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Journal of Inborn Errors of Metabolism and Screening, Volume: 5, Published: 2017
  • Editorial Letter to Special Issue on Phenylketonuria Editorial

    Cornejo, Verónica
  • Glycogen Storage Diseases: Next-Generation Medicine Editorial

    Derks, Terry G. J.; Souza, Carolina Fischinger Moura de
  • Alternative Therapies for PKU Original Article

    Spécola, Norma; Chiesa, Ana

    Abstract in English:

    Abstract The phenylalanine (PHE)-restricted diet has improved in quality and diversity over time and has proven to be effective in all patients. Nevertheless, this treatment imposes a heavy social and economic burden to patient and family and impacts quality of life. Sustained adherence to PHE restriction is difficult to maintain. Moreover, even patients with phenylketonuria (PKU) with normal intelligence quotient (IQ) have lower IQ than matched individuals without PKU and can have deficits in multiple other aspects of neuropsychological function, including cognitive and executive function, working memory. They can also have behavior problems, depression, and low self-esteem. In recent years, alternative treatments for PKU have been developed and their use has been indicated for some patients who are candidates for options besides traditional treatment. Sapropterindihydrochloride, large neutral amino acids, and glycomacropeptide are alternative treatment options in use for selected patients. The aim of this article is to review the current knowledge of these new approaches to PKU treatment.
  • Validation of a Multiplex Tandem Mass Spectrometry Method for the Detection of Selected Lysosomal Storage Diseases in Dried Blood Spots Original Article

    Ribas, Graziela Schmitt; Mari, Jurema Fátima De; Civallero, Gabriel; Souza, Heryk Motta de; Burin, Maira Graeff; Vargas, Carmen Regla; Giugliani, Roberto

    Abstract in English:

    Abstract Background: Interest in screening methods for lysosomal storage diseases (LSDs) has increased in recent years, since early diagnosis and treatment are essential to prevent or attenuate the onset of symptoms and the complications of these diseases. In the current work, we evaluated the performance of tandem mass spectrometry (MS/MS) for the detection of some LSDs, aiming the future use of this methodology for the screening of these disorders. Methods: Standard curves and quality control dried blood spots were assayed to evaluate the precision, linearity, and accuracy. A total of 150 controls were grouped according to age and subjected to measurement of lysosomal enzymes deficient in Niemann-Pick A/B, Krabbe, Gaucher, Fabry, Pompe, and Mucopolysaccharidosis type I diseases. Samples from 59 affected patients with a diagnosis of LSDs previously confirmed by fluorimetric methods were analyzed. Results: Data from standard calibration demonstrated good linearity and accuracy and the intra- and interassay precisions varied from 1.17% to 11.60% and 5.39% to 31.24%, respectively. Except for galactocerebrosidase and ?-l-iduronidase, enzyme activities were significantly higher in newborns compared to children and adult controls. Affected patients presented enzymatic activities significantly lower compared to all control participants. Conclusion: Our results show that MS/MS is a promising methodology, suitable for the screening of LSDs, but accurate diagnoses will depend on its correlation with other biochemical and/or molecular analyses.
  • The Challenge of Diagnosis and Indication for Treatment in Fabry Disease Original Article

    Curiati, Marco A.; Aranda, Carolina S.; Kyosen, Sandra O.; Varela, Patricia; Pereira, Vanessa G.; D’Almeida, Vania; Pesquero, João B.; Martins, Ana M.

    Abstract in English:

    Abstract Fabry disease, caused by deficient alpha-galactosidase A lysosomal enzyme activity, remains challenging to health-care professionals. Laboratory diagnosis in males is carried out by determination of alpha-galactosidase A activity; for females, enzymatic activity determination fails to detect the disease in about two-thirds of the patients, and only the identification of a pathogenic mutation in the GLA gene allows for a definite diagnosis. The hurdle to be overcome in this field is to determine whether a mutation that has never been described determines a ‘‘classic’’ or ‘‘nonclassic’’ phenotype, because this will have an impact on the decision-making for treatment initiation. Besides the enzymatic determination and GLA gene mutation determination, researchers are still searching for a good biomarker, and it seems that plasma lyso-Gb3 is a useful tool that correlates to the degree of substrate storage in organs. The ideal time for treatment initiation for children and nonclassic phenotype remains unclear.
  • Chilean Nutrition Management Protocol for Patients With Phenylketonuria Original Article

