Diálisis peritoneal en un neonato con enfermedad de la orina con olor a jarabe de arce. A propósito de un caso / Peritoneal dialysis in a neonate with maple syrup urine disease. A case report

La enfermedad de jarabe de arce es una entidad autosómica recesiva producida por un error congénito en el metabolismo de tres aminoácidos esenciales de cadena ramificada: valina, leucina e isoleucina. La forma neonatal de esta enfermedad se manifiesta por un cuadro de compromiso neurológico grave y progresivo, asociado a un olor peculiar de la orina, consecuencia de la eliminación del exceso de estos aminoácidos. Este olor a azúcar quemada remeda a la melaza obtenida de los arces, lo que da nombre a esta enfermedad. El mejor método para eliminar estos tóxicos es la hemodiafiltración, pero, en los centros en los que esta práctica no es posible, la diálisis peritoneal constituye una alternativa.Se presenta a un recién nacido con leucinosis, con compromiso grave del sistema nervioso central, en quien la diálisis peritoneal fue de utilidad para superar la descompensación metabólica.

Maple syrup disease is an autosomal recessive entity caused by a congenital error in the metabolism of three essential branched-chain amino acids: valine, leucine and isoleucine. The neonatal form of this disease is expressed by a severe and progressive neurological compromise, associated with a peculiar smell of urine, a consequence of the elimination of the excess of these amino acids. This smell of burnt sugar mimics the molasses obtained from maples, which gives its name to this disease. The best method to eliminate these toxins is hemodiafiltration, but in centers where this practice is not possible, peritoneal dialysis is an alternative.We present a newborn with leukinosis with severe central nervous system involvement in whom peritoneal dialysis was useful to overcome metabolic decompensation.

Gaps in the newborn screening process: Using maple syrup urine disease as a case

@#Saving babies from mental retardation and death is the aim of the newborn screening program. A complex process of sample collection, processing and feedback is undertaken before reaching this goal. As with other systems, the newborn screening program is not perfect and periodic review is needed to continually improve services. Using maple syrup urine disease (which is the most common inborn error of metabolism detected through newborn screening) as an index case, this paper aims to present the gaps in diagnosis and management by citing cases and providing a commentary.

Clinical and genetic analysis of a case of dihydrolipoamide dehydrogenase deficiency caused by novel variant of DLD gene / 中华医学遗传学杂志

OBJECTIVE@#To analyze the clinical and genetic characteristics of a patient with dihydrolipoamide dehydrogenase deficiency.@*METHODS@#Potential variants of the DLD gene were detected by whole exome sequencing and verified by Sanger sequencing.@*RESULTS@#Compound heterozygous variants, c.704_705delTT (p.Leu235Argfs*8) and c.1058T>C (p.Ile353Thr), were detected in the DLD gene. The c.1058T>C (p.Ile353Thr) variant was derived from his mother and known to be pathogenic. The c.704_705delTT (p.Leu235Argfs*8) variant was derived from his father and was unreported previously.@*CONCLUSION@#The compound heterozygous variants of c.704_705delTT (p.Leu235Argfs*8) and c.1058T>C (p.Ile353Thr) of the DLD gene probably underlay the disease in this patient. Above finding has facilitated genetic counseling and prenatal diagnosis for the family.

Clinical profiles and outcomes of the most common inherited metabolic diseases in the Philippines: A review of the National Institutes of Health - Institute of Human Genetics Metabolic Registry

@#<p><strong>OBJECTIVE:</strong> This study reviewed the profiles and outcomes of patients diagnosed to have the five most common inherited metabolic diseases (IMDs) in the Metabolic Registry of the National Institutes of Health - Institute of Human Genetics (NIH-IHG) from 1999 to 2016.</p><p><br /><strong>METHODS: </strong>The medical records of the patients diagnosed with the following inherited metabolic diseases were reviewed: maple syrup urine disease (MSUD), galactosemia, hyperphenylalaninemias (including classical phenylketonuria, mild hyperphenylalaninemia, and pterin defects), mucopolysaccharidoses (MPS), and adrenoleukodystrophy (ALD).</p><p><br /><strong>RESULTS:</strong> There was a total of 567 patients with IMDs, giving a minimum estimated burden of 1.9 per 100,000 livebirths (1:51,760). Clinical presentations were similar to those reported in literature. Majority of the cases of galactosemia and hyperphenylalaninemias presented with a positive newborn screening result. The local prevalence of MSUD and MPS II were higher compared to international data, which may be explained by reported founder mutations among Filipinos. Majority of the patients with IMDs were diagnosed late leading to preventable developmental delay or intellectual disability and death. Majority of patients with MSUD (80.6%) and MPS (94.7%) had intellectual disability or developmental delay. Mortality was 50.5% among patients with MSUD and 100% among patients with adrenoleukodystrophy.</p><p><br /><strong>CONCLUSION: </strong>There is a diversity of IMDs present in the country. A long-term strategic plan, such as the full implementation of the National Rare Disease Act, is foreseen to improve access to comprehensive healthcare and quality of life of patients with IMDs in the country.</p>

