The use of ketogenic diets in children living with drug-resistant epilepsy, glucose transporter 1 deficiency syndrome and pyruvate dehydrogenase deficiency: A scoping review.

BACKGROUND: The ketogenic diet (KD) is a high fat, moderate protein and very low carbohydrate diet. It can be used as a medical treatment for drug-resistant epilepsy (DRE), glucose transporter 1 deficiency syndrome and pyruvate dehydrogenase deficiency. The aim of this scoping review was to map the KD literature, with a focus on epilepsy and associated metabolic conditions, to summarise the current evidence-base and identify any gaps. METHODS: This review was conducted using JBI scoping review methodological guidance and the PRISMA extension for scoping reviews reporting guidance. A comprehensive literature search was conducted in September 2021 and updated in February 2024 using MEDLINE, CINAHL, AMED, EmBASE, CAB Abstracts, Scopus and Food Science Source databases. RESULTS: The initial search yielded 2721 studies and ultimately, data were extracted from 320 studies that fulfilled inclusion criteria for the review. There were five qualitative studies, and the remainder were quantitative, including 23 randomised controlled trials (RCTs) and seven quasi-experimental studies. The USA published the highest number of KD studies followed by China, South Korea and the UK. Most studies focused on the classical KD and DRE. The studies key findings suggest that the KD is efficacious, safe and tolerable. CONCLUSIONS: There are opportunities available to expand the scope of future KD research, particularly to conduct high-quality RCTs and further qualitative research focused on the child's needs and family support to improve the effectiveness of KDs.

Metabolic epilepsies amenable to ketogenic therapies: Indications, contraindications, and underlying mechanisms.

Metabolic epilepsies arise in the context of rare inborn errors of metabolism (IEM), notably glucose transporter type 1 deficiency syndrome, succinic semialdehyde dehydrogenase deficiency, pyruvate dehydrogenase complex deficiency, nonketotic hyperglycinemia, and mitochondrial cytopathies. A common feature of these disorders is impaired bioenergetics, which through incompletely defined mechanisms result in a wide spectrum of neurological symptoms, such as epileptic seizures, developmental delay, and movement disorders. The ketogenic diet (KD) has been successfully utilized to treat such conditions to varying degrees. While the mechanisms underlying the clinical efficacy of the KD in IEM remain unclear, it is likely that the proposed heterogeneous targets influenced by the KD work in concert to rectify or ameliorate the downstream negative consequences of genetic mutations affecting key metabolic enzymes and substrates-such as oxidative stress and cell death. These beneficial effects can be broadly grouped into restoration of impaired bioenergetics and synaptic dysfunction, improved redox homeostasis, anti-inflammatory, and epigenetic activity. Hence, it is conceivable that the KD might prove useful in other metabolic disorders that present with epileptic seizures. At the same time, however, there are notable contraindications to KD use, such as fatty acid oxidation disorders. Clearly, more research is needed to better characterize those metabolic epilepsies that would be amenable to ketogenic therapies, both experimentally and clinically. In the end, the expanded knowledge base will be critical to designing metabolism-based treatments that can afford greater clinical efficacy and tolerability compared to current KD approaches, and improved long-term outcomes for patients.

Distinguishing Encephaloclastic Lesions Resulting From Primary or Secondary Pyruvate Dehydrogenase Deficiency From Other Neonatal or Infantile Cavitary Brain Lesions.

