Pubertal origin of growth retardation in inborn errors of protein metabolism: A longitudinal cohort study.

OBJECTIVES: Inherited amino-acid metabolism disorders (IAAMDs) require lifelong protein-restricted diet. We aimed to investigate: 1/ whether IAAMDs was associated with growth, pubertal, bone mineral apparent density (BMAD) or body composition impairments; 2/ associations linking height, amino-acid mixture (AAM), plasma amino-acids and IGF1 concentrations. DESIGN: Retrospective longitudinal study of 213 patients with neonatal-onset urea cycle disorders (UCD,n = 77), organic aciduria (OA,n = 89), maple syrup urine disease (MSUD,n = 34), or tyrosinaemia type 1 (n = 13). METHODS: We collected growth parameters, pubertal status, BMAD, body composition, protein-intake, and IGF1 throughout growth. RESULTS: Overall final height (n = 69) was below target height (TH): -0.9(1.4) vs. -0.1(0.9) SD, p < 0.001. Final height was ≤ TH-2SD in 12 (21%) patients. Height ≤ - 2SD was more frequent during puberty than during early-infancy and pre-puberty: 23.5% vs. 6.9%, p = 0.002; and vs. 10.7%, p < 0.001. Pubertal delay was frequent (26.7%). Height (SD) was positively associated with isoleucine concentration: ß, 0.008; 95%CI, 0.003 to 0.012; p = 0.001. In the pubertal subgroup, height (SD) was lower in patients with vs. without AAM supplementation: -1.22 (1.40) vs. -0.63 (1.46) (p = 0.02). In OA, height and median (IQR) isoleucine and valine concentrations(µmol/L) during puberty were lower in patients with vs. without AAM supplementation: -1.75 (1.30) vs. -0.33 (1.55) SD, p < 0.001; and 40 (23) vs. 60 (25) (p = 0.02) and 138 (92) vs. 191 (63) (p = 0.01), respectively. No correlation was found with IGF1. Lean-mass index was lower than fat-mass index: -2.03 (1.15) vs. -0.44 (0.89), p < 0.001. CONCLUSIONS: In IAAMDs, growth retardation worsened during puberty which was delayed in all disease subgroups. Height seems linked to the disease, AAM composition and lower isoleucine concentration, independently of the GH-IGF1 pathway. We recommend close monitoring of diet during puberty.

Successful treatment of severe MSUD in Bckdhb-/- mice with neonatal AAV gene therapy.

Maple syrup urine disease (MSUD) is rare autosomal recessive metabolic disorder caused by the dysfunction of the mitochondrial branched-chain 2-ketoacid dehydrogenase (BCKD) enzyme complex leading to massive accumulation of branched-chain amino acids and 2-keto acids. MSUD management, based on a life-long strict protein restriction with nontoxic amino acids oral supplementation represents an unmet need as it is associated with a poor quality of life, and does not fully protect from acute life-threatening decompensations or long-term neuropsychiatric complications. Orthotopic liver transplantation is a beneficial therapeutic option, which shows that restoration of only a fraction of whole-body BCKD enzyme activity is therapeutic. MSUD is thus an ideal target for gene therapy. We and others have tested AAV gene therapy in mice for two of the three genes involved in MSUD, BCKDHA and DBT. In this study, we developed a similar approach for the third MSUD gene, BCKDHB. We performed the first characterization of a Bckdhb-/- mouse model, which recapitulates the severe human phenotype of MSUD with early-neonatal symptoms leading to death during the first week of life with massive accumulation of MSUD biomarkers. Based on our previous experience in Bckdha-/- mice, we designed a transgene carrying the human BCKDHB gene under the control of a ubiquitous EF1α promoter, encapsidated in an AAV8 capsid. Injection in neonatal Bckdhb-/- mice at 1014 vg/kg achieved long-term rescue of the severe MSUD phenotype of Bckdhb-/- mice. These data further validate the efficacy of gene therapy for MSUD opening perspectives towards clinical translation.

Methionine supplementation for multi-organ dysfunction in MetRS-related pulmonary alveolar proteinosis.

