Implication of folate deficiency in CYP2U1 loss of function.

Hereditary spastic paraplegias are heterogeneous neurodegenerative disorders. Understanding of their pathogenic mechanisms remains sparse, and therapeutic options are lacking. We characterized a mouse model lacking the Cyp2u1 gene, loss of which is known to be involved in a complex form of these diseases in humans. We showed that this model partially recapitulated the clinical and biochemical phenotypes of patients. Using electron microscopy, lipidomic, and proteomic studies, we identified vitamin B2 as a substrate of the CYP2U1 enzyme, as well as coenzyme Q, neopterin, and IFN-α levels as putative biomarkers in mice and fluids obtained from the largest series of CYP2U1-mutated patients reported so far. We also confirmed brain calcifications as a potential biomarker in patients. Our results suggest that CYP2U1 deficiency disrupts mitochondrial function and impacts proper neurodevelopment, which could be prevented by folate supplementation in our mouse model, followed by a neurodegenerative process altering multiple neuronal and extraneuronal tissues.

Clinical outcomes in a series of 18 patients with long chain fatty acids oxidation disorders treated with triheptanoin for a median duration of 22 months.

INTRODUCTION: Triheptanoin provides long-chain fatty acid oxidation disorder (LC-FAOD) patients with an alternative to medium-even-chain triglycerides therapy. MATERIAL-METHODS: Retrospective analysis of 18 French LC-FAOD patients benefiting from early access to triheptanoin treatment. RESULTS: Eight female and 10 male patients with LC-FAOD (VLCAD, LCHAD, CACT, CPTII and MTP) were treated with triheptanoin for a median duration of 22 months (range: 9-228 months). At last consultation, triheptanoin accounted for 15-35% of their daily caloric intake. In the year following the introduction of triheptanoin, patients reported a reduction of intermittent snacking and nocturnal meals. Three patients, including 1 adult, became free of severe hypoglycaemic events. Ten of 12 paediatric patients and 4 of 6 adult patients reported reduced fatigue with reductions in the number and severity of episodes of myalgia. Of 6 patients, including 1 adult, that had required the use of a wheelchair in the year prior to triheptanoin, all but one no longer required its use. The number of emergency hospitalizations decreased, and none were recorded for paediatric patients during these 12 months. Cumulative annual days of emergency care in the home were reduced from 286 to 51 days in the year before and after initiation, respectively, and 13 patients required no such interventions. Adverse events were limited to digestive issues that dissipated over time. CONCLUSIONS: Our case-series suggests that long-term treatment of LC-FAOD paediatric and adult patients with triheptanoin is safe and leads to marked improvement of symptoms and an improved quality of life.

A randomized, controlled, double-blind, crossover trial of triheptanoin in alternating hemiplegia of childhood.

BACKGROUND: Based on the hypothesis of a brain energy deficit, we investigated the safety and efficacy of triheptanoin on paroxysmal episodes in patients with alternating hemiplegia of childhood due to ATP1A3 mutations. METHODS: We conducted a randomized, double-blind, placebo-controlled crossover study of triheptanoin, at a target dose corresponding to 30% of daily calorie intake, in ten patients with alternating hemiplegia of childhood due to ATP1A3 mutations. Each treatment period consisted of a 12-week fixed-dose phase, separated by a 4-week washout period. The primary outcome was the total number of paroxysmal events. Secondary outcomes included the number of paroxysmal motor-epileptic events; a composite score taking into account the number, severity and duration of paroxysmal events; interictal neurological manifestations; the clinical global impression-improvement scale (CGI-I); and safety parameters. The paired non-parametric Wilcoxon test was used to analyze treatment effects. RESULTS: In an intention-to-treat analysis, triheptanoin failed to reduce the total number of paroxysmal events (p = 0.646), including motor-epileptic events (p = 0.585), or the composite score (p = 0.059). CGI-I score did not differ between triheptanoin and placebo periods. Triheptanoin was well tolerated. CONCLUSIONS: Triheptanoin does not prevent paroxysmal events in Alternating hemiplegia of childhood. We show the feasibility of a randomized placebo-controlled trial in this setting. TRIAL REGISTRATION: The study has been registered with clinicaltrials.gov ( NCT002408354 ) the 03/24/2015.

Evolution of structural neuroimaging biomarkers in a series of adult patients with Niemann-Pick type C under treatment.