The central nervous system (CNS) is a highly complex and energy-dependent organ that is subject to a wide variety of metabolic, hypoxic-ischemic, and infectious insults that result in cystic changes. Diagnosis of metabolic defects causing extensive cystic changes is particularly challenging for the pediatric pathologist, due to the rarity of these conditions. Pyruvate dehydrogenase (PDH) deficiency is one of the most common etiologies of congenital lactic acidosis, caused by mutations in subunits of the large mitochondrial matrix complex, and characterized by periventricular cysts, although few detailed reports focusing on neuropathologic findings exist. In addition, rare defects in other mitochondrial enzymes such as short-chain enoyl-CoA hydratase (SCEH, encoded by ECHS1 gene) can cause secondary PDH deficiency and present with neonatal lactic acidosis, but neuropathological findings have never been reported. Nonmetabolic conditions can also produce CNS cystic lesions, primarily in newborns. The pathologist must therefore distinguish between these etiologically disparate conditions which can produce CNS cavitary lesions. Here, we compare and contrast the gross and microscopic findings of cysts associated with cases of PDH and SCEH deficiencies with other neonatal cystic brain diseases including periventricular leukomalacia, neonatal Alexander disease, Canavan disease, and a case of cysts associated with a vascular abnormality. Our studies show that PDH and SCEH deficiencies are not grossly or histologically distinguishable from each other and both are associated with smooth-walled cysts largely limited to the telencephalic germinal matrix. Both show an absence of prominent hemosiderin deposits, Rosenthal fibers, vacuolization of the white matter, and gliosis or axonal damage in the surrounding parenchyma. These features can help distinguish PDH/SCEH deficiency from other pediatric/neonatal cystic CNS disorders, especially those produced by hypoxic ischemic conditions. Cysts, usually bilateral, confined to the telencephalic germinal matrix should elicit metabolic and genetic testing to appropriately diagnose PDH and SCEH and distinguish them from each other.

Pyruvate dehydrogenase complex deficiency is linked to regulatory loop disorder in the αV138M variant of human pyruvate dehydrogenase.

The pyruvate dehydrogenase multienzyme complex (PDHc) connects glycolysis to the tricarboxylic acid cycle by producing acetyl-CoA via the decarboxylation of pyruvate. Because of its pivotal role in glucose metabolism, this complex is closely regulated in mammals by reversible phosphorylation, the modulation of which is of interest in treating cancer, diabetes, and obesity. Mutations such as that leading to the αV138M variant in pyruvate dehydrogenase, the pyruvate-decarboxylating PDHc E1 component, can result in PDHc deficiency, an inborn error of metabolism that results in an array of symptoms such as lactic acidosis, progressive cognitive and neuromuscular deficits, and even death in infancy or childhood. Here we present an analysis of two X-ray crystal structures at 2.7-Å resolution, the first of the disease-associated human αV138M E1 variant and the second of human wildtype (WT) E1 with a bound adduct of its coenzyme thiamin diphosphate and the substrate analogue acetylphosphinate. The structures provide support for the role of regulatory loop disorder in E1 inactivation, and the αV138M variant structure also reveals that altered coenzyme binding can result in such disorder even in the absence of phosphorylation. Specifically, both E1 phosphorylation at αSer-264 and the αV138M substitution result in disordered loops that are not optimally oriented or available to efficiently bind the lipoyl domain of PDHc E2. Combined with an analysis of αV138M activity, these results underscore the general connection between regulatory loop disorder and loss of E1 catalytic efficiency.

LIPT1 deficiency presenting as early infantile epileptic encephalopathy, Leigh disease, and secondary pyruvate dehydrogenase complex deficiency.

Lipoic acid is an essential cofactor for the mitochondrial 2-ketoacid dehydrogenase complexes and the glycine cleavage system. Lipoyltransferase 1 catalyzes the covalent attachment of lipoate to these enzyme systems. Pathogenic variants in LIPT1 gene have recently been described in four patients from three families, commonly presenting with severe lactic acidosis resulting in neonatal death and/or poor neurocognitive outcomes. We report a 2-month-old male with severe lactic acidosis, refractory status epilepticus, and brain imaging suggestive of Leigh disease. Exome sequencing implicated compound heterozygous LIPT1 pathogenic variants. We describe the fifth case of LIPT1 deficiency, whose phenotype progressed to that of an early infantile epileptic encephalopathy, which is novel compared to previously described patients whom we will review. Due to the significant biochemical and phenotypic overlap that LIPT1 deficiency and mitochondrial energy cofactor disorders have with pyruvate dehydrogenase deficiency and/or nonketotic hyperglycinemia, they are and have been presumptively under-diagnosed without exome sequencing.