INTRODUCTION: Pulmonary alveolar proteinosis related to mutations in the methionine tRNA synthetase (MARS1) gene is a severe, early-onset disease that results in death before the age of 2 years in one-third of patients. It is associated with a liver disease, growth failure and systemic inflammation. As methionine supplementation in yeast models restored normal enzymatic activity of the synthetase, we studied the tolerance, safety and efficacy of daily oral methionine supplementation in patients with severe and early disease. METHODS: Four patients received methionine supplementation and were followed for respiratory, hepatic, growth and inflammation-related outcomes. Their course was compared to those of historical controls. Reactive oxygen species production by patient monocytes before and after methionine supplementation was also studied. RESULTS: Methionine supplementation was associated with respiratory improvement, clearance of the extracellular lipoproteinaceous material and discontinuation of whole-lung lavage in all patients. The three patients who required oxygen or noninvasive ventilation could be weaned off within 60 days. In addition, liver dysfunction, inflammation and growth delay improved or resolved. At a cellular level, methionine supplementation normalised the production of reactive oxygen species by peripheral monocytes. CONCLUSION: Methionine supplementation was associated with important improvements in children with pulmonary alveolar proteinosis related to mutations in the MARS1 gene. This study paves the way for similar strategies for other tRNA synthetase deficiencies.

Impaired Transferrin Receptor Palmitoylation and Recycling in Neurodegeneration with Brain Iron Accumulation.

Neurodegeneration with brain iron accumulation (NBIA) is a genetically heterogeneous condition characterized by progressive dystonia with iron accumulation in the basal ganglia. How NBIA-associated mutations trigger iron overload remains poorly understood. After studying fibroblast cell lines from subjects carrying both known and unreported biallelic mutations in CRAT and REPS1, we ascribe iron overload to the abnormal recycling of transferrin receptor (TfR1) and the reduction of TfR1 palmitoylation in NBIA. Moreover, we describe palmitoylation as a hitherto unreported level of post-translational TfR1 regulation. A widely used antimalarial agent, artesunate, rescued abnormal TfR1 palmitoylation in cultured fibroblasts of NBIA subjects. These observations suggest therapeutic strategies aimed at targeting impaired TfR1 recycling and palmitoylation in NBIA.

OTC deficiency in females: Phenotype-genotype correlation based on a 130-family cohort.

OTC deficiency, an inherited urea cycle disorder, is caused by mutations in the X-linked OTC gene. Phenotype-genotype correlations are well understood in males but still poorly known in females. Taking advantage of a cohort of 130 families (289 females), we assessed the relative contribution of OTC enzyme activity, X chromosome inactivation, and OTC gene sequencing to genetic counseling in heterozygous females. Twenty two percent of the heterozygous females were clinically affected, with episodic (11%), chronic (7.5%), or neonatal forms of the disease (3.5%). Overall mortality rate was 4%. OTC activity, ranging from 0% to 60%, did not correlate with phenotype at the individual level. Analysis of multiple samples from 4 mutant livers showed intra-hepatic variability of OTC activity and X inactivation profile (range of variability: 30% and 20%, respectively) without correlation between both parameters for 3 of the 4 livers. Ninety disease-causing variants were found, 27 of which were novel. Mutations were classified as "mild" or "severe," based on male phenotypes and/or in silico prediction. In our cohort, a serious disease occurred in 32% of females with a severe mutation, compared to 4% in females with a mild mutation (odds ratio = 1.365; P = 1.6e-06). These data should help prenatal diagnosis for heterozygous females and genetic counseling after fortuitous findings of OTC variants in pangenomic sequencing.

Clinical and biological characterization of 20 patients with TANGO2 deficiency indicates novel triggers of metabolic crises and no primary energetic defect.

TANGO2 disease is a severe inherited disorder associating multiple symptoms such as metabolic crises, encephalopathy, cardiac arrhythmias, and hypothyroidism. The mechanism of action of TANGO2 is currently unknown. Here, we describe a cohort of 20 French patients bearing mutations in the TANGO2 gene. We found that the main clinical presentation was the association of neurodevelopmental delay (n = 17), acute metabolic crises (n = 17) and hypothyroidism (n = 12), with a large intrafamilial clinical variability. Metabolic crises included rhabdomyolysis (15/17), neurological symptoms (14/17), and cardiac features (12/17; long QT (n = 10), Brugada pattern (n = 2), cardiac arrhythmia (n = 6)) that required intensive care. We show previously uncharacterized triggers of metabolic crises in TANGO2 patients, such as some anesthetics and possibly l-carnitine. Unexpectedly, plasma acylcarnitines, plasma FGF-21, muscle histology, and mitochondrial spectrometry were mostly normal. Moreover, in patients' primary myoblasts, palmitate and glutamine oxidation rates, and the mitochondrial network were also normal. Finally, we found variable mitochondrial respiration and defective clearance of oxidized DNA upon cycles of starvation and refeeding. We conclude that TANGO2 disease is a life-threatening disease that needs specific cardiac management and anesthesia protocol. Mechanistically, TANGO2 disease is unlikely to originate from a primary mitochondrial defect. Rather, we suggest that mitochondrial defects are secondary to strong extrinsic triggers in TANGO2 deficient patients.

