diagnosis relies on a high index of suspicion and multipronged biochemical analysis, including both plasma amino acid and urine organic acid quantitation during decompensation. Biochemical diagnosis during the well state is challenging. We emphasize the critical importance of multiple simultaneous biochemical tests for diagnosis and monitoring of DLDD. We also highlight the under-recognized role of DLD in the lysine degradation pathway. Larger cohorts of patients are needed to establish a correlation between the biochemical pattern and clinical outcomes, as well as a genotype-phenotype correlation.

9.
Mol Syndromol ; 14(4): 303-309, 2023 Aug.
Article in English | MEDLINE | ID: mdl-37589028

ABSTRACT

Background: Pallister-Killian syndrome (PKS) is typically recognized by its features that include developmental delay, seizures, sparse temporal hair, and facial dysmorphisms. PKS is most frequently caused by mosaic supernumerary isochromosome 12p. Case Presentation: Here, we report a patient with PKS who was subsequently diagnosed with Burkitt lymphoma. Following the successful treatment of lymphoma, this patient demonstrated very mild intellectual disability despite the diagnosis of PKS, which is usually associated with severe developmental delay. Discussion: This is the first reported patient with PKS and a hematologic malignancy. Although there is no significant reported association of tetrasomy 12p with cancer, the co-occurrence of two rare findings in this patient suggests a potential relationship. The localization of AICDA, a gene for which overexpression has been implicated in promoting t(8;14) noted in our patient's lymphoma, raises a potential mechanism of pathogenesis. In addition, this case indicates that children with PKS can demonstrate near-normal cognitive development.

11.
JAMA Netw Open ; 6(5): e2312231, 2023 05 01.
Article in English | MEDLINE | ID: mdl-37155167

ABSTRACT

Importance: Newborn genome sequencing (NBSeq) can detect infants at risk for treatable disorders currently undetected by conventional newborn screening. Despite broad stakeholder support for NBSeq, the perspectives of rare disease experts regarding which diseases should be screened have not been ascertained. Objective: To query rare disease experts about their perspectives on NBSeq and which gene-disease pairs they consider appropriate to evaluate in apparently healthy newborns. Design, Setting, and Participants: This survey study, designed between November 2, 2021, and February 11, 2022, assessed experts' perspectives on 6 statements related to NBSeq. Experts were also asked to indicate whether they would recommend including each of 649 gene-disease pairs associated with potentially treatable conditions in NBSeq. The survey was administered between February 11 and September 23, 2022, to 386 experts, including all 144 directors of accredited medical and laboratory genetics training programs in the US. Exposures: Expert perspectives on newborn screening using genome sequencing. Main Outcomes and Measures: The proportion of experts indicating agreement or disagreement with each survey statement and those who selected inclusion of each gene-disease pair were tabulated. Exploratory analyses of responses by gender and age were conducted using t and χ2 tests. Results: Of 386 experts invited, 238 (61.7%) responded (mean [SD] age, 52.6 [12.8] years [range 27-93 years]; 126 [52.9%] women and 112 [47.1%] men). Among the experts who responded, 161 (87.9%) agreed that NBSeq for monogenic treatable disorders should be made available to all newborns; 107 (58.5%) agreed that NBSeq should include genes associated with treatable disorders, even if those conditions were low penetrance; 68 (37.2%) agreed that actionable adult-onset conditions should be sequenced in newborns to facilitate cascade testing in parents, and 51 (27.9%) agreed that NBSeq should include screening for conditions with no established therapies or management guidelines. The following 25 genes were recommended by 85% or more of the experts: OTC, G6PC, SLC37A4, CYP11B1, ARSB, F8, F9, SLC2A1, CYP17A1, RB1, IDS, GUSB, DMD, GLUD1, CYP11A1, GALNS, CPS1, PLPBP, ALDH7A1, SLC26A3, SLC25A15, SMPD1, GATM, SLC7A7, and NAGS. Including these, 42 gene-disease pairs were endorsed by at least 80% of experts, and 432 genes were endorsed by at least 50% of experts. Conclusions and Relevance: In this survey study, rare disease experts broadly supported NBSeq for treatable conditions and demonstrated substantial concordance regarding the inclusion of a specific subset of genes in NBSeq.