    Castro, Gabriela; Hamilton, Valerie; Cornejo, Verónica

    Abstract in English:

    Abstract Since neonatal screening and early nutritional treatment began, it has been possible to reverse the neurological damage that phenylketonuria (PKU) causes. Scientific evidence gathered over more than 50 years on the monitoring of individuals with PKU indicates that a phenylalanine level of about 6 mg/dL (360 µmol/L) is ideal and points to the necessity of starting a long-term phenylalanine-restricted diet in which blood phenylalanine level should stay between 2 and 6 mg/dL (120-360 µmol/L). This article aims to establish the general basis for proper monitoring of people with PKU and provide a useful tool for clinicians overseeing treatment. We hope to establish similar criteria throughout Latin America and create a uniform protocol in order to have comparative monitoring results for the region.
  • Pulmonary Arterial Hypertension in Glycogen Storage Disease Type I Original Article

    Torok, Rachel D.; Austin, Stephanie L.; Britt, Lisa K.; Abdenur, Jose E.; Kishnani, Priya S.; Wechsler, Stephanie B.

    Abstract in English:

    Abstract Pulmonary arterial hypertension (PAH) is a rare and highly fatal disease that has been reported in 8 patients with glycogen storage disease type I (GSDI). We describe an additional case of an acute presentation of PAH in a 14-year-old patient with GSDI, which was successfully treated with inhaled nitric oxide and sildenafil. We investigated the incidence of PAH in 28 patients with GSDI on routine echocardiography and found no evidence of PAH and no significant cardiac abnormalities. This study highlights that PAH is a rare disease overall, but our case report and those previously described suggest an increased incidence in patients with GSDI. Should cardiopulmonary symptoms develop, clinicians caring for patients with GSDI should have a high degree of suspicion for acute PAH and recognize that prompt intervention can lead to survival in this otherwise highly fatal disease.
  • Hepatic Glycogen Storage Diseases Toward One Global Collaborative Network Original Article

    Derks, Terry G. J.; Nemeth, Antal; Adrian, Katrin; Arnell, Henrik; Roskjær, Ann Bech; Beijer, Eva; Boekhorst, Sebastiaan te; Heidenborg, Carina; Landgren, Marcus; Nilsson, Mikael; Papadopoulou, Domniki; Ross, Katalin; Sjöqvist, Elisabeth; Stachelhaus-Theimer, U; Steuerwald, Ulrike; Törnhage, Carl-Johan; Weinstein, David A.

    Abstract in English:

    Abstract The third international meeting of the Scandinavian Association for Glycogen Storage Disease focused on hepatic glycogen storage disease and was organized for health-care professionals, patient representatives, and representatives from the industry. This report highlights dilemmas in dietary management, differences in monitoring strategies, and challenges with rare disease care, research, and patient participation.
  • Impact of Enzyme Replacement Therapy in a Patient Younger Than 2 Years Diagnosed With Maroteaux-Lamy Syndrome (MPS VI) Original Article

    Guio, Johanna Acosta; AdolfoGiraldo-Ospina, Gustavo

    Abstract in English:

    Abstract Introduction: Mucopolysaccharidosis type VI, also known as Maroteaux-Lamy syndrome (#OMIM 253200), is a rare autosomal recessive genetic disorder due to deficient activity of the enzyme N-acetylgalactosamine 4-sulfatase (arylsulfatase B) required for the breakdown of dermatan sulfate and chondroitin sulfate. Patient: Report of a female patient started on enzyme replacement therapy at 17 months of age. At the time of diagnosis (14 months), the patient presented mild corneal opacity and significant thoracolumbar kyphosis, but no visceral involvement or growth arrest. At 73 months of treatment, weight was normal, although the patient was in a low height percentile. The patient showed adequate neural development, with improvement in lumbar spine and joint involvement. Corneal compromise or valvular disease progression was not evident. Conclusion: Early and timely diagnosis and treatment with enzyme replacement therapy are essential, as the means to change the natural history of the disease, avoiding comorbidities and improving final prognosis.
  • Epilepsy and Mitochondrial Dysfunction: A Single Center’s Experience Original Article

    Saneto, Russell P.