Biallelic Mutations in LIPT2 Cause a Mitochondrial Lipoylation Defect Associated with Severe Neonatal Encephalopathy.

Lipoate serves as a cofactor for the glycine cleavage system (GCS) and four 2-oxoacid dehydrogenases functioning in energy metabolism (α-oxoglutarate dehydrogenase [α-KGDHc] and pyruvate dehydrogenase [PDHc]), or amino acid metabolism (branched-chain oxoacid dehydrogenase, 2-oxoadipate dehydrogenase). Mitochondrial lipoate synthesis involves three enzymatic steps catalyzed sequentially by lipoyl(octanoyl) transferase 2 (LIPT2), lipoic acid synthetase (LIAS), and lipoyltransferase 1 (LIPT1). Mutations in LIAS have been associated with nonketotic hyperglycinemia-like early-onset convulsions and encephalopathy combined with a defect in mitochondrial energy metabolism. LIPT1 deficiency spares GCS deficiency and has been associated with a biochemical signature of combined 2-oxoacid dehydrogenase deficiency leading to early death or Leigh-like encephalopathy. We report on the identification of biallelic LIPT2 mutations in three affected individuals from two families with severe neonatal encephalopathy. Brain MRI showed major cortical atrophy with white matter abnormalities and cysts. Plasma glycine was mildly increased. Affected individuals' fibroblasts showed reduced oxygen consumption rates, PDHc, α-KGDHc activities, leucine catabolic flux, and decreased protein lipoylation. A normalization of lipoylation was observed after expression of wild-type LIPT2, arguing for LIPT2 requirement in intramitochondrial lipoate synthesis. Lipoic acid supplementation did not improve clinical condition nor activities of PDHc, α-KGDHc, or leucine metabolism in fibroblasts and was ineffective in yeast deleted for the orthologous LIP2.

Neonatal factors related to survival and intellectual and developmental outcome of patients with early-onset urea cycle disorders.

PURPOSE: We aimed to identify prognostic factors for survival and long-term intellectual and developmental outcome in neonatal patients with early-onset urea cycle disorders (UCD) experiencing hyperammonaemic coma. METHODS: We retrospectively analysed ammonia (NH3) and glutamine levels, electroencephalogram and brain images obtained during neonatal coma of UCD patients born between 1995 and 2011 and managed at a single centre and correlated them to survival and intellectual and developmental outcome. RESULTS: We included 38 neonates suffering from deficiencies of argininosuccinate synthetase (ASSD, N = 12), ornithine transcarbamylase (OTCD, N = 10), carbamoylphosphate synthetase 1 (CPSD, N = 7), argininosuccinate lyase (ASLD, N = 7), N-acetylglutamate synthase (NAGS, N = 1) or arginase (ARGD, N = 1). Symptoms occurred earlier in mitochondrial than in cytosolic UCD. Sixty-eight percent of patients survived, with a mean (standard deviation-SD) follow-up of 10.4 (5.3) years. Mortality was mostly observed in OTCD (N = 7/10) and CPSD (N = 4/7) patients. Plasma NH3 level during the neonatal period, expressed as area under the curve, but not glutamine level was associated with mortality (p = .044 and p = .610). 62.1% of the patients had normal intellectual and developmental outcome. Intellectual and developmental outcome tended to correlate with UCD subtype (p = .052). No difference in plasma NH3 or glutamine level during the neonatal period among developmental outcomes was identified. EEG severity was linked to UCD subtypes (p = .004), ammonia levels (p = .037), duration of coma (p = .043), and mortality during the neonatal period (p = .020). Status epilepticus was recorded in 6 patients, 3 of whom died neonatally, 1 developed a severe intellectual disability while the 2 last patients had a normal development. CONCLUSION: UCD subtypes differed by survival rate, intellectual and developmental outcome and EEG features in the neonatal period. Hyperammonaemia expressed as area under the curve was associated with survival but not with intellectual and developmental outcome whereas glutamine was not associated with one of these outcomes. Prognostic value of video-EEG monitoring and the association between status epilepticus and mortality should be assessed in neonatal hyperammonaemic coma in further studies.

