RESUMEN
We investigated electrophysiologically the unaffected parents of patients with recessive myotonia congenita. We studied 18 families, in nine of which the diagnosis was confirmed by molecular genetics. Brief myotonic discharges were present in at least one parent in 67% of the families. Fathers were more likely than mothers to show these discharges. The difficulty in distinguishing very mildly affected parents with dominant myotonia congenita from the heterozygous carriers of recessive myotonia congenita is stressed.
Asunto(s)
Genes Recesivos , Heterocigoto , Miotonía Congénita/genética , Miotonía Congénita/fisiopatología , Potenciales de Acción , Canales de Cloruro/genética , Electromiografía , Padre , Femenino , Humanos , Masculino , Madres , Músculo Esquelético/fisiopatología , Mutación , Miotonía Congénita/diagnósticoRESUMEN
Twenty-five Turkish patients with recessive myotonia congenita (RMC), 16 of whom had genetic confirmation, were studied. Nineteen had transient weakness. In the upper extremities, onset age of transient weakness was usually in the early teens. All untreated RMC patients had a compound muscle action potential decrement of > or =25%, usually above 50%, with repetitive nerve stimulation at 10/s for 5 s. Patients with other nondystrophic diseases with myotonia, except 1 patient with dominant myotonia congenita, had no transient weakness and a CMAP decrement below 25%.