In vivo metabolic flux profiling with stable isotopes discriminates sites and quantifies effects of mitochondrial dysfunction in C. elegans.

UNLABELLED: Mitochondrial respiratory chain (RC) disease diagnosis is complicated both by an absence of biomarkers that sufficiently divulge all cases and limited capacity to quantify adverse effects across intermediary metabolism. We applied high performance liquid chromatography (HPLC) and mass spectrometry (MS) studies of stable-isotope based precursor-product relationships in the nematode, C. elegans, to interrogate in vivo differences in metabolic flux among distinct genetic models of primary RC defects and closely related metabolic disorders. METHODS: C. elegans strains studied harbor single nuclear gene defects in complex I, II, or III RC subunits (gas-1, mev-1, isp-1); enzymes involved in coenzyme Q biosynthesis (clk-1), the tricarboxylic acid cycle (TCA, idh-1), or pyruvate metabolism (pdha-1); and central nodes of the nutrient-sensing signaling network that involve insulin response (daf-2) or the sirtuin homologue (sir-2.1). Synchronous populations of 2000 early larval stage worms were fed standard Escherichia coli on nematode growth media plates containing 1,6-(13)C2-glucose throughout their developmental period, with samples extracted on the first day of adult life in 4% perchloric acid with an internal standard. Quantitation of whole animal free amino acid concentrations and isotopic incorporation into amino and organic acids throughout development was performed in all strains by HPLC and isotope ratio MS, respectively. GC/MS analysis was also performed to quantify absolute isotopic incorporation in all molecular species of key TCA cycle intermediates in gas-1 and N2 adult worms. RESULTS: Genetic mutations within different metabolic pathways displayed distinct metabolic profiles. RC complex I (gas-1) and III (isp-1) subunit mutants, together with the coenzyme Q biosynthetic mutant (clk-1), shared a similar amino acid profile of elevated alanine and decreased glutamate. The metabolic signature of the complex II mutant (mev-1) was distinct from that of the other RC mutants but resembled that of the TCA cycle mutant (idh-1) and both signaling mutants (daf-2 and sir-2.1). All branched chain amino acid levels were significantly increased in the complex I and III mutants but decreased in the PDH mutant (pdha-1). The RC complex I, coenzyme Q, TCA cycle, and PDH mutants shared significantly increased relative enrichment of lactate+1 and absolute concentration of alanine+1, while glutamate+1 enrichment was significantly decreased uniquely in the RC mutants. Relative intermediary flux analyses were suggestive of proximal TCA cycle disruption in idh-1, completely reduced TCA cycle flux in sir-2.1, and apparent distal TCA cycle alteration in daf-2. GC/MS analysis with universally-labeled (13)C-glucose in adult worms further showed significantly increased isotopic enrichment in lactate, citrate, and malate species in the complex I (gas-1) mutant. CONCLUSIONS: Stable isotopic/mass spectrometric analysis can sensitively discriminate primary RC dysfunction from genetic deficiencies affecting either the TCA cycle or pyruvate metabolism. These data are further suggestive that metabolic flux analysis using stable isotopes may offer a robust means to discriminate and quantify the secondary effects of primary RC dysfunction across intermediary metabolism.

Imaging brain glucose metabolism in vivo reveals propionate as a major anaplerotic substrate in pyruvate dehydrogenase deficiency.

A vexing problem in mitochondrial medicine is our limited capacity to evaluate the extent of brain disease in vivo. This limitation has hindered our understanding of the mechanisms that underlie the imaging phenotype in the brain of patients with mitochondrial diseases and our capacity to identify new biomarkers and therapeutic targets. Using comprehensive imaging, we analyzed the metabolic network that drives the brain structural and metabolic features of a mouse model of pyruvate dehydrogenase deficiency (PDHD). As the disease progressed in this animal, in vivo brain glucose uptake and glycolysis increased. Propionate served as a major anaplerotic substrate, predominantly metabolized by glial cells. A combination of propionate and a ketogenic diet extended lifespan, improved neuropathology, and ameliorated motor deficits in these animals. Together, intermediary metabolism is quite distinct in the PDHD brain-it plays a key role in the imaging phenotype, and it may uncover new treatments for this condition.