Long-term outcome of methylmalonic aciduria after kidney, liver, or combined liver-kidney transplantation: The French experience.

Organ transplantation is discussed in methylmalonic aciduria (MMA) for renal failure, and poor quality of life and neurological outcome. We retrospectively evaluated 23 French MMA patients after kidney (KT), liver-kidney (LKT), and liver transplantation (LT). Two patients died, one after LKT, one of hepatoblastoma after KT. One graft was lost early after KT. Of 18 evaluable patients, 12 previously on dialysis, 8 underwent KT (mean 12.5 years), 8 LKT (mean 7 years), and 2 LT (7 and 2.5 years). At a median follow-up of 7.3 (KT), 2.3 (LKT), and 1.0 years (LT), no metabolic decompensation occurred except in 1 KT. Plasma and urine MMA levels dramatically decreased, more after LKT. Protein intake was increased more significantly after LKT than KT. Enteral nutrition was stopped in 7/8 LKT, 1/8 KT. Early complications were frequent after LKT. Neurological disorders occurred in four LKT, reversible in one. Five years after KT, four patients had renal failure. The metabolic outcomes were much better after LKT than KT. LKT in MMA is difficult but improves the quality of life. KT will be rarely indicated. We need more long-term data to indicate early LT, in the hope to delay renal failure and prevent neurodevelopmental complications.

5-Fluorouracil rechallenge after 5-fluorouracil-induced hyperammonemic encephalopathy.

For several decades, 5-Fluorouracil (5-FU) has been the backbone of many chemotherapy regimens for various tumor types. Its most common side effects are gastrointestinal disorders, mucositis, myelosuppression, hand-foot syndrome, and rarely cardiac toxicity. More rarely, 5-FU infusion can induce hyperammonemic encephalopathy. 5-FU toxicities can be worsened by complete or partial genetic and/or phenotypic dihydropyrimidine dehydrogenase deficiency. Here, we report the case of a patient who initially developed a 5-FU-induced hyperammonemic encephalopathy after receiving FOLFIRINOX (oxaliplatin, irinotecan, folinic acid, and 5-FU) chemotherapy with bevacizumab to treat a metastatic gastrointestinal cancer of unknown primary. Thereafter, the patient was rechallenged successfully by the same chemotherapy regimen (FOLFIRINOX) for more than 6 months with a protocol consisting in a free protein diet, and administration of ammonium chelators, and Krebs and urea cycle intermediates, to prevent further hyperammonemia. We also present a review of the literature on 5-FU rechallenge after 5-FU-induced hyperammonemic encephalopathy.

Autism spectrum disorders in propionic acidemia patients.

Propionic acidemia is the result of a deficiency in propionyl-CoA carboxylase activity. Chronic neurologic and cognitive complications frequently occur, but the psychiatric evolution of the disorder is not well documented. We conducted a pedopsychiatric evaluation of 19 children, adolescents and young adults, aged between 2 and 25 years, using ADI-R, CARS-T, as well as ADOS when autism spectrum disorder was suspected. Previous psychometric examinations were also taken into consideration. Thirteen patients had an IQ < 80. Two patients presented with autism and two additional patients with other autism spectrum disorders. Five patients did not fulfill diagnostic criteria for autism spectrum disorder but showed difficulties indicative of a broader autism phenotype (BAP). Four other patients had severe anxiety manifestations related to their disease. Two patients presented with acute psychotic episodes. The number of decompensations in the first 3 years of life was lower in patients with autism spectrum disorder or related symptoms. These patients were also older when they were assessed (median age of 15 years old versus 11 years old). There was no significant correlation between 3-hydroxypropionate levels during the first 6 years of life and autism spectrum disorder diagnosis. In conclusion, autism spectrum disorder is frequent in patients with propionic acidemia. These patients should undergo in-depth psychiatric evaluation and be screened for autism spectrum disorder. Further studies are needed to understand the underlying mechanisms.

Peak hyperammonemia and atypical acute liver failure: The eruption of an urea cycle disorder during hyperemesis gravidarum.