Subject(s)
Chondroitinsulfatases , Rare Diseases , Male , Adult , Humans , Infant, Newborn , Female , Middle Aged , Aged , Aged, 80 and over , Rare Diseases/diagnosis , Rare Diseases/genetics , Neonatal Screening , Parents , Amino Acid Transport System y+L , Monosaccharide Transport Proteins , Antiporters
12.
Genet Med ; 25(9): 100897, 2023 09.
Article in English | MEDLINE | ID: mdl-37191094

ABSTRACT

PURPOSE: Mendelian etiologies for acute encephalopathies in previously healthy children are poorly understood, with the exception of RAN binding protein 2 (RANBP2)-associated acute necrotizing encephalopathy subtype 1 (ANE1). We provide clinical, genetic, and neuroradiological evidence that biallelic variants in ribonuclease inhibitor (RNH1) confer susceptibility to a distinctive ANE subtype. METHODS: This study aimed to evaluate clinical data, neuroradiological studies, genomic sequencing, and protein immunoblotting results in 8 children from 4 families who experienced acute febrile encephalopathy. RESULTS: All 8 healthy children became acutely encephalopathic during a viral/febrile illness and received a variety of immune modulation treatments. Long-term outcomes varied from death to severe neurologic deficits to normal outcomes. The neuroradiological findings overlapped with ANE but had distinguishing features. All affected children had biallelic predicted damaging variants in RNH1: a subset that was studied had undetectable RNH1 protein. Incomplete penetrance of the RNH1 variants was evident in 1 family. CONCLUSION: Biallelic variants in RNH1 confer susceptibility to a subtype of ANE (ANE2) in previously healthy children. Intensive immunological treatments may alter outcomes. Genomic sequencing in children with unexplained acute febrile encephalopathy can detect underlying genetic etiologies, such as RNH1, and improve outcomes in the probands and at-risk siblings.


Subject(s)
Acute Febrile Encephalopathy , Brain Diseases , Leukoencephalitis, Acute Hemorrhagic , Child , Humans , Leukoencephalitis, Acute Hemorrhagic/diagnosis , Leukoencephalitis, Acute Hemorrhagic/genetics , Inflammasomes , Brain Diseases/genetics , Transcription Factors , Ribonucleases , Carrier Proteins
14.
Clin Chem ; 69(6): 564-582, 2023 06 01.
Article in English | MEDLINE | ID: mdl-37099687

ABSTRACT

BACKGROUND: Mitochondria are cytosolic organelles within most eukaryotic cells. Mitochondria generate the majority of cellular energy in the form of adenosine triphosphate (ATP) through oxidative phosphorylation (OxPhos). Pathogenic variants in mitochondrial DNA (mtDNA) and nuclear DNA (nDNA) lead to defects in OxPhos and physiological malfunctions (Nat Rev Dis Primer 2016;2:16080.). Patients with primary mitochondrial disorders (PMD) experience heterogeneous symptoms, typically in multiple organ systems, depending on the tissues affected by mitochondrial dysfunction. Because of this heterogeneity, clinical diagnosis is challenging (Annu Rev Genomics Hum Genet 2017;18:257-75.). Laboratory diagnosis of mitochondrial disease depends on a multipronged analysis that can include biochemical, histopathologic, and genetic testing. Each of these modalities has complementary strengths and limitations in diagnostic utility. CONTENT: The primary focus of this review is on diagnosis and testing strategies for primary mitochondrial diseases. We review tissue samples utilized for testing, metabolic signatures, histologic findings, and molecular testing approaches. We conclude with future perspectives on mitochondrial testing. SUMMARY: This review offers an overview of the current biochemical, histologic, and genetic approaches available for mitochondrial testing. For each we review their diagnostic utility including complementary strengths and weaknesses. We identify gaps in current testing and possible future avenues for test development.


Subject(s)
Mitochondria , Mitochondrial Diseases , Humans , Electron Transport , Mitochondria/genetics , Mitochondrial Diseases/diagnosis , Mitochondrial Diseases/genetics , DNA, Mitochondrial/genetics , Oxidative Phosphorylation
15.
Genet Med ; 25(2): 100332, 2023 02.
Article in English | MEDLINE | ID: mdl-36520152

ABSTRACT

PURPOSE: This study aimed to establish the genetic cause of a novel autosomal recessive neurodevelopmental disorder characterized by global developmental delay, movement disorder, and metabolic abnormalities. METHODS: We performed a detailed clinical characterization of 4 unrelated individuals from consanguineous families with a neurodevelopmental disorder. We used exome sequencing or targeted-exome sequencing, cosegregation, in silico protein modeling, and functional analyses of variants in HEK293 cells and Drosophila melanogaster, as well as in proband-derived fibroblast cells. RESULTS: In the 4 individuals, we identified 3 novel homozygous variants in oxoglutarate dehydrogenase (OGDH) (NM_002541.3), which encodes a subunit of the tricarboxylic acid cycle enzyme α-ketoglutarate dehydrogenase. In silico homology modeling predicts that c.566C>T:p.(Pro189Leu) and c.890C>A:p.(Ser297Tyr) variants interfere with the structure and function of OGDH. Fibroblasts from individual 1 showed that the p.(Ser297Tyr) variant led to a higher degradation rate of the OGDH protein. OGDH protein with p.(Pro189Leu) or p.(Ser297Tyr) variants in HEK293 cells showed significantly lower levels than the wild-type protein. Furthermore, we showed that expression of Drosophila Ogdh (dOgdh) carrying variants homologous to p.(Pro189Leu) or p.(Ser297Tyr), failed to rescue developmental lethality caused by loss of dOgdh. SpliceAI, a variant splice predictor, predicted that the c.935G>A:p.(Arg312Lys)/p.(Phe264_Arg312del) variant impacts splicing, which was confirmed through a mini-gene assay in HEK293 cells. CONCLUSION: We established that biallelic variants in OGDH cause a neurodevelopmental disorder with metabolic and movement abnormalities.