Progress of research on Maple syrup disease / 中华医学遗传学杂志

Maple syrup disease (MSUD) is a rare autosomal recessive disorder caused primarily by mutations of branched-chain keto acid dehydrogenase complex (BCKDC). BCKDC includes at least four pathogenic genes of BCKDHA, BCKDHB, DLD and DBT. The clinical manifestations of MSUD are complex, and the main symptoms at the early stage include difficulty in feeding, drowsiness, change in muscle tone and special urine flavor of maple syrup. As the disease progresses, convulsion, hypoglycemia, coma and systemic failure may occur. MSUD is easily missed or misdiagnosed during the neonatal period. This paper provides a review for recent progress made in research on MSUD including etiology, physiopathology, clinical manifestation, auxiliary examination and treatment, with a particular emphasis on genetic testing and treatment.

Report on the External Quality Assessment Scheme for Metabolite Testing in Korea (2016–2017)

External quality assessment (EQA) trials of conventional newborn screening tests for phenylketonuria, galactosemia, congenital adrenal hyperplasia, maple syrup urine disease, homocystinuria, and congenital hypothyroidism, as well as extended newborn screening tests using tandem mass spectrometry, were performed twice in 2016 and 2017. A total of 44 specimens in the form of dried blood spots were distributed in each trial to 16 laboratories. The response rate of these laboratories was 100%. The mean, standard deviation, coefficient of variation, median, and cut-offs were evaluated for each analyte in the newborn screening tests. EQA trials for the analyses of methylmalonic acid, vanillylmandelic acid, catecholamines, metanephrines, organic acids, and amino acids were also performed. A well-designed EQA program and continuous education would improve the performance of metabolite testing.

Enfermedad de la orina de jarabe de arce: trastornos metabólicos y limitaciones en Honduras / Maple Syrup Urine Disease: Metabolic Disorders and Limitations in Honduras

Antecedentes: La Enfermedad de la Orina con olor a Jarabe de Arce es un error innato del metabolismo causada por deficiencia de actividad de la deshidrogenasa de los cetoácidos, que lleva acumular aminoácidos de cadena ramificada que produce una encefalopatía neonatal y al no ser tratada tempranamente, deja secuelas neurológicas permanentes hasta la muerte. Caso Clínico: Recién nacida producto de parto eutocico, a término, respiración espontanea, llanto vigoroso y buen tono muscular, alimentación exclusiva con lactancia materna. Antecedentes maternos de 2 hijos muertos en período neonatal. Paciente se presenta a los 7 días con pobre succión, vómitos, hipoactividad y fiebre. Examen físico: hipoactivo, reflejo de moro incompleto, llanto débil y constante. Posteriormente movimientos en extremidades superiores que simulan "boxeo" e hipertonicos, y pedaleo en extremidades inferiores, fontanela tensa y abombada, respiración irregular y bradipnea, se realiza intubación endotraqueal, ventilación mecánica y manejo en UCIN, EEG actividad eléctrica convulsiva, TAC cerebral normal. Se investiga enfermedad metabólica y se solicita tamizaje neonatal . Se inicia tiamina/levocarnitina ante sospecha de un error innato del metabolismo. A los 23 días de vida los resultados revelan niveles elevados de los aminoácidos específicos de la MSUD. Discusión: MSUD es una entidad rara en el mundo, que cursa con secuelas neurológicas permanentes y muerte de no ser tratada. Honduras no realiza métodos de Tamizaje Neonatal, es importante que el médico sospeche de manera temprana estas enfermedades, realizar un diagnóstico oportuno, se conduzca un tratamiento multidisciplinario y exista una mayor accesibilidad a las fórmulas especializadas..(AU)