Inborn urea cycle disorders are under-recognised metabolic causes of hyperammonemia in adults. A 28-year-old primigravida, seven weeks pregnant, affected by hyperemesis gravidarum developed acute liver injury (ALI) and then acute liver failure (ALF) in less than 48 h. Because the patient developed atypical features, especially mildly elevated aminotransferases contrasting with very high blood ammonia levels (281 µmol/L), concomitant with normal serum creatinine, an inborn error of metabolism was suspected. We performed emergency metabolic analyses, stopped all protein intake and started with intravenous (i.v.) high caloric intake, nitrogen scavenger drugs and haemodialysis. The neurological and hepatic status of the patient quickly improved together with normalisation of her ammonemia levels. High plasma glutamine and urinary orotic acid, alongside low plasma arginine, citrulline and ornithine were suggestive of an ornithine transcarbamylase deficiency, later confirmed by molecular analyses. Foetal sex was female, as determined by foetal DNA analysis in maternal blood, and foetal development was unremarkable throughout the pregnancy. Delivery was induced at 39 weeks with a close monitoring of ammonemia levels and i.v. perfusion of carbohydrates and lipids during labour and immediately post-partum to avoid hypercatabolism. Delivery was uneventful and the patient delivered a healthy female baby. Urea cycle disorders should be contemplated in non-jaundiced patients with ALI or ALF, severe hyperammonemia and normal serum creatinine regardless of serum aminotransferase levels. The prompt recognition of this rare condition and the rapid initiation of adequate metabolic therapy are mandatory to prevent irreversible neurological sequelae and to avoid liver transplantation.

A driver role for GABA metabolism in controlling stem and proliferative cell state through GHB production in glioma.

Cell populations with differing proliferative, stem-like and tumorigenic states co-exist in most tumors and especially malignant gliomas. Whether metabolic variations can drive this heterogeneity by controlling dynamic changes in cell states is unknown. Metabolite profiling of human adult glioblastoma stem-like cells upon loss of their tumorigenicity revealed a switch in the catabolism of the GABA neurotransmitter toward enhanced production and secretion of its by-product GHB (4-hydroxybutyrate). This switch was driven by succinic semialdehyde dehydrogenase (SSADH) downregulation. Enhancing GHB levels via SSADH downregulation or GHB supplementation triggered cell conversion into a less aggressive phenotypic state. GHB affected adult glioblastoma cells with varying molecular profiles, along with cells from pediatric pontine gliomas. In all cell types, GHB acted by inhibiting α-ketoglutarate-dependent Ten-eleven Translocations (TET) activity, resulting in decreased levels of the 5-hydroxymethylcytosine epigenetic mark. In patients, low SSADH expression was correlated with high GHB/α-ketoglutarate ratios, and distinguished weakly proliferative/differentiated glioblastoma territories from proliferative/non-differentiated territories. Our findings support an active participation of metabolic variations in the genesis of tumor heterogeneity.

Long-term metabolic follow-up and clinical outcome of 35 patients with maple syrup urine disease.

BACKGROUND: Maple syrup urine disease (MSUD) is a rare disease that requires a protein-restricted diet for successful management. Little is known, however, about the psychosocial outcome of MSUD patients. This study investigates the relationship between metabolic and clinical parameters and psychosocial outcomes in a cohort of patients with neonatal-onset MSUD. METHODS: Data on academic achievement, psychological care, family involvement, and biochemical parameters were collected from the medical records of neonatal MSUD patients treated at Necker Hospital (Paris) between 1964 and 2013. RESULTS: Thirty-five MSUD patients with a mean age of 16.3 (2.1-49.0) years participated. Metabolic decompensations (plasma leucine >380 µmol/L) were more frequent during the first year of life and after 15 years, mainly due to infection and dietary noncompliance, respectively. Leucine levels increased significantly in adulthood: 61.5% of adults were independent and achieved adequate social and professional integration; 56% needed occasional or sustained psychological or psychiatric care (8/19, with externalizing, mood, emotional, and anxiety disorders being the most common). Patients needing psychiatric care were significantly older [mean and standard deviation (SD) 22.6 (7.7) years] than patients needing only psychological follow-up [mean (SD) 14.3 (8.9) years]. Patients with psychological follow-up experienced the highest lifetime number of decompensations; 45% of families had difficulty coping with the chronic disease. Parental involvement was negatively associated with the number of lifetime decompensations. CONCLUSION: Adults had increased levels of plasma leucine, consistent with greater chronic toxicity. Psychological care was associated with age and number of decompensations. In addition, parental involvement appeared to be crucial in the management of MSUD patients.

