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Rett syndrome (RTT) is an early-onset neurodevelopmental disorder that almost exclusively affects girls and is totally disabling. Three genes have been identified that cause RTT: MECP2, CDKL5 and FOXG1. However, the etiology of some of RTT patients still remains unknown. Recently, next generation sequencing (NGS) has promoted genetic diagnoses because of the quickness and affordability of the method. To evaluate the usefulness of NGS in genetic diagnosis, we present the genetic study of RTT-like patients using different techniques based on this technology. We studied 1577 patients with RTT-like clinical diagnoses and reviewed patients who were previously studied and thought to have RTT genes by Sanger sequencing. Genetically, 477 of 1577 patients with a RTT-like suspicion have been diagnosed. Positive results were found in 30% by Sanger sequencing, 23% with a custom panel, 24% with a commercial panel and 32% with whole exome sequencing. A genetic study using NGS allows the study of a larger number of genes associated with RTT-like symptoms simultaneously, providing genetic study of a wider group of patients as well as significantly reducing the response time and cost of the study.

MECP2 duplication syndrome (MDS) is an X-linked neurodevelopmental disorder characterized by a severe to profound intellectual disability, early onset hypotonia and diverse psycho-motor and behavioural features. To date, fewer than 200 cases have been published. We report the clinical and molecular characterization of a Spanish MDS cohort that included 19 boys and 2 girls. Clinical suspicions were confirmed by array comparative genomic hybridization and multiplex ligation-dependent probe amplification (MLPA). Using, a custom in-house MLPA assay, we performed a thorough study of the minimal duplicated region, from which we concluded a complete duplication of both MECP2 and IRAK1 was necessary for a correct MDS diagnosis, as patients with partial MECP2 duplications lacked some typical clinical traits present in other MDS patients. In addition, the duplication location may be related to phenotypic severity. This observation may provide a new approach for genotype-phenotype correlations, and thus more personalized genetic counselling.

Hartnup disease is an autosomal recessive condition characterized by neutral aminoaciduria and behavioral problems. It is caused by a loss of B0 AT1, a neutral amino acid transporter in the kidney and intestine. CLTRN encodes the protein collectrin that functions in the transportation and activation of B0 AT1 in the renal apical brush bordered epithelium. Collectrin deficient mice have severe aminoaciduria. However, the phenotype associated with collectrin deficiency in humans has not been reported. Here we report two patients, an 11-year-old male who is hemizygous for a small, interstitial deletion on Xp22.2 that encompasses CLTRN and a 22-year-old male with a deletion spanning exons 1 to 3 of CLTRN. Both of them present with neuropsychiatric phenotypes including autistic features, anxiety, depression, compulsions, and motor tics, as well as neutral aminoaciduria leading to a clinical diagnosis of Hartnup disease and treatment with niacin supplementation. Plasma amino acids were normal in both patients. One patient had low 5-hydroxyindoleacetic acid levels, a serotoninergic metabolite. We explored the expression of collectrin in the murine brain and found it to be particularly abundant in the hippocampus, brainstem, and cerebellum. We propose that collectrin deficiency in humans can be associated with aminoaciduria and a clinical picture similar to that seen in Hartnup disease. Further studies are needed to explore the role of collectrin deficiency in the neurological phenotypes.

BACKGROUND: Next-generation sequencing (NGS) technology has allowed the promotion of genetic diagnosis and are becoming increasingly inexpensive and faster. To evaluate the utility of NGS in the clinical field, a targeted genetic panel approach was designed for the diagnosis of a set of inborn errors of metabolism (IEM). The final aim of the study was to compare the findings for the diagnostic yield of NGS in patients who presented with consistent clinical and biochemical suspicion of IEM with those obtained for patients who did not have specific biomarkers. METHODS: The subjects studied (n = 146) were classified into two categories: Group 1 (n = 81), which consisted of patients with clinical and biochemical suspicion of IEM, and Group 2 (n = 65), which consisted of IEM cases with clinical suspicion and unspecific biomarkers. A total of 171 genes were analyzed using a custom targeted panel of genes followed by Sanger validation. RESULTS: Genetic diagnosis was achieved in 50% of patients (73/146). In addition, the diagnostic yield obtained for Group 1 was 78% (63/81), and this rate decreased to 15.4% (10/65) in Group 2 (X2 = 76.171; p < 0.0001). CONCLUSIONS: A rapid and effective genetic diagnosis was achieved in our cohort, particularly the group that had both clinical and biochemical indications for the diagnosis.