A 1-year-old female with maple syrup urine disease presenting with acrodermatitis-enteropathica-like lesions

@#<p>A 1-year-old female with maple syrup urine disease presenting with erythematous, partially eroded plaques on the trunk, anogenital area, and extremities experienced metabolic crisis. The skin lesions appeared at 11 months of age and was thought to result from amino acid imbalance secondary to erratic supplementation of specialized milk formula devoid of isoleucine, leucine, and valine. Serial urine monitoring showed persistent ketones and elevated serum leucine and valine. The patient was managed with emollients, intralipid 20%, and addition of isoleucine and valine supplements to counter the neurotoxic effect of leucine. After 8 days of proper feeding and continuous emollient application, the lesions improved and skin biopsy revealed superficial perivascular dermatitis. Although a decrease in erythema and desquamation was noted, the patient had persistent cerebral edema and continued to deteriorate.</p>

Enfermedad de orina con olor a jarabe de arce: reporte de dos casos / Maple urine disease: two case reports

Introducción: La enfermedad de orina con olor a jarabe de arce (EOJA) es un trastorno del metabolismo de los aminoácidos de cadena ramificada (ACR). Tiene una incidencia de 1 en 85.000­185.000 recién nacidos (RN) vivos, siendo mayor en poblaciones con alta tasa de consanguineidad. Se debe al déficit del complejo enzimático BCKDC (Branched-chain alpha-keto acid dehydrogenase complex). Objetivo: Sensibilizar respecto al diagnóstico precoz, describiendo la presentación y evolución clínica de 2 casos presentados en menos de un año. Presentación del caso: Caso 1: Recién nacido de término (RNT), sin antecedentes mórbidos personales ni familiares, consulta al 11er día de vida (DDV) por cuadro de irritabilidad, rechazo alimentario, mirada fija e hipertonía. Hospitalizado por 55 días con progresiva mejoría neurológica. Al alta solo leve retraso del desarrollo psicomotor (RDSM). Caso 2: RNT, sin antecedentes mórbidos personales ni familiares, consultó al 12° DDV por cuadro de hipoactividad y rechazo alimentario. Hospitalizado por 70 días con evolución clínica y neurológica dificultosa. Al alta con trastorno deglutorio que requirió gastrostomía. En ambos casos se planteó sospecha de EOJA por aminoacidemia y aminoaciduria característica, confirmándose por medición cuantitativa de aminoácidos. Discusión: Existen cinco fenotipos diferentes, clasificados principalmente por presentación clínica y edad de debut, siendo el más frecuente la forma clásica (ambos casos). Resulta muy importante el diagnóstico precoz y manejo por su relación con el pronóstico neurológico, sin embargo, en Chile no se cuenta actualmente con un screening neonatal universal. El tratamiento se basa en un manejo nutricional estricto y la corrección de desequilibrios metabólicos e hidroelectrolíticos, ambos frecuentes en esta condición.

Introduction: The maple syrup urine disease (MSUD) is a metabolic disorder of branchedchain amino acids. It has an incidence of 1/85000 ­ 185000 live newborns being higher in in populations with a high rate of consanguinity. It is due to deficit BKDC enzyme complex (Branched-chain alpha-keto acid dehydrogenase complex). Objective: To raise awareness to early diagnosis, describing the presentation and clinical course of 2 cases presented in less than one year. Case report: Case 1: Full-term newborn with no personal or family history of morbidity presented the 11th day of life with irritability, food rejection, fixed stare and hypertonia. He was hospitalized for 55 days with progressive neurological improvement. At discharge only slightly delayed psychomotor development. Case 2: Full-term newborn with no personal or family history of morbidity presented the 12th day of life with hipoactivity and food rejection. He was hospitalized for 70 days with difficult clinical and neurological outcome. The patient was discharged with swallowing disorder that required gastrostomy. In both cases MSUP suspicion arises by aminoacidemia and aminoaciduria and confirmed by quantitative measurement of amino acids. Discussion: There are 5 different phenotypes classified chiefly by clinical presentation and age, being most frequent the classical form. It is very important to do an early diagnosis and management for its impact on neurological outcome; however, Chile does not currently has an universal neonatal screening. The treatment is based on a strict nutritional management and correction of metabolic and electrolyte imbalances, both common in this condition.

