[Hepatic glycogen storage diseases: Symptoms, management and associated mutations]. / Enfermedades por depósito de glucógeno hepático: Clínica, manejo y mutaciones asociadas.

Glycogen storage diseases (GSD) are rare diseases derived from altered glycogen metabolism. This leads to glycogen storage in different organs such as muscle, kidney, and liver, resulting in a variety of clinical manifestations. GSD with liver involvement are classified into types I, III, IV, VI, and IX, depending on the enzymes affected. They are clinically characterized by hypoglycemia and hepato megaly as cardinal signs. Their diagnosis is initially based on clinical manifestations and laboratory test results. Nevertheless, diagnostic certainty requires a genetic study that identifies the specific mutation. Multiple mutations have been associated with each GSD. In Chile, since patients often lack the genetic study, the GSD genetic local characteristics are unknown. The treatment is based on dietary restrictions modulated according to the identified mutation. Today, the international consen sus indicates that early diagnosis allows better metabolic control and improves the patient's quality of life and prognosis. In this review, the information on GSD with liver involvement is updated to optimize the diagnosis, treatment, and follow-up of these patients, emphasizing specific nutritional and gastroenterological management.

Mitochondrial and Metabolic Myopathies.

PURPOSE OF REVIEW: This article provides an overview of mitochondrial and metabolic biology, the genetic mechanisms causing mitochondrial diseases, the clinical features of mitochondrial diseases, lipid myopathies, and glycogen storage diseases, all with a focus on those syndromes and diseases associated with myopathy. Over the past decade, advances in genetic testing have revolutionized patient evaluation. The main goal of this review is to give the clinician the basic understanding to recognize patients at risk of these diseases using the standard history and physical examination. RECENT FINDINGS: Primary mitochondrial disease is the current designation for the illnesses resulting from genetic mutations in genes whose protein products are necessary for mitochondrial structure or function. In most circumstances, more than one organ system is involved in mitochondrial disease, and the value of the classic clinical features as originally described early in the history of mitochondrial diseases has reemerged as being important to identifying patients who may have a primary mitochondrial disease. The use of the genetic laboratory has become the most powerful tool for confirming a diagnosis, and nuances of using genetic results will be discussed in this article. Treatment for mitochondrial disease is symptomatic, with less emphasis on vitamin and supplement therapy than in the past. Clinical trials using pharmacologic agents are in progress, with the field attempting to define proper goals of treatment. Several standard accepted therapies exist for many of the metabolic myopathies. SUMMARY: Mitochondrial, lipid, and glycogen diseases are not uncommon causes of multisystem organ dysfunction, with the neurologic features, especially myopathy, occurring as a predominant feature. Early recognition requires basic knowledge of the varied clinical phenotypes before moving forward with a screening evaluation and possibly a genetic evaluation. Aside from a few specific diseases for which there are recommended interventions, treatment for the majority of these disorders remains symptomatic, with clinical trials currently in progress that will hopefully result in standard treatments.

A novel image-based high-throughput screening assay discovers therapeutic candidates for adult polyglucosan body disease.

Glycogen storage disorders (GSDs) are caused by excessive accumulation of glycogen. Some GSDs [adult polyglucosan (PG) body disease (APBD), and Tarui and Lafora diseases] are caused by intracellular accumulation of insoluble inclusions, called PG bodies (PBs), which are chiefly composed of malconstructed glycogen. We developed an APBD patient skin fibroblast cell-based assay for PB identification, where the bodies are identified as amylase-resistant periodic acid-Schiff's-stained structures, and quantified. We screened the DIVERSet CL 10 084 compound library using this assay in high-throughput format and discovered 11 dose-dependent and 8 non-dose-dependent PB-reducing hits. Approximately 70% of the hits appear to act through reducing glycogen synthase (GS) activity, which can elongate glycogen chains and presumably promote PB generation. Some of these GS inhibiting hits were also computationally predicted to be similar to drugs interacting with the GS activator protein phosphatase 1. Our work paves the way to discovering medications for the treatment of PB-involving GSD, which are extremely severe or fatal disorders.

Modificación del Almidón de maiz y sus efectos en el tratamiento de niños con glucogenosis / Modification of starch corn and its effects on the treatment of children with glycogenosis

Introducción: El almidón de maíz (AM) está indicado en el manejo de niños con glucogenosis hepática (GH).Objetivo: Describir la respuesta clínica en siete niños con GH I y III, del Hospital Pablo Tobón Uribe de Medellín, Colombia, al cambiar el AM de uso alimenticio (UA), por AM de pureza farmacológica (PF). Metodología: Estudio observacional, retrospectivo, descriptivo realizado en 51 meses en el que se comparan pruebas bioquímicas y evolución clínica de siete niños ambulatorios con GH, quienes recibían AMUA y se les cambió a AMPF, por recaída en sus controles bioquímicos, relacionados con el cambio en la composición del AM tradicional, al que se le adicionó una mezcla de vitaminas y minerales. Resultados: Se incluyeron 3 niñas y 4 niños entre 13 y 148 meses, 3 con GH I y 4 con GH III, que recibían AMUA, y luego de cambiar a AMPF, presentaron mejoría clínica y bioquímica así: glucemia en ayunas de 77 mg/dL (48-90) a 85 (68-119) mg/dL, ALT de 390 U/L (47-1410) a 159 (47-345) U/L y triglicéridos de 487 (186-1797) mg/dL a 240 (112-614) mg/dL.Conclusiones: El AMPF en niños con GH I y III, demostró resultados mejores, que los obtenidos con el AMUA. La evidencia bioquímica y clínica, permite recomendar su utilización en el tratamiento actual de los pacientes con estos tipos de GH.