    Abstract in English:

    Abstract Epilepsy is a common manifestation of mitochondrial disease. In a large cohort of children and adolescents with mitochondrial disease (n = 180), over 48% of patients developed seizures. The majority (68%) of patients were younger than 3 years and medically intractable (90%). The electroencephalographic pattern of multiregional epileptiform discharges over the left and right hemisphere with background slowing occurred in 62%. The epilepsy syndrome, infantile spasms, was seen in 17%. Polymerase ? mutations were the most common genetic etiology of seizures, representing Alpers-Huttenlocher syndrome (14%). The severity of disease in those patients with epilepsy was significant, as 13% of patients experienced early death. Simply the loss of energy production cannot explain the development of seizures or all patients with mitochondrial dysfunction would have epilepsy. Until the various aspects of mitochondrial physiology that are involved in proper brain development are understood, epilepsy and its treatment will remain unsatisfactory.
  • Nutritional Status and Body Composition in Patients With Hepatic Glycogen Storage Diseases Treated With Uncooked Cornstarch—A Controlled Study Original Article

    Santos, Bruna B. dos; Nalin, Tatiéle; Grokoski, Kamila C.; Perry, Ingrid D. S.; Refosco, Lilia F.; Vairo, Filippo P.; Souza, Carolina F. M.; Schwartz, Ida V. D.

    Abstract in English:

    Abstract Hepatic glycogen storage diseases (GSDs) are genetic diseases associated with fasting hypoglycemia. Periodic intake of uncooked cornstarch is one of the treatment strategies available for those disorders. For reasons that are still not clear, patients with hepatic GSDs may be overweight. Aims: To assess nutritional status and body composition in patients with hepatic GSDs receiving uncooked cornstarch. Methods: The sample included 25 patients with hepatic GSD (type Ia = 14; Ib = 6; III = 3; IX? = 1; IX? = 1), with a median age of 11.0 years (interquartile range [IQR] = 9.0-17.5), matched by age and gender with 25 healthy controls (median age = 12.0 years, IQR = 10.0-17.5). Clinical, biochemical, and treatment-related variables were obtained from medical records. Nutritional status and body composition were prospectively evaluated by bioelectrical impedance. Results: Patients and controls did not differ with regard to age and gender. Height was significantly reduced in patients (median = 1.43 m, IQR = 1.25-1.54) in comparison to controls (median = 1.54 m, IQR = 1.42-1.61; P = .04). Body mass index for age z-score and fat mass percentage were higher in patients (median = 1.84, IQR = 0.55-3.06; and 27.5%, IQR = 22.6-32.0, respectively) than in controls (median = 0.86, IQR = ?0.55 to 1.82; P = .04 and 21.1%, IQR = 13.0-28.3; P = .01, respectively). When patients were stratified by type, those with GSD Ia had significantly higher adiposity (median fat mass = 28.7%, IQR = 25.3-32.9) than those with GSD III and GSD IX?/? (median fat mass = 20.9%, IQR = 14.9-22.6; P = .02). Conclusions: Our findings suggest that patients with hepatic GSD on treatment with cornstarch, especially those with GSD Ia, exhibit abnormalities in nutritional status and body composition, such as short stature and a trend toward overweight and obesity.
  • The Incidence of Transient Neonatal Tyrosinemia Within a Mexican Population Original Article

    Zea-Rey, Alexandra V.; Cruz-Camino, Héctor; Vazquez-Cantu, Diana L.; Gutiérrez-García, Valeria M.; Santos-Guzmán, Jesús; Cantú-Reyna, Consuelo

    Abstract in English:

    Abstract Transient neonatal tyrosinemia (TNT) is a form of hypertyrosinemia produced by the immaturity of 4-hydroxyphenylpyruvate dioxygenase (4-HPPD), a high intake of phenylalanine and tyrosine, and a relative ascorbic acid deficiency. Our objectives are to determine the incidence of TNT in Mexican newborns and to correlate it based on their sex, gestational age, and weight for gestational age to determine whether these are risk factors that predict the development of TNT. A cross-sectional descriptive study was conducted from January 2006 to August 2017. We analyzed 175 976 of newborn screening reports and found that the overall incidence of TNT was 1 (0.29%) in 342 newborns. It is more prevalent in preterm infants and in small for gestational age newborns (0.35%).The TNT incidence was determined in this Mexican population, and it was established as the most frequently occurring amino acid defect. We propose that pediatricians intentionally search for this pathology to offer patients access to adequate and timely treatment.
  • Newborn Screening for Lysosomal Storage Disorders in Belgium The Importance of Sex- and Age-Dependent Reference Ranges Original Article