Maple syrup urine disease and gene mutations in twin neonates / 中国当代儿科杂志

<p><b>OBJECTIVE</b>To investigate the clinical features of one pair of twin neonates with maple syrup urine disease (MSUD) in the Chinese Han population and pathogenic mutations in related genes, and to provide guidance for the early diagnosis and treatment of MSUD.</p><p><b>METHODS</b>The clinical and imaging data of the twin neonates were collected. The peripheral blood samples were collected from the twin neonates and their parents to detect the genes related to MSUD (BCKDHA, BCKDHB, DBT, and DLD). The loci with gene mutations were identified, and a bioinformatic analysis was performed.</p><p><b>RESULTS</b>Two mutations were detected in the BCKDHB gene, missense mutation c.304G>A (p.Gly102Arg) and nonsense mutation c.331C>T (p.Arg111*), and both of them were heterozygotes. The mutation c.304G>A (p.Gly102Arg) had not been reported in the world. Their father carried the missense mutation c.304G>A (p.Gly102Arg), and their mother carried the nonsense mutation c.331C>T (p.Arg111*).</p><p><b>CONCLUSIONS</b>The c.331C>T (p.Arg111*) heterozygous mutation in BCKDHB gene is the pathogenic mutation in these twin neonates and provides a genetic and molecular basis for the clinical features of children with MSUD.</p>

Annual Report on the External Quality Assessment Scheme for Biochemical Genetics in Korea (2015)

Two external quality assessment (EQA) trials of conventional newborn screening tests for phenylketonuria, galactosemia, congenital adrenal hyperplasia, maple syrup urine disease, homocystinuria, and congenital hypothyroidism, as well as newborn screening tests using tandem mass spectrometry, were performed in 2015. A total of 44 specimens in the form of dried blood spots were distributed to 16 laboratories and the response rate of these laboratories was 100%. The mean, standard deviation, coefficient of variation, median, and cut-offs were evaluated for each analyte in the newborn screening tests. Two EQA trials for the analyses of methylmalonic acid, vanillylmandelic acid, catecholamines, metanephrines, organic acids, and amino acids were also performed. A well-designed EQA program and continuous education would improve the performance of biochemical genetics tests.

Enfermedad de orina a jarabe de arce: presentación de caso clínico / Maple Syrup Urine Disease: A case report

Antecedentes: La enfermedad de orina olor a jarabe de arce (EOJA) es un error congénito del metabolismo de herencia autosómica recesiva, causado por la actividad defectuosa del com- plejo enzimático deshidrogenasa de α -cetoáci- dos, ocasionando que los aminoácidos de cadena ramificada; valina, leucina e isoleucina no puedan catabolizarse completamente. Se trata de lactante menor, tres meses de edad, con antecedente de vómitos frecuentes y rechazo a la alimentación desde la primera semana de vida, tratado por alergia a la proteí- na de la leche de vaca y reflujo gastroesofágico grado IV, con varios cambios de formula en su alimentación. Trasladado al Instituto Hondure- ño del Seguro Social, Hospital Regional del Norte (IHSS-HRN) con historia de cinco días de tos, fiebre y aproximadamente nueve horas de dificultad respiratoria. Tres horas más tarde presenta convulsiones tónicas y choque, por lo que se trasladado a sala de cuidados intensivos pediátricos, acoplándose a ventilador mecáni- co. Laboratorialmente: acidosis metabólica persistente que se logró controlar a las 48 horas, Anión Gap: 17, cetonuria, IRM con impor- tante atrofia cortical. Se encontró elevación de los metabolitos de aminoácidos de cadena ramificada; 2-OH isovalerico, 2- OH isocaproico, 2-ceto-3 methylvalerico, 2 cetoisocaproico consistentes con EOJA y elevación del ácido láctico y alfa cetoglutarato; que podrían indicar defectos en la subunidad E3 de la enzima deshidrogenasa. Conclusiones: Los errores innatos del metabolismo son más frecuente- mente diagnosticados cada día, y deben sospe- charse en los niños con vómitos frecuentes...(AU)

Maple syrup urine disease in Brazil: a panorama of the last two decades / Doença da urina de xarope de bordo no Brasil: um panorama das últimas duas décadas