Background Antioxidant therapy is a new therapeutical approach for patients with Friedreich ataxia. Aims To assess the effectiveness of long-term idebenone treatment in Friedreich ataxia patients. Methods An open-labelled prospective study. Ten paediatric patients (age range 8–18 years) and 14 adults (age range 18–46 years) with genetic diagnosis of Friedreich ataxia were treated with idebenone (5–20 mg/kg/day) for 3–5 years. Neurological evolution was evaluated using the International Cooperative Ataxia Rating Scale (ICARS), and cardiological outcomes using echocardiography. Results In paediatric patients, no significant differences were observed in ICARS scores and echocardiographic measurements when comparing baseline status and after 5 years of follow-up. Concerning adult cases, ICARS scores showed a significant increase in neurological dysfunctions during 3 years of therapy (Wilcoxon test, p=0.005), while echocardiographic measurements remained unchanged. Conclusions Our results indicate that longer-term idebenone treatment prevented progression of cardiomyopathy in both paediatric and adult patients, whereas its stabilizing effect on neurological dysfunction was present only in the paediatric population, mainly before puberty. This suggests that the age at which idebenone treatment is initiated may be an important factor in the effectiveness of the therapy.

Objective: Treatment of phenylketonuria (PKU) patients consists of a phenylalanine-restricted diet supplemented with a tyrosine-, vitamin- and oligoelement-enriched amino-acid mixture. Vitamins and oligoelements may be deficient when compliance with the supplemented special formula is poor. Plasma thiol concentrations (especially homocysteine) depend mainly on B-vitamin intake. Our aim was to evaluate the plasma thiol concentrations (homocysteine, cysteine and glutathione) and their determinants (methionine, cobalamin and folate) in PKU patients under dietary treatment compared with age-matched controls. Design and setting: Cross-sectional study performed in a tertiary care Hospital. Subjects: PKU (42) patients under dietary treatment compared with 42 age-matched controls. Interventions: Plasma total homocysteine, cysteine and glutathione were analyzed by HPLC with fluorescence detection. Plasma phenylalanine and methionine were analyzed by ion exchange chromatography. Serum folate and cobalamin were analyzed by radioimmunoassay procedures. Results: Total homocysteine concentrations were significantly lower in the PKU patients compared with the control group (Students t-test; P

Objective The study of the antioxidant status in female adolescents (N = 82) with anorexia nervosa, by the measurement of erythrocyte tocopherol concentration, and the determination of activities of the main antioxidant enzymes: superoxide dismutase, catalase, glutathione peroxidase, and glutathione reductase. Method Tocopherol was measured by high-performance liquid chromatography (HPLC) with ultraviolet (UV) detection, and antioxidant enzyme activities by spectrometric methods using a Cobas Fara automated centrifugal analyzer. Results Tocopherol was significantly decreased in the anorexic patients compared to reference values (p < .02). In 21% of patients, tocopherol levels were below the reference interval. Superoxide dismutase activity was significantly decreased (p < .0001), while catalase activity was increased (p < .0001). The activity of the glutathione system enzymes did not show significant differences between patients and controls. Discussion The deficient concentration of erythrocyte tocopherol together with the altered antioxidant enzyme activities suggest a certain degree of oxidative damage in anorexia nervosa owing to both factors deficient micronutrient intake and oxidative stress. © 1999 John Wiley & Sons, Inc. Int J Eat Disord 25:99–103, 1999.

The excess of genetic information in patients with Down syndrome (DS) produces an increase in the catalytic activity of superoxide dismutase (SOD1), an antioxidant enzyme coded on chromosome 21. It has been suggested that an increase in oxidative stress in DS patients may cause adverse effects in the cell membranes through the oxidation of polyunsaturated fatty acids (PUFAs). The aim of this study was to evaluate the cellular antioxidant system by determining the catalytic activity of the SOD1, glutathione peroxidase (GPx), catalase (CAT), and glutathione reductase (GR) enzymes and the concentrations of α-tocopherol in red blood cells (RBCs) in a group of 72 DS patients. The profile of fatty acids in the phospholipids of RBC membranes was also evaluated. The activity of the erythrocyte antioxidant enzymes is significantly higher in the DS group than in the control group (SOD1, 635 ± 70 U/g Hb vs 476 ± 67 U/g Hb; CAT, 1843 ± 250 U/g Hb vs 1482 ± 250 U/g Hb; GPx, 23.2 ± 5.3 U/g Hb vs 21.5 ± 3.6 U/g Hb; and GR, 9.32 ± 1.4 U/g Hb vs 6.9 ± 1.3 U/g Hb, respectively). No differences were observed in RBC α-tocopherol concentrations between the two groups studied. Long-chain n6 PUFA (C20:3n6, C20:4n6) concentrations were increased in DS patients, suggesting enhanced Δ-6-desaturase activity. The long-chain n3 PUFA (docosahexenoic acid) does not appear to be affected by increased oxidative stress, probably because of the existence of compensatory antioxidant mechanisms.