    Eyskens, Francois; Devos, Sylvie

    Abstract in English:

    Abstract Lysosomal storage disorders (LSDs) are a group of metabolic disorders with various clinical presentations, which complicate diagnosis. A pilot study was performed to test the appropriateness and effectiveness of the newborn screening method for Pompe disease, Fabry disease and mucopolysaccharidosis (MPS) I in dried blood spots using liquid chromatography–tandem mass spectrometry. Around 20 000 newborn samples were analyzed for 3 lysosomal enzyme activities: ?-glucosidase (deficient in Pompe disease), ?-galactosidase (deficient in Fabry disease) and ?-iduronidase (IDUA, deficient in MPS I). Data were used for statistical analysis and to establish sex- and age-dependent reference ranges. Statistically significant higher ?-glucosidase, ?-galactosidase, and IDUA enzyme activities were observed in female newborns compared to male newborns. Newborns with a higher gestational age have a statistically significant lower ?-glucosidase, ?-galactosidase, and IDUA enzyme activities compared to newborns with a lower gestational age. For the first time, the data of a large-scale LSD study were used to assess statistical differences in enzyme activity in the newborn population, and these data highlight the importance of using reference intervals for lysosomal enzyme activities in function of sex and gestational age.
  • Isolated and Combined Remethylation Disorders: Biochemical and Genetic Diagnosis and Pathophysiology Review

    Richard, Eva; Brasil, Sandra; Leal, Fátima; Navarrete, Rosa; Vega, Ana; Ecay, María Jesús; Desviat, Lourdes R.; Pérez-Cerda, Celia; Ugarte, Magdalena; Merinero, Begoña; Pérez, Belén

    Abstract in English:

    Abstract Genetic defects affecting the remethylation pathway cause hyperhomocysteinemia. Isolated remethylation defects are caused by mutations of the 5, 10-methylenetetrahydrofolate reductase (MTHFR), methionine synthase reductase(MTRR), methionine synthase(MTR), and MMADHC genes, and combined remethylation defects are the result of mutations in genes involved in the synthesis of either methylcobalamin or adenosylcobalamin, that is, the active cofactors of MTRR and methylmalonyl-CoA mutase. Diagnosis is based on the biochemical analysis of amino acids, homocysteine, propionylcarnitine, methylmalonic acid, S-adenosylmethionine, and 5-methylentetrahydrofolate in physiological fluids. Gene-by-gene Sanger sequencing has long been the gold standard genetic analysis for confirming the disorder and identifying the gene involved, but massive parallel sequencing is now being used to examine all those potentially involved in one go. Early treatment to rescue metabolic homeostasis is based on the following of an appropriate diet, betaine administration, and, in some cases, oral or intramuscular administration of vitamin B12 or folate. Elevated ROS levels, apoptosis, endoplasmic reticulum (ER) stress, the activation of autophagy, and alterations in Ca2+ homeostasis may all contribute toward the pathogenesis of the disease. Pharmacological agents to restore the function of the ER and mitochondria and/or to reduce oxidative stress-induced apoptosis might provide novel ways of treating patients with remethylation disorders.
  • Mitochondrial Disease and Anesthesia Review

    Hsieh, Vincent C.; Krane, Elliot J.; Morgan, Philip G.

    Abstract in English:

    Abstract It is increasingly common for children with mitochondrial disease to undergo surgery and anesthesia. Although many different anesthetics have been used successfully for these patients, serious, unexpected complications have occurred during and following anesthetic exposure. This has led to the widespread opinion among anesthesiologists that mitochondrial patients are at increased risk from the stress of surgery and anesthesia. Defects in function of the mitochondrial electron transport chain can lead to striking hypersensitivity to volatile anesthetics in children. Despite this striking finding, the connection between mitochondrial function and response to anesthetics is unknown. We review here the anesthetic considerations for patients with mitochondrial defects. In addition, we present an approach to anesthetic care of these patients at our institutions.
  • Strategies for Successful Long-Term Engagement of Adults With Phenylalanine Hydroxylase Deficiency Returning to the Clinic Review