OBJECTIVE: To characterize a sample of Brazilian patients with maple syrup urine disease (MSUD) diagnosed between 1992 and 2011. METHODS: In this retrospective study, patients were identified through a national reference laboratory for the diagnosis of MSUD and through contact with other medical genetics services across Brazil. Data were collected by means of a chart review. RESULTS: Eighty-three patients from 75 families were enrolled in the study (median age, 3 years; interquartile range [IQR], 0.57-7). Median age at onset of symptoms was 10 days (IQR 5-30), whereas median age at diagnosis was 60 days (IQR 29-240, p = 0.001). Only three (3.6%) patients were diagnosed before the onset of clinical manifestations. A comparison between patients with (n = 12) and without (n = 71) an early diagnosis shows that early diagnosis is associated with the presence of positive family history and decreased prevalence of clinical manifestations at the time of diagnosis, but not with a better outcome. Overall, 98.8% of patients have some psychomotor or neurodevelopmental delay. CONCLUSION: In Brazil, patients with MSUD are usually diagnosed late and exhibit neurological involvement and poor survival even with early diagnosis. We suggest that specific public policies for diagnosis and treatment of MSUD should be developed and implemented in the country. .

OBJETIVO: Caracterizar uma amostra de pacientes brasileiros com a doença da urina de xarope de bordo (DXB) diagnosticados entre 1992 e 2011. MÉTODOS: Os pacientes foram identificados por meio de um laboratório de referência nacional para o diagnóstico de DXB e por meio do contato com outros serviços de genética médica no Brasil. Os dados foram coletados por meio de uma revisão de prontuários. RESULTADOS: Foram incluídos no estudo 83 pacientes de 75 famílias (idade média: três anos; intervalo interquartil (IQR): 0,57-7). A idade média no surgimento dos sintomas era de 10 dias (IQR: 5-30), ao passo que a idade média no diagnóstico era de 60 dias (IQR: 29-240; p = 0,001). Somente três (3,6%) pacientes foram diagnosticados antes do surgimento de manifestações clínicas. Uma comparação entre pacientes com (n = 12) e sem (n = 71) um diagnóstico precoce mostra que o diagnóstico precoce está associado à presença de histórico familiar positivo e à redução na prevalência de manifestações clínicas no momento do diagnóstico, porém sem melhor resultado. Em geral, 98,8% dos pacientes têm algum atraso no desenvolvimento psicomotor ou neurológico. CONCLUSÃO: No Brasil, os pacientes com DXB normalmente recebem um diagnóstico tardio e exibem um envolvimento neurológico e baixa sobrevivência, mesmo com um diagnóstico precoce. Sugerimos que políticas públicas específicas para o diagnóstico e tratamento da DXB sejam desenvolvidas e implementadas no país. .

Maple syrup urine disease caused by two novel BCKDHB gene mutations in a Chinese neonate / 中华儿科杂志

<p><b>OBJECTIVE</b>Maple syrup urine disease (MSUD) is an autosomal recessive metabolic disorder that is caused by mutations in the subunits of the branched chain α-ketoacid dehydrogenase (BCKD) complex. This report presents a Han ethnic Chinese newborn infant with the severe classic form of MSUD caused by two novel missense mutations in the BCKDHB gene.</p><p><b>METHOD</b>The clinical and biochemical data of a Chinese neonate with classic form of MSUD were analyzed, and the DNA sequences of BCKDHA, BCKDHB, DBT and DLD genes were investigated for mutations. Then the DNA samples of the proband and the patient's parents were tested with Sanger sequencing.</p><p><b>RESULT</b>The manifestations of this patient were poor feeding, low reaction, and compensatory metabolic acidosis. Tandem mass spectrometry (MS/MS) showed that leucine and valine were significantly higher than normal. Urine gas chromatography-mass spectrometry (GC/MS) showed significant abnormality. Brain CT scan showed white matter changes. We identified two previously unreported mutations in the BCKDHB gene, p.Leu194Phe (c.580 C>T) and p.Ser199Arg (c.597 T>G) in exon 5. Segregation analysis showed that the novel mutation p.Ser199Arg was maternally inherited and the novel mutation p.Leu194Phe was paternally inherited. Neither mutation was found in the 186 alleles of 93 normal Han ethnic Chinese individuals. In human BCKDHB protein crystal structure, the 194th and 199th amino acids changes are likely to affect the spatial structure of the protein. The 194th and 199th amino acid of human BCKDHB protein was conserved among species. PolyPhen protein function prediction indicated that the 194th and 199th amino acid changes were likely to affect protein function.</p><p><b>CONCLUSION</b>Two novel missense mutations were identified in the BCKDHB gene in the Chinese patient with MSUD.</p>