Subject(s)
Movement Disorders , Neurodevelopmental Disorders , Animals , Humans , Drosophila melanogaster/genetics , Drosophila melanogaster/metabolism , HEK293 Cells , Ketoglutarate Dehydrogenase Complex/genetics , Ketoglutarate Dehydrogenase Complex/metabolism , Neurodevelopmental Disorders/genetics
16.
Genet Med ; 25(6): 100314, 2023 06.
Article in English | MEDLINE | ID: mdl-36305855

ABSTRACT

PURPOSE: This study aimed to define the genotypic and phenotypic spectrum of reversible acute liver failure (ALF) of infancy resulting from biallelic pathogenic TRMU variants and determine the role of cysteine supplementation in its treatment. METHODS: Individuals with biallelic (likely) pathogenic variants in TRMU were studied within an international retrospective collection of de-identified patient data. RESULTS: In 62 individuals, including 30 previously unreported cases, we described 47 (likely) pathogenic TRMU variants, of which 17 were novel, and 1 intragenic deletion. Of these 62 individuals, 42 were alive at a median age of 6.8 (0.6-22) years after a median follow-up of 3.6 (0.1-22) years. The most frequent finding, occurring in all but 2 individuals, was liver involvement. ALF occurred only in the first year of life and was reported in 43 of 62 individuals; 11 of whom received liver transplantation. Loss-of-function TRMU variants were associated with poor survival. Supplementation with at least 1 cysteine source, typically N-acetylcysteine, improved survival significantly. Neurodevelopmental delay was observed in 11 individuals and persisted in 4 of the survivors, but we were unable to determine whether this was a primary or a secondary consequence of TRMU deficiency. CONCLUSION: In most patients, TRMU-associated ALF was a transient, reversible disease and cysteine supplementation improved survival.


Subject(s)
Liver Failure, Acute , Liver Failure , Adolescent , Child , Child, Preschool , Humans , Infant , Young Adult , Acetylcysteine/therapeutic use , Liver Failure/drug therapy , Liver Failure/genetics , Liver Failure, Acute/drug therapy , Liver Failure, Acute/genetics , Mitochondrial Proteins/genetics , Mutation , Retrospective Studies , tRNA Methyltransferases/genetics
17.
Mol Genet Metab Rep ; 33: 100931, 2022 Dec.
Article in English | MEDLINE | ID: mdl-36420423

ABSTRACT

Malate dehydrogenases (MDH) serve a critical role in maintaining equilibrium of the NAD+/NADH ratio between the mitochondria and cytosol through the catalysis of the oxidation of L-malate to oxaloacetate in a reversible, NADH-dependent manner. MDH2 encodes the mitochondrial isoform, which is integral to the tricarboxylic acid cycle and thus energy homeostasis. Recently, five patients harboring compound heterozygous MDH2 variants have been described, three with early-onset epileptic encephalopathy, one with a stroke-like episode, and one with dilated cardiomyopathy. Here, we describe an additional seven patients with biallelic variants in MDH2, the largest and most neurodevelopmentally and ethnically diverse cohort to-date, including homozygous variants, a sibling pair, non-European patients, and an adult. From these patients, we learn that MDH2 deficiency results in a biochemical signature including elevations of plasma lactate and the lactate:pyruvate ratio with urinary excretion of malate. It also results in a recognizable constellation of neuroimaging findings of anterior-predominant cerebral atrophy, subependymal cysts with ventricular septations. We also recognize MDH2 deficiency as a cause of Leigh syndrome. Taken with existing patient reports, we conclude that MDH2 deficiency is an emerging and likely under-recognized cause of infantile epileptic encephalopathy and provide a framework for medical evaluation of patients identified with biallelic MDH2 variants.