    Thomas, Janet; Nguyen-Driver, Mina; Bausell, Heather; Breck, Jane; Zambrano, Javier; Birardi, Vanessa

    Abstract in English:

    Abstract Nearly half of all patients diagnosed with phenylalanine hydroxylase (PAH) deficiency, also known as phenylketonuria, are lost to follow-up (LTFU); most are adults who stopped attending clinic after the age of 18 years. To understand why adult patients with PAH deficiency disengage from their clinic, a focus group of 8 adults with PAH deficiency who had been LTFU for 2 or more years was held in March 2016. Ten clinicians observed the focus group and discussed strategies for successfully reengaging adult patients and encouraging lifelong management of PAH deficiency. Four strategies were proposed: (1) create a safe, supportive environment, (2) acknowledge patients as partners in their care, (3) develop individualized management plans, and (4) provide patients with additional resources. These strategies provide a framework to motivate change in clinical practice to meet the unique needs of adults with PAH deficiency.
  • The Link Between Hyperhomocysteinemia and Hypomethylation: Implications for Cardiovascular Disease Review Article

    Barroso, Madalena; Handy, Diane E.; Castro, Rita

    Abstract in English:

    Abstract Increased levels of homocysteine have been established as a risk factor for cardiovascular disease (CVD) by mechanisms still incompletely defined. S-Adenosylhomocysteine (SAH) is the metabolic precursor of homocysteine that accumulates in the setting of hyperhomocysteinemia and is a negative regulator of most cell methyltransferases. Several observations, summarized in the current review, support the concept that SAH, rather than homocysteine, may be the culprit in the CVD risk that has been associated with hyperhomocysteinemia. This review examines the biosynthesis and catabolism of homocysteine and how these pathways regulate accumulation of SAH. In addition, the epidemiological and experimental links between hyperhomocysteinemia and CVD are discussed, along with the evidence suggesting a role for SAH in the disease. Finally, the effects of SAH on the hypomethylation of DNA, RNA, and protein are examined, with an emphasis on how specific molecular targets may be mediators of homocysteine-associated vascular disease.
  • Gene Therapy for Lysosomal Storage Disorders: Recent Advances and Limitations Review Article

    Gonzalez, Esteban Alberto; Baldo, Guilherme

    Abstract in English:

    Abstract Lysosomal storage disorders (LSDs) are a group of diseases with multisystemic features. Current treatments have limitations and gene therapy arises as a promising treatment option. Here, we discuss some of the most recent studies for gene therapy in LSD, vectors used, and outcomes. In particular, the approaches used in animal models aiming to correct the central nervous system, the eye, and the bones are highlighted. Finally, we discuss the recent reports of clinical trials using this technology for these diseases. We conclude that gene therapy for LSD has gathered a substantial amount of evidence from animal models to know its potential and limitations. First evidences from clinical trials using both adeno-associated and lentiviral vectors show that this approach is safe and efficient and therefore could provide an effective treatment for several LSD in the near future.
  • Homocysteine and Psychiatric Disorders Review Article

    Silva, Vanessa Cavalcante da; Oliveira, Allan Chiaratti de; D’Almeida, Vânia

    Abstract in English:

    Abstract Psychiatric disorders are highly prevalent all over the world with a great impact on public health. Altered homocysteine metabolism is implicated in the pathogenesis of many of these disorders, as it can interfere in normal methylation of subcellular components, promote neuroexcitotoxicity, and induce oxidative stress and inflammation. There are cumulative data implicating these mechanisms in the development of autism, schizophrenia, depression, bipolar disorder, and Alzheimer disease. Altered homocysteine metabolism is multifactorial in its origin. On one hand, genetic factors act as predisposing factors through brain development and function, and on the other hand, environmental factors give the opportunity for nutritional interventions improving metabolic status and possibly also clinical parameters. This article provides a review on the association of 1-carbon metabolism and autism, schizophrenia, depression, bipolar disorder, and dementia and goes through studies on the role of different cofactors and metabolites involved in this pathway.
  • Arginine and Citrulline for the Treatment of MELAS Syndrome Review Article

    El-Hattab, Ayman W.; Almannai, Mohammed; Scaglia, Fernando

    Abstract in English:

    Abstract Mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS) syndrome is a maternally inherited mitochondrial disease with a broad spectrum of manifestations. In addition to impaired energy production, nitric oxide (NO) deficiency occurs in MELAS syndrome and leads to impaired blood perfusion in microvasculature that can contribute to several complications including stroke-like episodes, myopathy, and lactic acidosis. The supplementation of NO precursors, L-arginine and L-citrulline, increases NO production and hence can potentially have therapeutic utility in MELAS syndrome. L-citrulline raises NO production to a greater extent than L-arginine; therefore, L-citrulline may have a better therapeutic effect. The clinical effect of L-citrulline has not yet been studied and clinical studies on L-arginine, which are limited, only evaluated the stroke-like episodes’ aspects of the disease. Controlled studies are still needed to assess the clinical effects of L-arginine and L-citrulline on different aspects of MELAS syndrome.
  • Mechanistic Bases of Neurotoxicity Provoked by Fatty Acids Accumulating in MCAD and LCHAD Deficiencies Review Article

    Amaral, Alexandre U.; Cecatto, Cristiane; Silva, Janaína C. da; Wajner, Alessandro; Wajner, Moacir

    Abstract in English:

    Abstract Fatty acid oxidation defects (FAODs) are inherited metabolic disorders caused by deficiency of specific enzyme activities or transport proteins involved in the mitochondrial catabolism of fatty acids. Medium-chain fatty acyl-CoA dehydrogenase (MCAD) and long-chain 3-hydroxyacyl-CoA dehydrogenase (LCHAD) deficiencies are relatively common FAOD biochemically characterized by tissue accumulation of medium-chain fatty acids and long-chain 3-hydroxy fatty acids and their carnitine derivatives, respectively. Patients with MCAD deficiency usually have episodic encephalopathic crises and liver biochemical alterations especially during crises of metabolic decompensation, whereas patients with LCHAD deficiency present severe hepatopathy, cardiomyopathy, and acute and/or progressive encephalopathy. Although neurological symptoms are common features, the underlying mechanisms responsible for the brain damage in these disorders are still under debate. In this context, energy deficiency due to defective fatty acid catabolism and hypoglycemia/hypoketonemia has been postulated to contribute to the pathophysiology of MCAD and LCHAD deficiencies. However, since energetic substrate supplementation is not able to reverse or prevent symptomatology in some patients, it is presumed that other pathogenetic mechanisms are implicated. Since worsening of clinical symptoms during crises is accompanied by significant increases in the concentrations of the accumulating fatty acids, it is conceivable that these compounds may be potentially neurotoxic. We will briefly summarize the current knowledge obtained from patients with these disorders, as well as from animal studies demonstrating deleterious effects of the major fatty acids accumulating in MCAD and LCHAD deficiencies, indicating that disruption of mitochondrial energy, redox, and calcium homeostasis is involved in the pathophysiology of the cerebral damage in these diseases. It is presumed that these findings based on the mechanistic toxic effects of fatty acids may offer new therapeutic perspectives for patients affected by these disorders.
  • Hampered Vitamin B12 Metabolism in Gaucher Disease? Review Article

    Hannibal, Luciana; Siebert, Marina; Basgalupp, Suelen; Vario, Filippo; Spiekerkoetter, Ute; J. Blom, Henk

    Abstract in English:

    Abstract Untreated vitamin B12 deficiency manifests clinically with hematological abnormalities and combined degeneration of the spinal cord and polyneuropathy and biochemically with elevated homocysteine (Hcy) and methylmalonic acid (MMA). Vitamin B12 metabolism involves various cellular compartments including the lysosome, and a disruption in the lysosomal and endocytic pathways induces functional deficiency of this micronutrient. Gaucher disease (GD) is characterized by dysfunctional lysosomal metabolism brought about by mutations in the enzyme beta-glucocerebrosidase (Online Mendelian Inheritance in Man (OMIM): 606463; Enzyme Commission (EC) 3.2.1.45, gene: GBA1). In this study, we collected and examined available literature on the associations between GD, the second most prevalent lysosomal storage disorder in humans, and hampered vitamin B12 metabolism. Results from independent cohorts of patients show elevated circulating holotranscobalamin without changes in vitamin B12 levels in serum. Gaucher disease patients under enzyme replacement therapy present normal levels of Hcy and MMA. Although within the normal range, a significant increase in Hcy and MMA with normal serum vitamin B12 was documented in treated GD patients with polyneuropathy versus treated GD patients without polyneuropathy. Thus, a functional deficiency of vitamin B12 caused by disrupted lysosomal metabolism in GD is a plausible mechanism, contributing to the neurological form of the disorder but this awaits confirmation. Observational studies suggest that an assessment of vitamin B12 status prior to the initiation of enzyme replacement therapy may shed light on the role of vitamin B12 in the pathogenesis and progression of GD.
  • Use of Idebenone for the Treatment of Leber’s Hereditary Optic Neuropathy Review Article