Annual Report on the External Quality Assessment Scheme for Biochemical Genetics in Korea (2014)

Two trials of external quality assessment (EQA) of conventional newborn screening tests for phenylketonuria, galactosaemia, congenital adrenal hyperplasia, maple syrup urine disease, homocystinuria, and congenital hypothyroidism, as well as newborn screening tests were performed using tandem mass spectrometry in 2014. A total of 39 specimens in the form of dried blood spots were distributed to 16 laboratories and the response rate of these laboratories was 100%. Screening tests for phenylketonuria and congenital hypothyroidism did not meet the accepted performance criteria in some laboratories. The mean, standard deviation, coefficient of variation, median, and cut-offs were evaluated for each analyte in the newborn screening tests. Two trials of EQA for the analyses of methylmalonic acid, vanillylmandelic acid, catecholamines, metanephrines, organic acids, and amino acids were also performed. A well-designed EQA program and continuous education would improve the performance of biochemical genetic testing.

Evaluación del seguimiento de 29 niños chilenos con la enfermedad de la orina olor a jarabe de arce clásica / Follow up evaluation of 29 chilean children with classical maple syrup urine disease

Introduction: Maple Syrup Urine Disease (MSUD) is caused by a defect of the ketoacid dehydrogenase enzyme complex of the branched amino acids Valine, Isoleucine and Leucine (VIL). The treatment consists of a leucine-restricted diet. Objective: To evaluate the long-term follow-up in children with MSUD. Methodology: 29 records were reviewed of patients with MSUD, of which 24 were clinically identified (> 5th day of life), 4 cases by MSUD family history and one by neonatal screening (< 5th day of life). Leucine (Leu) levels were measured at diagnosis (Biotronic 2000) and during follow-up (mass spectrometry). The number of decompensation events, Total Intellectual Quotient (TIQ, Bayley and Wechsler scale) and nutritional status were also measured. STATA statistical software version 9.2 was applied (p≤0.05). Results: Mean age at diagnosis was 14 days old. In all cases the diagnosis was confirmed by elevated levels of Leu and alloisoleucin. When comparing the TIQ of 19 cases over 3 years old with their age at diagnosis, it was observed that those cases screened by the 5th day of life had a TIQ 84.6 ± 13, while those diagnosed later had a TIQ 73 ± 17 (p≤0.05). In assessing the number of hospitalizations that occurred during follow-up, we determined that the 5 cases screened early never had a metabolic crisis and had a higher TIQ than those who had had one or more decompensation (92 and 74, respectively, p≤0.05). An inverse correlation was observed between the Leu+Isoleucine value and TIQ. Conclusion: The diagnosis before the 5th day of life and a good metabolic control during follow-up, enables children with MSUD to have normal cognitive development.

La enfermedad de la orina olor a jarabe de arce (EOJA) se produce por un defecto del complejo enzimático deshidrogenasa de los cetoácidos de los aminoácidos ramificados: Valina, Isoleucina, Leucina (VIL). El tratamiento es una dieta restringida en leucina (Leu). Objetivo: evaluar el seguimiento a largo plazo en niños con EOJA. Metodología: Se revisaron 29 fichas de pacientes EOJA, 24 fueron pesquisados por clínica (> 5to día de vida) y 4 casos por antecedentes familiares con EOJA y 1 por pesquisa neonatal (< 5to día de vida). Se midió nivel de Leu al diagnóstico (Biotronic 2000) y durante el seguimiento (Espectrometría de masa), número de descompensaciones, Coeficiente Intelectual Total (CIT) (Escalas de Bayley y Wechsler) y estado nutricional. Se aplicó programa estadístico STATA versión 9.2 (p≤0.05). Resultados: La edad de diagnóstico fue a los 14 días de edad. En todos se confirmó el diagnóstico por los niveles elevados de Leu y presencia de alloisoleucina. Al comparar el CIT de los 19 casos mayores de 3 años con la edad de diagnóstico, se observó que aquellos casos pesquisados antes del 5to día tenían un CIT de 84,6±13, a diferencia de los diagnosticados posteriormente que tenían un CIT=73±17 (p≤0.05). Al evaluar el número de descompensaciones ocurridas durante el seguimiento, se determinó que los 5 casos nunca habían tenido una crisis metabólica, tuvieron un CI mayor que aquellos que habían tenido una o más descompensaciones (92 y 74 respectivamente) (p≤0.05). Cuando se correlacionó el valor de Leu+Iso de seguimiento con el CIT, se observó una correlación inversamente proporcional. Conclusión: el diagnóstico antes de los 5to día de vida y un buen control metabólico durante el seguimiento, permite que los niños con EOJA tengan un desarrollo cognitivo normal.