Neurocognitive profiles in MSUD school-age patients.

Maple syrup urine disease (MSUD), an inborn error of amino acids catabolism is characterized by accumulation of branched chain amino acids (BCAAs) leucine, isoleucine, valine and their corresponding alpha-ketoacids. Impact on the cognitive development has been reported historically, with developmental delays of varying degree. Currently, earlier diagnosis and improved management allow a better neurodevelopment, without requirement of special education. However, specific impairments can be observed, and so far, results of detailed neurocognitive assessments are not available. The aim of this study was to analyse neurocognitive profiles of French MSUD patients. This was a multicentre retrospective study on MSUD patients who underwent neurocognitive evaluation at primary school age. Twenty-one patients with classical neonatal onset MSUD were included. The patients' mean age at the time of evaluation was 8.7 years. The mean intellectual quotient (IQ) score was in the normal range (95.1 ± 12.6). In a subset of eight patients, a consistent developmental pattern of higher verbal than performance IQ was observed (mean of the difference 25.7 ± 8.7, p < 0.0001). No correlation could be established between this pattern and long-term metabolic balance (BCAA blood levels), or severity of acute metabolic imbalances, or leucine blood levels at diagnosis and time to toxin removal procedure. These data show that some MSUD patients may exhibit an abnormal neurocognitive profile with higher verbal than performance abilities. This might suggest an executive dysfunction disorder that would need to be further investigated by specialized testing. This pattern is important to detect in MSUD, as appropriate neuropsychological treatment strategies should be proposed.

A thermolabile aldolase A mutant causes fever-induced recurrent rhabdomyolysis without hemolytic anemia.

Aldolase A deficiency has been reported as a rare cause of hemolytic anemia occasionally associated with myopathy. We identified a deleterious homozygous mutation in the ALDOA gene in 3 siblings with episodic rhabdomyolysis without hemolytic anemia. Myoglobinuria was always triggered by febrile illnesses. We show that the underlying mechanism involves an exacerbation of aldolase A deficiency at high temperatures that affected myoblasts but not erythrocytes. The aldolase A deficiency was rescued by arginine supplementation in vitro but not by glycerol, betaine or benzylhydantoin, three other known chaperones, suggesting that arginine-mediated rescue operated by a mechanism other than protein chaperoning. Lipid droplets accumulated in patient myoblasts relative to control and this was increased by cytokines, and reduced by dexamethasone. Our results expand the clinical spectrum of aldolase A deficiency to isolated temperature-dependent rhabdomyolysis, and suggest that thermolability may be tissue specific. We also propose a treatment for this severe disease.

Controversies and research agenda in nephropathic cystinosis: conclusions from a "Kidney Disease: Improving Global Outcomes" (KDIGO) Controversies Conference.

Nephropathic cystinosis is an autosomal recessive metabolic, lifelong disease characterized by lysosomal cystine accumulation throughout the body that commonly presents in infancy with a renal Fanconi syndrome and, if untreated, leads to end-stage kidney disease (ESKD) in the later childhood years. The molecular basis is due to mutations in CTNS, the gene encoding for the lysosomal cystine-proton cotransporter, cystinosin. During adolescence and adulthood, extrarenal manifestations of cystinosis develop and require multidisciplinary care. Despite substantial improvement in prognosis due to cystine-depleting therapy with cysteamine, no cure of the disease is currently available. Kidney Disease: Improving Global Outcomes (KDIGO) convened a Controversies Conference on cystinosis to review the state-of-the-art knowledge and to address areas of controversies in pathophysiology, diagnostics, monitoring, and treatment in different age groups. More importantly, promising areas of investigation that may lead to optimal outcomes for patients afflicted with this lifelong, systemic disease were discussed with a research agenda proposed for the future.

CIC inactivating mutations identify aggressive subset of 1p19q codeleted gliomas.