BACKGROUND: Niemann-Pick type C (NPC) disease is a lysosomal storage disorder characterized by a wide clinical spectrum and non-specific conventional magnetic resonance imaging (MRI) signs. As substrate reduction therapy with miglustat is now used in almost all patients, its efficacy and the course of the disease are sometimes difficult to evaluate. Neuroimaging biomarkers could prove useful in this matter. We first performed a retrospective analysis of volumetric and diffusion tensor imaging (DTI) data on 13 adult NPC patients compared to 13 controls of similar age and sex. Eleven NPC patients were then studied using the same neuroimaging modalities over a mean of 5 years. The NPC composite score was used to evaluate disease severity. RESULTS: NPC patients showed atrophy in basal ganglia - pallidum (p = 0.029), caudate nucleus (p = 0.022), putamen (p = 0.002) and thalamus (p < 0.001) - cerebral peduncles (p = 0.003) and corpus callosum (p = 0.006), compared to controls. NPC patients also displayed decreased fractional anisotropy (FA) in several regions of interest - corona radiata (p = 0.015), internal capsule (p = 0.007), corpus callosum (p = 0.032) and cingulate gyrus (p = 0.002) - as well as a broad increase in radial diffusivity (p < 0.001), compared to controls. Over time, 3 patients worsened clinically, including 2 patients who interrupted treatment, while 8 patients remained stable. With miglustat, no significant volumetric change was observed but FA improved after 2 years in the corpus callosum and the corona radiata of NPC patients (n = 4; p = 0.029) - although that was no longer observed at further time points. CONCLUSION: This is the first study conducted on a series of adult NPC patients using two neuroimaging modalities and followed under treatment. It confirmed that NPC patients displayed cerebral atrophy in several regions of interest compared to controls. Furthermore, miglustat showed an early effect on diffusion metrics in treated patients. DTI can detect brain microstructure alterations caused by neurometabolic dysfunction. Its potential as a biomarker in NPC shall be further evaluated in upcoming therapeutic trials.

Early alterations of brain cellular energy homeostasis in Huntington disease models.

Brain energy deficit has been a suggested cause of Huntington disease (HD), but ATP depletion has not reliably been shown in preclinical models, possibly because of the immediate post-mortem changes in cellular energy metabolism. To examine a potential role of a low energy state in HD, we measured, for the first time in a neurodegenerative model, brain levels of high energy phosphates using microwave fixation, which instantaneously inactivates brain enzymatic activities and preserves in vivo levels of analytes. We studied HD transgenic R6/2 mice at ages 4, 8, and 12 weeks. We found significantly increased creatine and phosphocreatine, present as early as 4 weeks for phosphocreatine, preceding motor system deficits and decreased ATP levels in striatum, hippocampus, and frontal cortex of R6/2 mice. ATP and phosphocreatine concentrations were inversely correlated with the number of CAG repeats. Conversely, in mice injected with 3-nitroproprionic acid, an acute model of brain energy deficit, both ATP and phosphocreatine were significantly reduced. Increased creatine and phosphocreatine in R6/2 mice was associated with decreased guanidinoacetate N-methyltransferase and creatine kinase, both at the protein and RNA levels, and increased phosphorylated AMP-dependent protein kinase (pAMPK) over AMPK ratio. In addition, in 4-month-old knock-in Hdh(Q111/+) mice, the earliest metabolic alterations consisted of increased phosphocreatine in the frontal cortex and increased the pAMPK/AMPK ratio. Altogether, this study provides the first direct evidence of chronic alteration in homeostasis of high energy phosphates in HD models in the earliest stages of the disease, indicating possible reduced utilization of the brain phosphocreatine pool.

Pyruvate carboxylase deficiency: clinical and biochemical response to anaplerotic diet therapy.

A six-day-old girl was referred for severe hepatic failure, dehydratation, axial hypotonia, and both lactic acidosis and ketoacidosis. Biotin-unresponsive pyruvate carboxylase deficiency type B was diagnosed. Triheptanoin, an odd-carbon triglyceride, was administrated as a source for acetyl-CoA and anaplerotic propionyl-CoA. Although this patient succumbed to a severe infection, during the six months interval of her anaplerotic and biochemical management, the following important observations were documented: (1) the immediate reversal (less than 48 h) of major hepatic failure with full correction of all biochemical abnormalities, (2) on citrate supplementation, the enhanced export from the liver of triheptanoin's metabolites, namely 5 carbon ketone bodies, increasing the availability of these anaplerotic substrates for peripheral organs, (3) the demonstration of the transport of C5 ketone bodies-representing alternative energetic fuel for the brain-across the blood-brain barrier, associated to increased levels of glutamine and free gamma-aminobutyric acid (f-GABA) in the cerebrospinal fluid. Considering that pyruvate carboxylase is a key enzyme for anaplerosis, besides the new perspectives brought by anaplerotic therapies in those rare pyruvate carboxylase deficiencies, this therapeutic trial also emphasizes the possible extended indications of triheptanoin in various diseases where the citric acid cycle is impaired.