Introduction: Corn starch (CS) is indicated for the management of children with liver glucogenosis (LG). Objective: To describe the clinic outcome in 7 children with LG I and III, from Hospital Pablo Tobón Uribe from Medellín, Colombia, to change food (F) CS by the pharmacological purity (PP) CS. Methods: Observational, retrospective, descriptive study performed in 51 months comparing biochemical and clinical course of 7 children outpatient with LG, those receiving FCS and were switched to PPCS by relapse in biochemical controls related to the change in the composition of the traditional commercial CS, which was added a mixture of vitamins and minerals. Results: Were included 3 girls and 4 boys between 13 and 148 months, 3 with LG I and 4 with LG III, receiving FCS, and after switching to PPCS, they improved the biochemical tests and clinical status. Conclusions: PPCS in children with LG I and III, showed better results than those obtained with FCS. The biochemical and clinical evidence both to recommend its use in the current treatment of patients with these types of LG.

Fanconi-Bickel syndrome in a 3-year-old Indian boy with a novel mutation in the GLUT2 gene.

Fanconi-Bickel syndrome is a rare autosomal recessive disorder characterized by hepatorenal glycogen accumulation, proximal renal tubular dysfunction and impaired utilization of glucose and galactose. Most cases have been reported from Europe, Japan, Turkey and the Mediterranean belt. We report a 3-year-old boy from southern India who presented with doll-like facies, florid rickets, massive hepatomegaly, growth retardation, renomegaly and laboratory evidence of proximal renal tubular dysfunction. Liver biopsy demonstrated evidence of glycogenosis. Direct sequencing of genomic DNA confirmed a diagnosis of Fanconi-Bickel syndrome, revealing a G-to-A substitution at position -1 of the splicing acceptor site in intron 1 of the GLUT2 gene in a homozygous pattern (c.16-1G>A or IVS1-1G>A). This novel mutation has not been described in earlier studies. The child was treated with oral potassium citrate, oral phosphorus supplementation, and alpha-calcitriol, on which metabolic derangements were corrected.

Fanconi-Bickel syndrome.

We present here the first case of Fanconi-Bickel syndrome, a rare type of glycogen storage disease, from India. A 17-month-old female child presented with severe growth retardation and abdominal distention. Clinical examination revealed a "doll-like" face, massive hepatomegaly, and rickets. Laboratory investigations confirmed severe hypophosphatemic rickets and proximal renal tubular dysfunction. Liver biopsy showed glycogen accumulation in the hepatocytes.

No mutation in the SLC2A2 ( GLUT2) gene in a Turkish infant with Fanconi-Bickel syndrome.

Fanconi-Bickel syndrome (FBS), or glycogen storage disease type XI, is a rare, well-defined clinical entity. Recently, this disease was elucidated to link mutations in the SLC2A2 gene in many ethnic groups, indicating that FBS is a single gene disease. We report here an 8-month-old Turkish girl who developed characteristic findings of FBS. However, no mutation was detected in the protein-coding region of the SLC2A2 gene. Therefore, we propose that further molecular analysis is needed to determine whether other genes are involved in FBS.

Glicogenosis hepáticas: diagnóstico clínico y manejo nutricional / Glycogen storage disease: clinical diagnosis and nutritional management

Las glicogenosis hepáticas son errores congénitos del metabolismo, secundarios a deficiencia en alguna de las vías de la síntesis o degradación del glicógeno. Objetivo: evaluar los hallazgos clínicos, de laboratorio e histopatológicos de 6 pacientes diagnosticados entre los 13 y los 52 meses de edad con glicogenosis tipo III, IV y IX y describir los resultados iniciales de la terapia nutricional. Cinco niños fueron referidos para evaluación de hepatomegalia masiva, y uno, por presentar una convulsión asociada a hipoglicemia. El diagnóstico fue confirmado mediante una prueba de carga de glucosa oral, en la que todos presentaron una hiperlactacidemia postprandial, una biopsia hepática que confirmó la acumulación intracelular de glicógeno y en tres niños mediante análisis enzimático. Todos tenían elevación de enzimas hepáticas e hiperlipidemia al momento del diagnóstico. Se inició un tratamiento nutricional que, después de al menos 6 meses, resultó en una mejoría del perfil lipídico, con reducción de los niveles de colesterol total en 19 por ciento y elevación del colesterol HDL en 55 por ciento con respecto a los valores iniciales. Conclusiones: las glicogenosis hepáticas deben considerarse dentro del diagnóstico diferencial en niños con hepatomegalia crónica, aparentemente asintomática, sobre todo en presencia de hiperlipidemia. El uso adecuado de exámenes de laboratorio relativamente simples como la prueba de carga de glucosa permitió confirmar la sospecha de estas condiciones y reducir el uso de exámenes invasores, y la dieta permitió una disminución significativa del colesterol total y HDL

Phosphorus NMR spectroscopy study of muscular enzyme deficiencies involving glycogenolysis and glycolysis.

We used phosphorus NMR spectroscopy to study 16 patients with muscular enzyme deficiencies affecting glycogenolysis and glycolysis. Study of phosphomonoester (Pm) kinetics and intracellular pH during exercise and recovery provided criteria for the distinction of these metabolic myopathies by NMR spectroscopy. The Pm peak was undetectable in patients lacking debrancher enzyme or phosphorylase. By contrast, in phosphofructokinase (PFK) or phosphoglycerate kinase (PGK) deficiency, the Pm peak was larger than that of inorganic phosphate in exercise, whereas it was always smaller in normal subjects. During recovery, the disappearance of Pm was slower in PGK than in PFK deficiency.