Severe congenital X-linked myopathy with excessive autophagy secondary to an apparently synonymous but pathogenic novel variant.

X-linked myopathy with excessive autophagy is a rare inherited disease characterized by aberrant accumulation of autophagic vacuoles in skeletal muscle. Affected males usually show a slow progression and the heart is characteristically spared. We present four male patients from the same family with an extremely aggressive form of this disease, requiring permanent mechanical ventilation from birth. Ambulation was never achieved. Three died, one in the first hour of life, one at 7 years and one at 17 years, the last death being a consequence of heart failure. Muscle biopsy showed pathognomonic features of the disease in the 4 affected males. Genetic study found a novel synonymous variant in VMA21, c.294C>T (Gly98=). Genotyping was consistent with co-segregation with the phenotype in an X-linked recessive manner. An alteration of the normal splice pattern was confirmed by transcriptome analysis, proving that the apparently synonymous variant was the cause of this extremely severe phenotype.

[Spanish multicenter study: hyperammonemia not associated with inborn errors of metabolism in children]. / Estudio multicéntrico español: niños con hiperamoniemia no asociada a errores innatos del metabolismo.

INTRODUCTION: The hyperammonemic encephalopathy induced by causes different from inborn errors of metabolism is a relatively uncommon but severe complication. OBJETIVES: To study the characteristics of a secondary hyperammonemia episode to discern the triggering causes to get to the diagnosis, and the development in the therapeutic intervention. METHODS: A multicenter retrospective study of children with hyperammonemia unrelated to inborn errors of metabolism, conducted in Spanish hospitals. RESULTS: Nineteen patients were selected; hyperammonemia developed in infants under one year old in 47% of them, being diagnosed mostly with two or more symptoms. The most common clinical finding was an altered consciousness level similar to that of intoxication symptoms, followed by seizures. These clinical symptoms were present in 14 patients, with one of them or both. Twelve of the 19 patients were in treatment with more than two antiepileptic drugs routinely. All children were treated with protein restriction (n: 10), scavengers (n: 10) and/or carglumic acid (n: 12) for the treatment of hyperammonemia. CONCLUSIONS: This study suggests that secondary hyperammonemia could be underdiagnosed because it is only detected when severe symptoms appear. Risk seems to be higher in those patients receiving antiepileptic drugs or those critically ill with a restricted diet or incremented metabolism. The response to specific treatment is adequate but should be established earlier to avoid neurological sequelae of this entity.

INTRODUCCIÓN: la encefalopatía hiperamoniémica inducida por causas diferentes a los errores innatos del metabolismo es una complicación relativamente infrecuente, pero muy grave. OBJETIVOS: conocer las características de un episodio de hiperamoniemia secundaria, tratar de discernir las causas desencadenantes, cómo se llega al diagnóstico del episodio y cómo se desarrolla la actuación terapéutica. MÉTODOS: es un estudio multicéntrico retrospectivo de casos pediátricos con hiperamoniemia no relacionada con errores innatos del metabolismo, llevado a cabo en hospitales españoles. RESULTADOS: fueron seleccionados 19 pacientes y en un 47% el episodio de hiperamoniemia apareció en menores de un año, que fueron diagnosticados mayoritariamente con dos o más síntomas. La clínica más frecuente fue la de alteración del nivel de conciencia tipo intoxicación, seguida de las crisis convulsivas, sumando en ambas hasta 14 pacientes con alguna de ellas o las dos. Doce de los 19 pacientes utilizaban más de dos fármacos antiepilépticos de forma habitual. Todos los niños recibieron tratamiento con restricción proteica (n: 10), quelantes (n: 10) y/o ácido carglúmico (n: 12) para el tratamiento de la hiperamoniemia. CONCLUSIONES: este estudio sugiere que la hiperamoniemia secundaria puede estar infradiagnosticada y solo se detecta cuando aparece una sintomatología grave. Parecen ser pacientes de riesgo aquellos que reciben fármacos antiepilépticos o aquellos críticos con una alimentación restringida o un metabolismo elevado. La respuesta con tratamiento específico es adecuada pero debe ser precoz para evitar las secuelas neurológicas de esta entidad.

Sepiapterin reductase deficiency: a treatable mimic of cerebral palsy.

OBJECTIVE: Sepiapterin reductase deficiency (SRD) is an under-recognized levodopa-responsive disorder. We describe clinical, biochemical, and molecular findings in a cohort of patients with this treatable condition. We aim to improve awareness of the phenotype and available diagnostic and therapeutic strategies to reduce delayed diagnosis or misdiagnosis, optimize management, and improve understanding of pathophysiologic mechanisms. METHODS: Forty-three individuals with SRD were identified from 23 international medical centers. The phenotype and treatment response were assessed by chart review using a detailed standardized instrument and by literature review for cases for which records were unavailable. RESULTS: In most cases, motor and language delays, axial hypotonia, dystonia, weakness, oculogyric crises, and diurnal fluctuation of symptoms with sleep benefit become evident in infancy or childhood. Average age of onset is 7 months, with delay to diagnosis of 9.1 years. Misdiagnoses of cerebral palsy (CP) are common. Most patients benefit dramatically from levodopa/carbidopa, often with further improvement with the addition of 5-hydroxytryptophan. Cerebrospinal fluid findings are distinctive. Diagnosis is confirmed by mutation analysis and/or enzyme activity measurement in cultured fibroblasts. INTERPRETATION: Common, clinical findings of SRD, aside from oculogyric crises and diurnal fluctuation, are nonspecific and mimic CP with hypotonia or dystonia. Patients usually improve dramatically with treatment. Consequently, we recommend consideration of SRD not only in patients with levodopa-responsive motor disorders, but also in patients with developmental delays with axial hypotonia, and patients with unexplained or atypical presumed CP. Biochemical investigation of cerebrospinal fluid is the preferred method of initial investigation. Early diagnosis and treatment are recommended to prevent ongoing brain dysfunction.