Abstract: 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.

Resumen: Las enfermedades por depósito de glucógeno (EDG) son un grupo de patologías de baja frecuencia, derivadas de la alteración del metabolismo del glucógeno, lo que lleva a que este se almacene en diferentes órganos como el músculo, riñón e hígado, produciendo distintas manifestaciones clínicas. Las EDG de compromiso hepático se clasifican en los tipos I, III, IV, VI y IX, dependiendo de las distintas enzimas afectadas. Se caracterizan clínicamente por hipoglicemia y hepatomegalia como síntomas cardinales. La sospecha diagnóstica se basa en las manifestaciones clínicas presentes y los resultados de los exámenes de laboratorio, pero el diagnóstico definitivo requiere un estudio genético que identifique la mutación subyacente. Se han descrito múltiples mutaciones para cada EDG. En la población chilena, se desconoce la caracterización genotípica de estas enfermedades. El tratamiento es dietético y se modula según la mutación presente. Hoy día hay amplio consenso en que un buen control metabólico permite mejorar la calidad de vida y el pronóstico de los pacientes. En esta revi sión se actualiza la información sobre las EDG que presentan compromiso hepático, para optimizar el diagnóstico, tratamiento y seguimiento de estos pacientes, dando énfasis al manejo específico nu tricional y gastroenterológico.

Abstract Introduction: Glutaric Aciduria Type 1 (GA-1) is produced by the enzymatic deficiency of glutaryl-CoA-dehydrogenase (GCDH), leading to the accumulation of glutaric acid (GA). 90% of patients without early treatment present acute encephalopathic crisis (AEC), followed by disabling neurological symptoms. The treatment consists of a low lysine (Lys) diet, protein substitute lys-free, tryptophan-reduced (PS) and L-carnitine. Objectives: Describe the clinical and nutritional evolution of a cohort of GA-1 patients at a national referral center in Chile. Methodology: Retrospective study of 24 patients diagnosed with GA-1 between 1998-2020 and referred to the Institute of Nutrition and Food Technology (INTA) of University of Chile. Results: Age at diagnosis was 19±27 months; 10/24 presented AEC and neurological sequelae. The cases without AEC (14/24) 8 presented neurological compromise: psychomotor development delay, abnormal movements and pyramidal syndrome. Nutritional evaluation: 12/24 were malnourished by deficiency, <6 years old group (12/24): 11 cases were found to have Lys and PS, ≥6 years old (12/24): 9/12 did not receive PS. All had normal free carnitine levels. Conclusion: GA-1 has variable symptoms with neurological involvement AEC or insidious start. Is essential to maintain a long-term follow-up and consider its inclusion in neonatal screening programs.

Hyperphenylalaninaemias are defined by a blood phenylalanine over 2 mg/dl. The main cause is due to a mutation in the gene that codes the phenylalanine hydroxylase that catalyses the reaction that converts phenylalanine into tyrosine. The hyperphenylalaninaemias are classified into benign or mild hyperphenylalaninaemias, or mild, moderate or classic phenylketonurias. Due to its delayed detection outside the neonatal period it causes severe mental retardation. Its detection along with congenital hypothyroidism has been part of the National Neonatal Screening Program since 1992 in Chile. This article aims to answer the most common questions asked by the paediatrician when faced with a patient with hyperphenylalaninaemias.

Las hiperfenilalaninemias se definen por un nivel sanguíneo de fenilalanina sobre 2 mg/dl. La principal causa es una mutación en el gen que codifica la fenilalanina hidroxilasa que cataliza la reacción que transforma la fenilalanina en tirosina. Las hiperfenilalaninemias se clasifican en benignas o leves, y las fenilcetonurias en leves, moderadas y clásicas. Debido a que su detección más allá del periodo neonatal causa retardo mental severo, desde 1992 en Chile su detección, junto con la del hipotirodismo congénito, es parte del Programa Nacional de Pesquisa Neonatal. Este artículo pretende responder las preguntas más comunes que se puede hacer el pediatra cuando enfrenta a un paciente con hiperfenilalaninemias.