Long-term use of investigational ß-Hydroxybutyrate salts in children with multiple acyl-CoA dehydrogenase or pyruvate dehydrogenase deficiency.

Several disorders of energy metabolism have been treated with exogenous ketone bodies. The benefit of this treatment is best documented in multiple acyl-CoA dehydrogenase deficiency (MADD) (MIM#231680). One might also expect ketone bodies to help in other disorders with impaired ketogenesis or in conditions that profit from a ketogenic diet. Here, we report the use of a novel preparation of dextro-ß-hydroxybutyrate (D-ßHB) salts in two cases of MADD and one case of pyruvate dehydrogenase (PDH) deficiency (MIM#312170). The two patients with MADD had previously been on a racemic mixture of D- and L­sodium hydroxybutyrate. Patient #1 found D-ßHB more palatable, and the change in formulation corrected hypernatraemia in patient #2. The patient with PDH deficiency was on a ketogenic diet but had not previously been given hydroxybutyrate. In this case, the addition of D-ßHB improved ketosis. We conclude that NHS101 is a good candidate for further clinical studies in this group of diseases of inborn errors of metabolism.

Mitochondrial respiratory chain disease discrimination by retrospective cohort analysis of blood metabolites.

UNLABELLED: Diagnosing primary mitochondrial respiratory chain (RC) dysfunction has long relied on invasive tissue biopsies, since no blood-based biomarker has been shown to have sufficiently high sensitivity and specificity across the myriad of individual clinical presentations. We sought to determine whether cohort-level evaluation of commonly obtained blood analytes might reveal consistent patterns to discriminate a heterogenous group of primary mitochondrial RC disease subjects both from control individuals and from subjects with pyruvate dehydrogenase deficiency. METHODS: Following IRB approval, 62 biochemical analyte concentrations or ratios were retrospectively analyzed in three well-defined and intentionally heterogeneous subject cohorts reflective of clinical practice: [1] Primary mitochondrial disease (n=19); [2] pyruvate dehydrogenase deficiency (n=4); and [3] controls (n=27). Blood analyte categories included comprehensive chemistry profile, creatine kinase, lipoprotein profile, lactate, pyruvate, and plasma amino acid profile. Non-parametric analyses were used to compare the median of each analyte level between cohorts. RESULTS: Disease cohorts differed significantly in their median levels of triglycerides, lactate, pyruvate, and multiple individual plasma amino acids. Primary mitochondrial disease was significantly discriminated at the cohort level from pyruvate dehydrogenase deficiency by greater pyruvate and alanine elevation in pyruvate dehydrogenase deficiency, as well as significantly increased branched chain amino acid (BCAA) levels and increased ratios of individual BCAAs to glutamate in mitochondrial disease. In addition, significant elevation of median blood triglyceride level was seen in the primary mitochondrial disease cohort. CONCLUSIONS: Blood metabolite profile analysis can discriminate a heterogeneous cohort of primary mitochondrial disease both from controls and from pyruvate dehydrogenase deficiency. Elevated BCAA levels, either absolutely or when considered relative to the level of glutamate, are common metabolic sequelae of primary mitochondrial RC disease. Prospective study is needed to validate observed plasma metabolite alterations as a potential biomarker of disease both in larger cohorts and at the individual subject level.

Ketogenic diet in action: Metabolic profiling of pyruvate dehydrogenase deficiency.

The pyruvate dehydrogenase complex serves as the main connection between cytosolic glycolysis and the tricarboxylic acid cycle within mitochondria. An infant with pyruvate dehydrogenase complex deficiency was treated with vitamin B1 supplementation and a ketogenic diet. These dietary modifications resolved the renal tubular reabsorption, central apnea, and transfusion-dependent anemia. A concurrent metabolome analysis demonstrated the resolution of the amino aciduria and an increased total amount of substrates in the tricarboxylic acid cycle, reflecting the improved mitochondrial energetics. Glutamate was first detected in the cerebrospinal fluid, accompanied by a clinical improvement, after the ketogenic ratio was increased to 3:1; thus, glutamate levels in cerebrospinal fluid may represent a biomarker for neuronal recovery. Metabolomic analyses of body fluids are useful for monitoring therapeutic effects in infants with inborn errors of carbohydrate metabolism.