Selenium is an important trace element for brain function. Our objective was to analyse cerebrospinal fluid (CSF) selenium (Se) in 89 paediatric patients. We also studied correlations between Se and other biochemical variables (age, CSF protein concentrations and glutathione peroxidase activity and plasma Se values). Cerebrospinal fluid Se values showed a significant negative correlation with the age of patients (r = −0.476; p

The hallmarks of insulin action are the stimulation and suppression of anabolic and catabolic responses, respectively. These responses are orchestrated by the insulin pathway and are initiated by the binding of insulin to the insulin receptor, which leads to activation of the receptor’s intrinsic tyrosine kinase. Severe defects in the insulin pathway, such as in types A and B and advanced type 1 and 2 diabetes lead to severe insulin resistance, resulting in a partial or complete absence of response to exogenous insulin and other known classes of antidiabetes therapies. We have characterized a novel class of arylalkylamine vanadium salts that exert potent insulin-mimetic effects downstream of the insulin receptor in adipocytes. These compounds trigger insulin signaling, which is characterized by rapid activation of insulin receptor substrate-1, Akt, and glycogen synthase kinase-3 independent of insulin receptor phosphorylation. Administration of these compounds to animal models of diabetes lowered glycemia and normalized the plasma lipid profile. Arylalkylamine vanadium compounds also showed antidiabetic effects in severely diabetic rats with undetectable circulating insulin. These results demonstrate the feasibility of insulin-like regulation in the complete absence of insulin and downstream of the insulin receptor. This represents a novel therapeutic approach for diabetic patients with severe insulin resistance.

Objectives: To investigate the implications of the three main factors of the antioxidant system reported in relation to oxidative damage in phenylketonuric patients: selenium, ubiquinone-10 (Q10) and antioxidant enzymes over 3 years of metabolic follow-up. Design and methods: Longitudinal study of 46 phenylketonuric patients (age range: 6 months–34 years). Antioxidants were measured by atomic absorption spectrophotometric, chromatographic and spectrophotometric procedures. Results: Plasma selenium concentrations in phenylketonuria (PKU) were not different from those of a healthy population. Decreased plasma Q10 concentrations were mainly related to the dietary control and the age of patients. Erythrocyte catalase activity was significantly decreased in PKU while the other enzyme activities were not different from those of a healthy population. Conclusions: Selenium status is not impaired in phenylketonuric patients under dietary treatment. Q10 values tend to decrease with increased patient age. Catalase activity was negatively associated with plasma phenylalanine values.

Background: Low serum ubiquinone-10 concentrations have been described in phenylketonuric patients fed natural-protein-restricted diets. Such low concentrations may be related to increased free radical damage. Objective: We evaluated the relation between low serum ubiquinone-10 concentrations and other lipophilic antioxidants (tocopherol and retinol), selenium, glutathione peroxidase activity, and malondialdehyde concentrations as a marker of lipid peroxidation. Design: This was a cross-sectional study of 58 patients with phenylketonuria (aged 2-36 y; median: 13 y) under dietary treatment, 58 age-matched control subjects, and 30 children with moderate hyperphenylalaninemia fed unrestricted diets (aged 3-17 y; median: 7.5 y). Serum ubiquinone-10 concentrations were analyzed by HPLC with electrochemical detection. Serum retinol, serum tocopherol, and plasma malondialdehyde were analyzed by HPLC with ultraviolet detection. Results: A significant positive correlation was observed between ubiquinone-10 and tocopherol (r = 0.510, P < 0.001) in the patients with phenylketonuria. After the patients were stratified into 2 groups according to ubiquinone-10 values, significantly lower concentrations of tocopherol were observed in group I (low ubiquinone values) than in group 2 (normal ubiquinone values), the hyperphenylalaninemic children, and the control group. Plasma malondialdehyde concentrations were significantly higher in group 1 than in the other groups. No significant differences between groups 1 and 2 were observed in daily intakes of selenium, ascorbate, tocopherol, or retinol. Conclusions: Plasma lipid peroxidation seems to be increased in phenylketonuria. Low concentrations of ubiquinone-10 could be associated with either excessive tocopherol consumption or high malondialdehyde concentrations in patients with phenylketonuria.

Abnormal oxidative stress was observed in some inborn errors of metabolism owing to the accumulation of toxic metabolites leading to excessive free radical production and to the influence of restricted diets on the antioxidant status. Erythrocyte antioxidant enzymes activities and tocopherol concentrations were measured in a group of phenylketonuric (n = 42) and mild-hyperphenylalaninemic (n = 28) patients compared with 45 age-matched controls. We also determined plasma selenium levels in these groups. We also evaluated the possible relationship between antioxidant status and neuropsychological disorders. Erythrocyte glutathione peroxidase (GSH-Px) activity was significantly lower (P < 0.001) in both phenylketonuric and mild-hyperphenylalaninemic patients compared with the control group, but no differences were observed between the two groups of patients. Neuropsychological disturbances were more frequent in the group of PKU patients with low GSH-Px activity than in PKU patients with normal GSH-Px. Low GSH-Px activity might be explained in phenylketonuria as a result of a selenium deficiency caused by a poor selenium intake or absorption, but not in mild hyperphenylalaninemic patients with free diet. Selenium levels were normal in both groups of patients, so low glutathione peroxidase activity in both phenylketonuric and hyperphenylalaninemic groups might be influenced by other factors, such as the consequences of an unbalanced amino acid profile, common to both conditions.