This review aims to provide clinicians in Latin America with the most current information on the clinical aspects, diagnosis, and management of Hunter syndrome, a serious and progressive disease for which specific treatment is available. Hunter syndrome is a genetic disorder where iduronate-2-sulfatase (I2S), an enzyme that degrades glycosaminoglycans, is absent or deficient. Clinical manifestations vary widely in severity and involve multiple organs and tissues. An attenuated and a severe phenotype are recognized depending on the degree of cognitive impairment. Early diagnosis is vital for disease management. Clinical signs common to children with Hunter syndrome include inguinal hernia, frequent ear and respiratory infections, facial dysmorphisms, macrocephaly, bone dysplasia, short stature, sleep apnea, and behavior problems. Diagnosis is based on screening urinary glycosaminoglycans and confirmation by measuring I2S activity and analyzing I2S gene mutations. Idursulfase (recombinant I2S) (Elaprase®, Shire) enzyme replacement therapy (ERT), designed to address the underlying enzyme deficiency, is approved treatment and improves walking capacity and respiratory function, and reduces spleen and liver size and urinary glycosaminoglycan levels. Additional measures, responding to the multi-organ manifestations, such as abdominal/inguinal hernia repair, carpal tunnel surgery, and cardiac valve replacement, should also be considered. Investigational treatment options such as intrathecal ERT are active areas of research, and bone marrow transplantation is in clinical practice. Communication among care providers, social workers, patients and families is essential to inform and guide their decisions, establish realistic expectations, and assess patients' responses.

Gaucher disease -due to its low frequency- is considered an orphan disease. In 1991 the International Gaucher Registry was created and in 1992 the first patients from Latin America were enrolled. In 2008 the Latin American Group for Gaucher Disease was initiated. Its main objectives are to promote regional consensus, to stimulate the enrolment of patients into the International Gaucher Registry and the enhancement of knowledge on this disease, and to achieve better care and quality of life of patients in our Region. Until April 2010, 5828 patients have been enrolled all around the world, 911 (15.6%) from Latin America. This is the first comprehensive report of the disease in the Region. In our population there is a predominance of females, the most common clinical form is the type I (95%) and the age at diagnosis is before 20 years in 68% of patients. The most frequent clinical manifestations at diagnosis are splenomegaly (96%) and anemia (49%). Eighty percent of patients had radiographic findings of bone involvement. In our Region, the vast majority of patients (89%) had received enzyme replacement therapy with imiglucerase; with a long follow-up (up to 10 years) they have achieved the therapeutic goals, showing the great effectiveness of therapy. While the percentage of patients with therapy is high, discontinuations are common. The main deficiencies in our Region are: the lack of visceral volumetric evaluations and densitometries as well as molecular analysis for some patients. The main problem is the under-diagnosis of patients.

La enfermedad de Gaucher, por su escasa frecuencia, está incluida dentro de las llamadas enfermedades huérfanas. En 1991 se creó el Registro Internacional de Gaucher y en 1992 se incorporaron los primeros pacientes de Latinoamérica. En el año 2008 se creó el Grupo Latinoamericano para la Enfermedad de Gaucher (GLAEG) cuyos principales objetivos son fomentar la realización de consensos regionales, difundir el ingreso de pacientes al registro internacional y aumentar el conocimiento sobre la enfermedad para lograr mejorar la atención y la calidad de vida de los pacientes. Hasta abril del 2010 ingresaron 5828 pacientes de todo el mundo, 911 (15.6%) son de Latinoamérica. Este es el primer informe global de la enfermedad en la Región: hay un predominio del sexo femenino, la forma clínica más frecuente es el tipo I (95%); al diagnóstico la mayoría son <20 años (68%). Las manifestaciones clínicas más frecuentes al diagnóstico son esplenomegalia (96%) y anemia (49%), el 80% presentó hallazgos radiológicos de compromiso óseo. En nuestra Región, la gran mayoría de los pacientes (89%) ha recibido alguna vez terapia de reemplazo enzimática con imiglucerasa logrando, con un seguimiento prolongado (hasta10 años), las metas terapéuticas que muestran la gran eficacia de la terapia. Si bien el porcentaje de pacientes con terapia es alto, las suspensiones de tratamiento son frecuentes. Las principales deficiencias en nuestra Región son: la carencia de evaluaciones viscerales volumétricas, de densitometría y de estudios moleculares en algunos pacientes. El principal problema es el subdiagnóstico.