Potential role of stress-induced gluconeogenesis in disease aggravation and mortality in pyruvate dehydrogenase deficiency: A case-based hypothesis.

Pyruvate dehydrogenase (PDH) deficiency is an inherited metabolic disorder caused by a defect in any subunit of the pyruvate dehydrogenase complex (PDHC), which has an essential role in glucose metabolism. The causes of disease progression in PDH deficiency are not fully understood yet. Based on repeated observations of a patient with PDH deficiency at our center, we hypothesized that stress-induced gluconeogenesis contributes to rapid exacerbation of the disease. This link has not been established previously.

Pyruvate dehydrogenase deficiency: morphological and metabolic effects, creation of animal model to search for curative treatment.

The main source of energy for brain and other organs is glucose. To obtain energy for all tissue, glucose has to come through glycolysis; then as pyruvate it is converted to acetyl-CoA by pyruvate dehydrogenase complex (PDC) and finally enters citric acid cycle. What happens when one of these stages become disturb? Mutation in genes encoding subunits of PDC leads to pyruvate dehydrogenase deficiency. Abnormalities in PDC activity result in severe metabolic and brain malformations. For better understanding the development and mechanism of pyruvate dehydrogenase deficiency the murine model of this disease has been created. Studies on a murine model showed similar malformation in brain structures as in the patients suffered from pyruvate dehydrogenase deficiency such as reduced neuronal density, heterotopias of grey matter, reduced size of corpus callosum and pyramids. There is still no effective cure for PDC-deficiency. Promising therapy seemed to be ketogenic diet, which substitutes glucose to ketone bodies as a source of energy. Studies have shown that ketogenic diet decreases lactic acidosis and inhibits brain malformations, but not the mortality in early childhood. The newest reports say that phenylbutyrate increases the level of PDC in the brain, because it reduces the level of inactive form of PDH. Experiments on human fibroblast and zebra fish PDC-deficiency model showed that phenylbutyrate is promising cure to PDC-deficiency. This review summarizes the most important findings on the metabolic and morphological effects of PDC-deficiency and research for treatment therapy.

Pyruvate Dehydrogenase Complex Deficiency: An Unusual Cause of Recurrent Lactic Acidosis in a Paediatric Critical Care Unit.

Pyruvate dehydrogenase complex deficiency (PDCD) is a rare neurodegenerative disorder associated with abnormal mitochondrial metabolism. Structural brain abnormalities are common in PDCD. A case of a patient with PDCD with an unusual presentation is described. A 20-month-old boy with hypotonia and developmental delay, presented with hypoxia and respiratory distress due to bronchiolitis. During hospitalisation, he was prescribed PediaSure® feeds. Two days after starting these feeds, he developed respiratory arrest requiring intubation. His blood gas before arrest revealed lactate of 8.9 mmol/L despite normal haemodynamics. After stabilisation and a period of compulsory fasting, subsequent feeding with PediaSure® resulted in the recurrence of lactic acidosis. A metabolic workup revealed an elevated serum pyruvate level. Brain MRI was normal. Skeletal muscle biopsy confirmed PDCD. The most common cause of PDCD is a mutation in the X-linked PDHA1 gene. The severity of PDCD can range from neonatal death to more delayed onset of symptoms as in our index case. Normal brain MRI is reported in only 2% of patients with PDCD. There is no effective treatment for PDCD. In patients with proximal muscle weakness and feeding intolerance with glucose-containing feeds, the presence of lactic acidosis should raise the suspicion of PDCD irrespective of the patient's age and normal MRI.

Food and Food Products on the Italian Market for Ketogenic Dietary Treatment of Neurological Diseases.