    Catarino, Claudia B.; Klopstock, Thomas

    Abstract in English:

    Abstract Leber’s hereditary optic neuropathy (LHON) is one of the most frequent mitochondrial disorders. It is caused by mutations in genes of the mitochondrial DNA coding for subunits of the respiratory chain and leads to severe bilateral vision loss, from which spontaneous recovery is infrequent. Retinal ganglion cells show a selective vulnerability to mitochondrial dysfunction in LHON. Idebenone is the first medication approved for LHON. It is a short-chain benzoquinone, which is an analogue of coenzyme Q10, but with distinct properties and mechanisms of action. Idebenone is a potent antioxidant and inhibitor of lipid peroxidation. Importantly, it facilitates electron flux directly to complex III, bypassing the dysfunctional complex I of the mitochondrial respiratory chain, thereby increasing adenosine triphosphate (ATP) production. In the Rescue of Hereditary Optic Disease Outpatient Study (RHODOS) randomized placebo-controlled clinical trial, 85 patients with LHON were enrolled, in the first 5 years after symptom onset, and randomized to either idebenone 900 mg/d for 6 months or placebo. Idebenone was well tolerated, and although the prespecified primary end point (best recovery in visual acuity [VA]) did not reach statistical significance, all secondary end points (change in best VA, change of VA of best eye at baseline, and change of VA in all eyes) showed a trend toward visual recovery in favor of idebenone. An increasing body of evidence shows that idebenone is effective and safe for the treatment of patients with LHON, including a large retrospective open-label study, several case reports and case series, an expanded access program, and ongoing post-authorization clinical studies. Here, we review the literature on idebenone for the treatment of patients with LHON.
  • Potential Therapeutic Targets of the Endocannabinoid System in Common Neurodegenerative Disorders and Organic Acidemias Review Article

    Aguilera, Gabriela; Santamaria, Abel

    Abstract in English:

    Abstract The cannabinoid chemistry is currently being addressed in preclinical approaches as a viable therapeutic alternative for the management of a wide range of signs, symptoms, and some biochemical hallmarks of many neurological pathologies (such as neuroinflammation and neurodegeneration). This clinical orientation is grounded on the consistent promissory profile that cannabinoid compounds have shown, and the great necessity of feasible options to undergo such disorders. Even though at early research stages, metabolic disorders are starting to rise as potential targets of cannabinoid alternatives; approaches in this term could, in turn, aim to modulate the endocannabinoid response for therapeutic purposes. This review recalls the pathologic scenarios endured in the course of neurological diseases of high occurrence and the most typical metabolic disorders, while discussing the neuroprotective mechanisms of cannabinoid agonists in the central nervous system, and the potential targets of the endocannabinoid system and metabolic disorders.
  • Coenzyme Q10 in the Treatment of Mitochondrial Disease Original Manuscript

    Neergheen, Viruna; Chalasani, Annapurna; Wainwright, Luke; Yubero, Delia; Montero, Raquel; Artuch, Rafael; Hargreaves, Iain

    Abstract in English:

    Abstract Currently, there is a paucity of available treatment strategies for oxidative phosphorylation disorders. Coenzyme Q10 (CoQ10) and related synthetic quinones are the only agents to date that have proven to be beneficial in the treatment of these heterogeneous disorders. The therapeutic efficacy of CoQ10 is not restricted to patients with an underlying CoQ10 deficiency and is thought to result from its ability to restore electron flow in the mitochondrial respiratory chain (MRC) as well as to increase the cellular antioxidant capacity. At present, however, there is no consensus on the appropriate dosage or therapeutic plasma level of CoQ10, and this information will be required before CoQ10 can be utilized effectively in the treatment of mitochondrial disease. The following review will outline our current knowledge on the use of CoQ10 in the treatment of MRC disorders and primary CoQ10 deficiencies.
  • Hyperprolinemia Type IA: Benign Metabolic Anomaly or a Trigger for Brain Dysfunction? Original Manuscript