18.
N Engl J Med ; 387(15): 1395-1403, 2022 10 13.
Article in English | MEDLINE | ID: mdl-36239646

ABSTRACT

We describe the case of identical twin boys who presented with low body weight despite excessive caloric intake. An evaluation of their fibroblasts showed elevated oxygen consumption and decreased mitochondrial membrane potential. Exome analysis revealed a de novo heterozygous variant in ATP5F1B, which encodes the ß subunit of mitochondrial ATP synthase (also called complex V). In yeast, mutations affecting the same region loosen coupling between the proton motive force and ATP synthesis, resulting in high rates of mitochondrial respiration. Expression of the mutant allele in human cell lines recapitulates this phenotype. These data support an autosomal dominant mitochondrial uncoupling syndrome with hypermetabolism. (Funded by the National Institutes of Health.).


Subject(s)
Mitochondrial Diseases , Mitochondrial Proton-Translocating ATPases , Oxidative Phosphorylation , Oxygen Consumption , Humans , Male , Adenosine Triphosphate/metabolism , Diseases in Twins/genetics , Diseases in Twins/metabolism , Fibroblasts/metabolism , Mitochondria/metabolism , Mitochondrial Diseases/congenital , Mitochondrial Diseases/genetics , Mitochondrial Diseases/metabolism , Mitochondrial Proton-Translocating ATPases/genetics , Mitochondrial Proton-Translocating ATPases/metabolism , Mutation , Oxygen Consumption/genetics , Oxygen Consumption/physiology , Twins, Monozygotic/genetics
19.
Mol Genet Metab ; 137(3): 230-238, 2022 11.
Article in English | MEDLINE | ID: mdl-36182714

ABSTRACT

In this retrospective cohort study of 193 consecutive subjects with primary mitochondrial disease (PMD) seen at the Children's Hospital of Philadelphia Mitochondrial Medicine Frontier Program, we assessed prevalence, severity, and time of onset of sensorineural hearing loss (SNHL) for PMD cases with different genetic etiologies. Subjects were grouped by genetic diagnosis: mitochondrial DNA (mtDNA) pathogenic variants, single large-scale mtDNA deletions (SLSMD), or nuclear DNA (nDNA) pathogenic variants. SNHL was audiometrically confirmed in 27% of PMD subjects (20% in mtDNA pathogenic variants, 58% in SLSMD and 25% in nDNA pathogenic variants). SLSMD had the highest odds ratio for SNHL. SNHL onset was post-lingual in 79% of PMD cases, interestingly including all cases with mtDNA pathogenic variants and SLSMD, which was significantly different from PMD cases caused by nDNA pathogenic variants. SNHL onset during school age was predominant in this patient population. Regular audiologic assessment is important for PMD patients, and PMD of mtDNA etiology should be considered as a differential diagnosis in pediatric patients and young adults with post-lingual SNHL onset, particularly in the setting of multi-system clinical involvement. Pathogenic mtDNA variants and SLSMD are less likely etiologies in subjects with congenital, pre-lingual onset SNHL.


Subject(s)
Hearing Loss, Sensorineural , Mitochondrial Diseases , Young Adult , Humans , Child , DNA, Mitochondrial/genetics , Retrospective Studies , Mitochondrial Diseases/complications , Mitochondrial Diseases/genetics , Hearing Loss, Sensorineural/genetics , Hearing Loss, Sensorineural/diagnosis , Mitochondria/genetics
20.
Am J Med Genet A ; 188(11): 3312-3317, 2022 11.
Article in English | MEDLINE | ID: mdl-35972040

ABSTRACT

Sphingosine Lyase Insufficiency Syndrome (SPLIS) or SGPL1 Deficiency is a newly described entity that is characterized by steroid-resistant nephrotic syndrome, primary adrenal insufficiency, lymphopenia, ichthyosis, and/or endocrine and neurologic abnormalities. The earliest identification of SGPL1 pathogenic variants in association with this syndrome was reported in 2017. Since then, at least 36 patients have been reported with this pediatric syndrome. Here, we report a new patient with SPLIS who had a prenatal finding of adrenal calcifications, congenital nephrotic syndrome, and abnormal newborn screening concerning for Severe Combined Immunodeficiency. We conclude that SPLIS is a clinically recognizable condition with prenatal onset. This case should increase awareness of SPLIS in the differential diagnosis for adrenal calcifications. We present a case on the severe end of the clinical spectrum of SPLIS, and a review of the literature.


Subject(s)
Adrenal Gland Diseases , Adrenal Insufficiency , Calcinosis , Lyases , Nephrotic Syndrome , Adrenal Insufficiency/diagnosis , Adrenal Insufficiency/genetics , Aldehyde-Lyases/genetics , Calcinosis/diagnosis , Calcinosis/genetics , Child , Female , Humans , Infant, Newborn , Nephrotic Syndrome/pathology , Pregnancy , Sphingosine , Steroids , Syndrome
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