The ketogenic diet (KD) is the first line intervention for glucose transporter 1 deficiency syndrome and pyruvate dehydrogenase deficiency, and is recommended for refractory epilepsy. It is a normo-caloric, high-fat, adequate-protein, and low-carbohydrate diet aimed at switching the brain metabolism from glucose dependence to the utilization of ketone bodies. Several variants of KD are currently available. Depending on the variant, KDs require the almost total exclusion, or a limited consumption of carbohydrates. Thus, there is total avoidance, or a limited consumption of cereal-based foods, and a reduction in fruit and vegetable intake. KDs, especially the more restrictive variants, are characterized by low variability, palatability, and tolerability, as well as by side-effects, like gastrointestinal disorders, nephrolithiasis, growth retardation, hyperlipidemia, and mineral and vitamin deficiency. In recent years, in an effort to improve the quality of life of patients on KDs, food companies have started to develop, and commercialize, several food products specific for such patients. This review summarizes the foods themselves, including sweeteners, and food products currently available for the ketogenic dietary treatment of neurological diseases. It describes the nutritional characteristics and gives indications for the use of the different products, taking into account their metabolic and health effects.

Ketogenic Diets in the Treatment of Epilepsy.

BACKGROUND: Although a larger number of antiepileptic drugs became available in the last decades, epilepsy remains drug-resistant in approximately a third of patients. Ketogenic diet (KD), first proposed at the beginning of the last century, is complex and has anticonvulsant effects, yet not completely understood. Over the last decades, different types of ketogenic diets (KDs) have been developed, namely classical KD and modified Atkins diet (MAD). They offer an effective alternative for children and adults with drug-resistant epilepsies. METHODS: We review several papers on KDs as an adjunctive treatment of refractory epilepsy of children and adults, discussing its efficacy and adverse events. Because of the heterogenous, uncontrolled nature of the studies, we analyzed all studies individually, without a meta-analysis. RESULTS: KDs may be considered first choice treatment in some specific metabolic conditions, such as glucosetransporter type 1 and pyruvate dehydrogenase deficiencies, and mitochondrial complex I defects. Preliminary findings indicate that KDs may be specifically effective in some epileptic syndromes, such as West syndrome, severe myoclonic epilepsy of infancy, myoclonic-astatic epilepsy, febrile infection related epileptic syndrome, and drug-resistant idiopathic generalized epilepsies or refractory status epilepticus. Short term adverse events are usually mild in both children and adults, including gastrointestinal symptoms, hyperlipidemia, and hypercalciuria; potential long term adverse effects include nephrolitiasis, decreased bone density, and liver steatosis. Possible atherosclerotic effects remain a concern. Patients on KDs should be carefully monitored in specialized centers during initiation, maintenance and withdrawal periods, in order to minimize such adverse events, and to improve compliance. Although the majority of KD trials on children and adults with drug-resistant epilepsies are openlabel, uncontrolled studies based on small samples, an increasing number of randomized controlled trials have provided better quality evidence on its efficacy in recent years. CONCLUSION: There is a need for future randomized clinical trials aimed to confirm the efficacy of KDs in specific epileptic syndromes, and to provide further information about some practical unsolved problems, i.e. for how long KD treatment should be continued.

Recessive mutation in EXOSC3 associates with mitochondrial dysfunction and pontocerebellar hypoplasia.

Recessive mutations in EXOSC3, encoding a subunit of the human RNA exosome complex, cause pontocerebellar hypoplasia type 1b (PCH1B). We report a boy with severe muscular hypotonia, psychomotor retardation, progressive microcephaly, and cerebellar atrophy. Biochemical abnormalities comprised mitochondrial complex I and pyruvate dehydrogenase complex (PDHc) deficiency. Whole exome sequencing uncovered a known EXOSC3 mutation p.(D132A) as the underlying cause. In patient fibroblasts, a large portion of the EXOSC3 protein was trapped in the cytosol. MtDNA copy numbers in muscle were reduced to 35%, but mutations in the mtDNA and in nuclear mitochondrial genes were ruled out. RNA-Seq of patient muscle showed highly increased mRNA copy numbers, especially for genes encoding structural subunits of OXPHOS complexes I, III, and IV, possibly due to reduced degradation by a dysfunctional exosome complex. This is the first case of mitochondrial dysfunction associated with an EXOSC3 mutation, which expands the phenotypic spectrum of PCH1B. We discuss the links between exosome and mitochondrial dysfunction.