    Pavone, Piero; Praticò, Andrea D.; Sorge, Giovanni; Meli, Concetta; Ruggieri, Martino; Rizzo, Renata; Fiumara, Agata

    Abstract in English:

    Abstract Objective: Hyperprolinemia type I (HPI) is a rare and inherited autosomal recessive disorder caused by proline oxidase deficiency. Hyperprolinemia type 1 is biochemically defined as high plasma proline levels without urinary ?-1-pyrroline-5-carboxylate excretion. Hyperprolinemia type 1 has been considered a benign metabolic disorder, but a relationship with neurological disorders has recently been suggested. Study Design: We retrospectively analyzed plasma amino acid values obtained by amino acid analysis from 10 030 children admitted for neurological reasons during the years 1996 to 2010 at the Regional Sicilian Centre for Metabolic Diseases. Patients with proline levels above the normal range of 129 to 245 ?M were identified. Results: Only 2 children showed high levels of proline (450-480 ?M and 380-470 ?M, respectively), but their disorders (tubercular neuroencephalitis and progressive mitochondrial encephalopathy) did not seem to be related to hyperprolinemia as a causative factor. Conclusion: The question of HPI as benign metabolic anomaly or as a direct cause of brain damage is still open. Since HPI is rare, other observations on this regard are necessary.
  • Impact of Elosulfase Alfa on Pain in Patients with Morquio A Syndrome over 52 Weeks: MOR-008: A Randomized, Double-Blind, Pilot Study Original Manuscript

    Treadwell, Marsha; Harmatz, Paul R.; Burton, Barbara K.; Mitchell, John J.; Muschol, Nicole; Jones, Simon A.; Pastores, Gregory M.; Lau, Heather A.; Sparkes, Rebecca; Sutton, V. Reid; Meesen, Bianca; Haller, Christine A.; Shaywitz, Adam J.; Gold, Jeffrey I.

    Abstract in English:

    Abstract Patients with mucopolysaccharidosis (MPS), and Morquio A syndrome (MPS IVA) in particular, often report substantial pain burden. MOR-008 was a randomized, double-blind, pilot study assessing the safety and efficacy, including impact on patient-reported pain, of 52 weeks of treatment with elosulfase alfa (at a dose of 2.0 or 4.0 mg/kg/week) in patients with Morquio A syndrome (?7 years old). Assessment of pain at baseline revealed that patients (N = 25) had a mean number of pain locations of 5.7, mean pain intensity score of 4.6 (indicative of medium pain), and a mean number of selected pain descriptors of 7.4 words. Treatment with elosulfase alfa improved subjective pain score (reduced to 3.2), pain locations (reduced by a mean of 1 location), and pain descriptor words (reduced to 4.9 words) over 1 year (52 weeks), suggesting that elosulfase alfa can reduce pain in some patients with Morquio A.
  • Clinical Trials in Mitochondrial Disease: An Update on EPI-743 and RP103 Original Manuscript

    Enns, Gregory M.; Cohen, Bruce H.

    Abstract in English:

    Abstract Mitochondrial dysfunction results in the production of an abnormally high amount of reactive oxygen and nitrogen species, which results in redox imbalance and glutathione deficiency. Therapeutics such as EPI-743 (?-tocotrienol quinone) and RP103 (cysteamine bitartrate) have the theoretical potential to improve redox imbalance by increasing intracellular glutathione and are currently under investigation in multiple clinical trials. This review provides an update on the use of these compounds in clinical trials related to primary and secondary mitochondrial disorders. These clinical trials have not only provided hope to affected patients and their families and caregivers, but also will serve as important stepping stones for further studies as our understanding of mitochondrial disease pathogenesis continues to improve.
Latin American Society Inborn Errors and Neonatal Screening (SLEIMPN); Instituto Genética para Todos (IGPT) Rua Ramiro Barcelos, 2350, CEP: 90035-903, Porto Alegre, RS - Brasil, Tel.: 55-51-3359-6338, Fax: 55-51-3359-8010 - Porto Alegre - RS - Brazil
E-mail: rgiugliani@hcpa.edu.br