RESUMO
El síndrome de QT largo es causa de muerte súbita por arritmias ventriculares y puede ser de origen congénito o adquirido. Entre las causas adquiridas, las más frecuentes son los trastornos iónicos y los fármacos. En esta presentación se describe el caso de una paciente con síndrome de QT largo secundario a hipocalcemia por hipoparatiroidismo primario. Es indispensable la detección de posibles causas secundarias y reversibles de síndrome de QT largo, que son más frecuentes que el origen genético, dado que tienen tratamiento etiológico eficaz y se evitan medidas diagnósticas y terapéuticas innecesarias.
Long-QT syndrome is a congenital or acquired disorder that produces sudden death due to ventricular arrhythmias. Electrolyte disturbances and medications are the most common causes of acquired long-QT syndrome. We describe the case of a patient with long-QT syndrome secondary to hypocalcemia caused by primary hypoparathyroidism. The secondary causes of long-QT syndrome should be thoroughly examined as they are more common than the genetic causes. Also, as they are reversible with adequate etiological treatment, their correct identification avoids unnecessary diagnostic and therapeutic measures.
RESUMO
Congenital long QT syndrome is mainly caused by mutations in the KCNQ1, KCNH2 and SCN5A genes. The aim of this study was to investigate the prevalence of mutations in these three genes in patients with long QT syndrome or idiopathic ventricular fibrillation seen at our center. The study included nine patients with long QT syndrome and four with idiopathic ventricular fibrillation. The first-degree relatives of genotype-positive probands were also investigated. Missense mutations were found in seven patients with long QT syndrome and two with idiopathic ventricular fibrillation. Overall, 71.4% of mutations were in KCNH2 and 28.6% were in SCN5A. No mutations in KCNQ1 were found. Only two mutations had been previously observed. Mutations were also found in six of the 19 relatives studied. In conclusion, our initial experience shows that genetic testing had a high sensitivity for diagnosing long QT syndrome. Mutations were found most frequently in the KCNH2 gene.
Assuntos
Testes Genéticos , Síndrome do QT Longo/genética , Adolescente , Criança , Pré-Escolar , Feminino , Genótipo , Humanos , Lactente , Masculino , Pessoa de Meia-Idade , Mutação , Adulto JovemRESUMO
El síndrome de QT largo congénito tiene su causa principal en mutaciones de los genes KCNQ1, KCNH2 y SCN5A. Nos proponemos analizar la prevalencia de mutaciones en estos genes en nuestra serie de pacientes con síndrome de QT largo y fibrilación ventricular idiopática. Se incluyó a 9 pacientes con síndrome de QT largo y 4 con fibrilación ventricular idiopática. Se estudió a los familiares de primer grado de los probandos con genotipo positivo. Encontramos mutaciones missense en 7 pacientes con síndrome de QT largo y en 2 con fibrilación ventricular idiopática. El 71,4% de las mutaciones fueron en KCNH2 y el 28,6% en SCN5A. No se halló ninguna mutación en KCNQ1. Sólo dos mutaciones estaban previamente descritas. En 6 familiares de los 19 estudiados se encontró una mutación. En conclusión, en nuestra experiencia inicial el estudio genético tuvo una alta sensibilidad para el diagnóstico de síndrome de QT largo. El gen más frecuentemente mutado fue KCNH2 (AU)
Congenital long QT syndrome is mainly caused by mutations in the KCNQ1, KCNH2 and SCN5A genes. The aim of this study was to investigate the prevalence of mutations in these three genes in patients with long QT syndrome or idiopathic ventricular fibrillation seen at our center. The study included nine patients with long QT syndrome and four with idiopathic ventricular fibrillation. The first-degree relatives of genotype-positive probands were also investigated. Missensemutationswere found in seven patients with long QT syndrome and two with idiopathic ventricular fibrillation. Overall, 71.4% of mutations were in KCNH2 and 28.6% were in SCN5A. No mutations in KCNQ1 were found. Only two mutations had been previously observed. Mutations were also found in six of the 19 relatives studied. In conclusion, our initial experience shows that genetic testing had a high sensitivity for diagnosing long QT syndrome. Mutations were found most frequently in the KCNH2 gene (AU)