Background: Tyrosinemia type I is an inborn error of metabolism due to deficiency of fumarilacetoacetase. Acute presentation is with liver failure, hypophosphatemic rickets and peripheral neuropathy. Chronic presentation is with visceromegaly and subclinical rickets. The most severe complications are hepatic cancer and acute neurological crises. Without treatment, tyrosinemia type 1 is fatal. In 1992 treatment for tyrosinemia type 1 with 2-(2-nitro-4-trifluoromethybenzoyl)-1,3-ciclohexanedione (NTBC) was proposed. A clinical response was reported in 90% of patients. In cases that did not respond, a successful liver transplantation was performed, reducing mortality to 5%. Aim: To report the follow up of 12 patients treated with NTBC. Patients and Methods: Review of clinical records of 12 Chilean cases treated with NTBC at the Instituto de Nutrición y Tecnología de los Alimentos (INTA) from January 2004 until June 2010. Results: In all patients, a rapid metabolic control was achieved. Two patients developed hepatocarcinoma. One of these patients died and one was successfully treated with liver transplantation. One patient died after receiving a liver transplantation. Nine patients have at present good liver function, but 2 had peripheral neuropathy due to late diagnosis and discontinuing NTBC treatment. Conclusions: Treatment with NTBC allows metabolic normalization in tyrosinemia type 1, prevents liver cirrhosis and hepatic cancer, improving survival rates and quality of life in the patients. Neonatal screening is essential for the early diagnosis of this treatable disease, that otherwise may be lethal.

La Fenilquetonuria (PKU) se produce por un defecto total o parcial de la enzima fenilalanina hidroxilasa (FAH) acumulándose fenilalanina (FA) en sangre, lo que ocasiona retardo mental si no es diagnosticada en el período de recién nacido. El tratamiento consiste en una dieta restringida en FA. Diversos estudios han señalado que debido a la restricción de proteínas animales, la dieta es deficiente en ácidos grasos: alfalinolénico (ALL) y elevada en ácidos linoléico (AL). El objetivo de este estudio fue determinar la ingesta de lípidos en niños PKU diagnosticados precozmente, estudiándose la composición química de lípidos de la dieta de 29 niños con PKU, en dieta restringida en FA y en seguimiento en el INTA, Universidad de Chile. Fueron pareados por sexo y edad con un grupo control. Se aplicó encuesta de recordatorio de 24 horas por tres días consecutivos, calculándose la ingesta de ácidos grasos totales, saturados, monoinsaturados, poliinsaturados, AL y ALL. Los resultados muestran que la dieta de los PKU aporta el 31.8% como calorías grasas, de los cuales el 13% es AL y un 0.2% ALL, existiendo diferencias significativas con respecto al grupo control. La relación obtenida entre ácidos grasos saturados-monoinsaturados-poliinsaturados fue de 1:1.7:3.9 y la razón entre AL y ALL fue diez veces más de lo recomendado (115:1). Concluyéndose que la dieta de los niños PKU chilenos contiene mayor cantidad de AL y menor de ALL.

Phenylketonuria (PKU) is a genetic disorder caused by a partial or complete mutation of the enzyme phenylalanine hydroxylase (PHA), fact that produces high levels of phenylalanine in blood resulting in mental retardation if not diagnosed during the neonatal period. Treatment consists of a phenylalanine (Phe) restricted diet. Several studies have shown that due to restriction of animal protein, this diet is deficient in fatty acids such as alfalinolenic acid (ALA) and provides high levels of linoleic acid (LA). The objective of this study was to determine the lipid composition of the diet consumed by children with early-diagnosed PKU. Lipid composition of the Phenylalanine restricted diet consumed by 29 children with PKU and in follow-up at INTA, University of Chile, were analyzed. Children were paired by sex and age with a control group. A twenty-four hour dietary recall was performed for 3 consecutive days and total fatty acid intake, including saturated, monounsaturated, polyunsaturated, LA and ALA, were calculated. In the restricted diet of children with PKU, 31.8% of total calories are from fat, 13% of which are LA and 0.2% ALA, showing significant differences as compared to the control group. The ratio of saturated: monounsaturated: polyunsaturated fatty acids was 1:1.7:3.9 and the ratio of LA: ALA was ten-fold higher than the recommended ratio of 115:1. It is concluded that the Phenyalanine restricted diet of Chilean children with PKU is high in LA and low in ALA.