RESUMEN
OBJECTIVE: Barth syndrome, an X-linked disorder that is characterized by cardiomyopathy, neutropenia, skeletal myopathy, and growth delay, is caused by mutations in the taffazin gene at Xq28 that result in cardiolipin deficiency and abnormal mitochondria. The clinical phenotype in Barth syndrome has not been characterized systematically, and the condition may be underrecognized. We sought to evaluate extent of cardioskeletal myopathy, potential for arrhythmia, delays in growth, and biochemical correlates of disease severity in patients with this disorder. METHODS: We conducted an observational, cross-sectional study of the largest cohort of patients with Barth syndrome to date (n = 34; age range: 1.2-22.6 years). Evaluation included echocardiography, electrocardiography (standard and signal-averaged), microvolt T wave alternans analysis, biochemical and hematologic laboratory analyses, and physical therapy evaluation of skeletal myopathy. RESULTS: Family history was positive for confirmed or suspected Barth syndrome in 63%. Ninety percent of patients had a clinical history of cardiomyopathy (mean age at diagnosis of cardiomyopathy: 5.5 months; at genetic confirmation of Barth syndrome: 4.6 years). Echocardiography revealed a mean ejection fraction of 50% +/- 10%, mean fractional shortening of 28% +/- 5%, and mean left ventricular end-diastolic volume z score of 1.9 +/- 1.8. Left ventricular morphology demonstrated increased trabeculations or true noncompaction in 53%. Of 16 patients who were evaluated at > or = 11 years of age, 7 (43%) had documented ventricular arrhythmia. Growth deficiency was present (mean weight percentile: 15%; mean height percentile: 8%). Laboratory analysis revealed low total white blood cell count (absolute count: < 4000 cells per microL) in 25% of those who were not on granulocyte colony-stimulating factor. Hypocholesterolemia was present in 24%, decreased low-density lipoprotein cholesterol in 56%, low prealbumin in 79%, and mildly elevated creatine kinase in 15%. CONCLUSIONS: Our cohort demonstrated clinical variability, but most had cardiomyopathy and diminished growth velocity, with a propensity toward neutropenia and low cholesterol. There was increased incidence of ventricular arrhythmia, predominantly in adolescents and young adults. Barth syndrome should be considered when boys present with cardiomyopathy, especially when associated with increased left ventricular trabeculations, neutropenia, skeletal muscle weakness, or family history indicating an X-linked pattern of inheritance.
Asunto(s)
Cardiomiopatía Dilatada/patología , Enfermedades Genéticas Ligadas al Cromosoma X/patología , Aciltransferasas , Adolescente , Adulto , Cardiomiopatía Dilatada/diagnóstico por imagen , Cardiomiopatía Dilatada/genética , Niño , Preescolar , LDL-Colesterol/deficiencia , Estudios de Cohortes , Creatina Quinasa/sangre , Estudios Transversales , Análisis Mutacional de ADN , Enanismo/genética , Enanismo/patología , Ecocardiografía , Electrocardiografía , Enfermedades Genéticas Ligadas al Cromosoma X/diagnóstico por imagen , Enfermedades Genéticas Ligadas al Cromosoma X/genética , Genotipo , Factor Estimulante de Colonias de Granulocitos/uso terapéutico , Fuerza de la Mano , Ventrículos Cardíacos/patología , Humanos , Lactante , Leucopenia/tratamiento farmacológico , Leucopenia/genética , Masculino , Debilidad Muscular/genética , Debilidad Muscular/patología , Fenotipo , Prealbúmina/deficiencia , Proteínas/genética , Volumen Sistólico , Síndrome , Factores de Transcripción/deficiencia , Factores de Transcripción/genéticaRESUMEN
Catecholaminergic polymorphic ventricular tachycardia (CPVT) is a rare clinical entity in children. Occult myocarditis has not been previously implicated as an etiologic agent. A 3-year-old female presents with a presumed breath-holding spell and is found to have ventricular fibrillation requiring DC cardioversion. An invasive electrophysiological study was performed demonstrating the absence of inducible ventricular arrhythmias. Low dose epinephrine confirmed the presence CPVT. Right ventricular endomyocardial biopsies sent for polymerase chain reaction (PCR) analysis demonstrated the presence of adenoviral DNA. The authors hypothesize that occult myocarditis may be the inciting agent for CPVT in children.