OBJECTIVE: CIC gene is frequently mutated in oligodendroglial tumors with 1p19q codeletion. However, clinical and biological impact remain poorly understood. METHODS: We sequenced the CIC gene on 127 oligodendroglial tumors (109 with the 1p19q codeletion) and analyzed patients' outcome. We compared magnetic resonance imaging, transcriptomic profile, and CIC protein expression of CIC wild-type (WT) and mutant gliomas. We compared the level of expression of CIC target genes on Hs683-IDH1(R132H) cells transfected with lentivirus encoding mutant and WT CIC. RESULTS: We found 63 mutations affecting 60 of 127 patients, virtually all 1p19q codeleted and IDH mutated (59 of 60). In the 1p19q codeleted gliomas, CIC mutations were associated with a poorer outcome by uni- (p = 0.001) and multivariate analysis (p < 0.016). CIC mutation prognostic impact was validated on the TCGA cohort. CIC mutant grade II codeleted gliomas spontaneously grew faster than WTs. Transcriptomic analysis revealed an enrichment of proliferative pathways and oligodendrocyte precursor cell gene expression profile in CIC mutant gliomas, with upregulation of normally CIC repressed genes ETV1, ETV4, ETV5, and CCND1. Various missense mutations resulted in CIC protein expression loss. Moreover, a truncating CIC mutation resulted in a defect of nuclear targeting of CIC protein to the nucleus in a human glioma cell line expressing IDH1(R132H) and overexpression of CCND1 and other new target genes of CIC, such as DUSP4 and SPRED1. INTERPRETATION: CIC mutations result in protein inactivation with upregulation of CIC target genes, activation of proliferative pathways, inhibition of differentiation, and poorer outcome in patients with a 1p19q codeleted glioma.

Triheptanoin dramatically reduces paroxysmal motor disorder in patients with GLUT1 deficiency.

OBJECTIVE: On the basis of our previous work with triheptanoin, which provides key substrates to the Krebs cycle in the brain, we wished to assess its therapeutic effect in patients with glucose transporter type 1 deficiency syndrome (GLUT1-DS) who objected to or did not tolerate ketogenic diets. METHODS: We performed an open-label pilot study with three phases of 2 months each (baseline, treatment and withdrawal) in eight patients with GLUT1-DS (7-47 years old) with non-epileptic paroxysmal manifestations. We used a comprehensive patient diary to record motor and non-motor paroxysmal events. Functional (31)P-NMR spectroscopy was performed to quantify phosphocreatine (PCr) and inorganic phosphate (Pi) within the occipital cortex during (activation) and after (recovery) a visual stimulus. RESULTS: Patients with GLUT1-DS experienced a mean of 30.8 (± 27.7) paroxysmal manifestations (52% motor events) at baseline that dropped to 2.8 (± 2.9, 76% motor events) during the treatment phase (p = 0.028). After withdrawal, paroxysmal manifestations recurred with a mean of 24.2 (± 21.9, 52% motor events; p = 0.043). Furthermore, brain energy metabolism normalised with triheptanoin, that is, increased Pi/PCr ratio during brain activation compared to the recovery phase (p = 0.021), and deteriorated when triheptanoin was withdrawn. CONCLUSIONS: Treatment with triheptanoin resulted in a 90% clinical improvement in non-epileptic paroxysmal manifestations and a normalised brain bioenergetics profile in patients with GLUT1-DS. TRIAL REGISTRATION NUMBER: NCT02014883.

Alteration of ornithine metabolism leads to dominant and recessive hereditary spastic paraplegia.

Hereditary spastic paraplegias are heterogeneous neurological disorders characterized by a pyramidal syndrome with symptoms predominantly affecting the lower limbs. Some limited pyramidal involvement also occurs in patients with an autosomal recessive neurocutaneous syndrome due to ALDH18A1 mutations. ALDH18A1 encodes delta-1-pyrroline-5-carboxylate synthase (P5CS), an enzyme that catalyses the first and common step of proline and ornithine biosynthesis from glutamate. Through exome sequencing and candidate gene screening, we report two families with autosomal recessive transmission of ALDH18A1 mutations, and predominant complex hereditary spastic paraplegia with marked cognitive impairment, without any cutaneous abnormality. More interestingly, we also identified monoallelic ALDH18A1 mutations segregating in three independent families with autosomal dominant pure or complex hereditary spastic paraplegia, as well as in two sporadic patients. Low levels of plasma ornithine, citrulline, arginine and proline in four individuals from two families suggested P5CS deficiency. Glutamine loading tests in two fibroblast cultures from two related affected subjects confirmed a metabolic block at the level of P5CS in vivo. Besides expanding the clinical spectrum of ALDH18A1-related pathology, we describe mutations segregating in an autosomal dominant pattern. The latter are associated with a potential trait biomarker; we therefore suggest including amino acid chromatography in the clinico-genetic work-up of hereditary spastic paraplegia, particularly in dominant cases, as the associated phenotype is not distinct from other causative genes.