Successful domino liver transplantation in maple syrup urine disease using a related living donor

Maple syrup urine disease (MSUD) is an autosomal recessive disease associated with high levels of branched-chain amino acids. Children with MSUD can present severe neurological damage, but liver transplantation (LT) allows the patient to resume a normal diet and avoid further neurological damage. The use of living related donors has been controversial because parents are obligatory heterozygotes. We report a case of a 2-year-old child with MSUD who underwent a living donor LT. The donor was the patient's mother, and his liver was then used as a domino graft. The postoperative course was uneventful in all three subjects. DNA analysis performed after the transplantation (sequencing of the coding regions of BCKDHA, BCKDHB, and DBT genes) showed that the MSUD patient was heterozygous for a pathogenic mutation in the BCKDHB gene. This mutation was not found in his mother, who is an obligatory carrier for MSUD according to the family history and, as expected, presented both normal clinical phenotype and levels of branched-chain amino acids. In conclusion, our data suggest that the use of a related donor in LT for MSUD was effective, and the liver of the MSUD patient was successfully used in domino transplantation. Routine donor genotyping may not be feasible, because the test is not widely available, and, most importantly, the disease is associated with both the presence of allelic and locus heterogeneity. Further studies with this population of patients are required to expand the use of related donors in MSUD.

Identification of Two Novel BCKDHB Mutations in Korean Siblings with Maple Syrup Urine Disease Showing Mild Clinical Presentation

Maple syrup urine disease (MSUD) is a disorder that involves the metabolism of branched chain amino acids, arising from a defect in branched-chain alpha-keto acid dehydrogenase complex. Mutations have been identified in the BCKDHA, BCKDHB, or DBT genes, which encode different subunits of the BCKDH complex. Although encephalopathy and progressive neurodegeneration are its major manifestations, the severity of the disease may range from the severe classic type to milder intermediate variants. We report two Korean siblings with the milder intermediate MSUD who were diagnosed with MSUD by a combination of newborn screening tests using tandem mass spectrometry and family genetic screening for MSUD. At diagnosis, the patients' plasma levels were elevated for leucine, isoleucine, valine, and alloisoleucine, and branched-chain alpha-keto acids and branched-chain alpha-hydroxy acids were detected in their urine. BCKDHA, BCKDHB, and DBT analysis was performed, and two novel mutations were identified in BCKDHB. Our patients were thought to have the milder intermediate variant of MSUD, rather than the classic form. Although MSUD is a typical metabolic disease with poor prognosis, better outcomes can be expected if early diagnosis and prompt management are provided, particularly for milder forms of the disease.

Annual Report on External Quality Assessment of Biochemical Genetics in Korea (2013) / 임상검사와정도관리

Two trials of external quality assessment (EQA) of conventional newborn screening tests for phenylketonuria, galactosaemia, congenital adrenal hyperplasia, maple syrup urine disease, homocystinuria, and congenital hypothyroidism, as well as of newborn screening tests using tandem mass spectrometry were performed in 2013. A total of 32 specimens in the form of dried blood spots were distributed to 16 laboratories and the response rate of these laboratories was 100%. Total T4, free T4, 17-hydroxyprogesterone, leucine, isoleucine, galactose, methionine, alanine, C8/C2, C8/C10, and C5-OH did not meet the accepted performance criteria. The mean, standard deviation, coefficient of variation, median, and cut-offs were evaluated for each analyte in the newborn screening tests. Two trials of EQA for the analyses of methylmalonic acid, vanillylmandelic acid, very long fatty acids, organic acids, and amino acids were also performed. A well-designed EQA program and continuous education would improve the performance of biochemical genetic tests.