Phenotypic and Neuropathological Characterization of Fetal Pyruvate Dehydrogenase Deficiency.

To distinguish pyruvate dehydrogenase deficiency (PDH) from other antenatal neurometabolic disorders thereby improving prenatal diagnosis, we describe imaging findings, clinical phenotype, and brain lesions in fetuses from 3 families with molecular characterization of this condition. Neuropathological analysis was performed in 4 autopsy cases from 3 unrelated families with subsequent biochemical and molecular confirmation of PDH complex deficiency. In 2 families there were mutations in the PDHA1 gene; in the third family there was a mutation in the PDHB gene. All fetuses displayed characteristic craniofacial dysmorphism of varying severity, absence of visceral lesions, and associated encephaloclastic and developmental supra- and infratentorial lesions. Neurodevelopmental abnormalities included microcephaly, migration abnormalities (pachygyria, polymicrogyria, periventricular nodular heterotopias), and cerebellar and brainstem hypoplasia with hypoplastic dentate nuclei and pyramidal tracts. Associated clastic lesions included asymmetric leukomalacia, reactive gliosis, large pseudocysts of germinolysis, and basal ganglia calcifications. The diagnosis of PDH deficiency should be suspected antenatally with the presence of clastic and neurodevelopmental lesions and a relatively characteristic craniofacial dysmorphism. Postmortem examination is essential for excluding other closely related entities, thereby allowing for biochemical and molecular confirmation.

Pyruvate dehydrogenase deficiency presenting as isolated paroxysmal exercise induced dystonia successfully reversed with thiamine supplementation. Case report and mini-review.

BACKGROUND: Pyruvate dehydrogenase (PDH) deficiency is a disorder of energy metabolism with variable clinical presentations, ranging from severe infantile lactic acidosis to milder chronic neurological disorders. The spectrum of clinical manifestations is continuously expanding. METHODS AND RESULTS: We report on a 19-year-old intelligent female with PDH deficiency caused by a Leu216Ser mutation in PDHA1. She presented with recurrent hemidystonic attacks, triggered by prolonged walking or running, as the unique clinical manifestation that manifested since childhood. Laboratory workup and neuroimages were initially normal but bilateral globus pallidum involvement appeared later on brain MRI. Dystonia completely remitted after high doses of thiamine, remaining free of symptoms after 3 years of follow up. We reviewed the literature for similar observations. CONCLUSIONS: Dystonia precipitated by exercise may be the only symptom of a PDH deficiency, and the hallmark of the disease as high serum lactate or bilateral striatal necrosis at neuroimaging may be absent. A high index of suspicion and follow up is necessary for diagnosis. The clinical presentation of this patient meets the criteria for a Paroxysmal Exercise induced Dystonia, leading us to add this entity as another potential etiology for this type of paroxysmal dyskinesia, which is besides a treatable condition that responds to thiamine supplementation.

Leukoencephalopathy with cysts and hyperglycinemia may result from NFU1 deficiency.

Lipoic acid metabolism defects are new metabolic disorders that cause neurological, cardiomuscular or pulmonary impairment. We report on a patient that presented with progressive neurological regression suggestive of an energetic disease, involving leukoencephalopathy with cysts. Elevated levels of glycine in plasma, urine and CSF associated with intermittent increases of lactate were consistent with a defect in lipoic acid metabolism. Support for the diagnosis was provided by pyruvate dehydrogenase deficiency and multiple mitochondrial respiratory chain deficiency in skin fibroblasts, as well as no lipoylated protein by western blot. Two mutations in the NFU1 gene confirmed the diagnosis. The p.Gly208Cys mutation has previously been reported suggesting a founder effect in Europe.