La miastenia neonatal transitoria es una complicación rara de la miastenia gravis materna.
Alrededor del 10-15% de los niños nacidos de madres con anticuerpos anti receptor de acetil-colina (AChR), y menos frecuentemente anti kinasa específica muscular (MuSK).
Los síntomas suelen ser evidentes a partir del 3º dia de vida, y en casi todos los casos existe paresia facial bilateral y dificultades para la succión. Los síntomas suelen desaparecer al mes de vida.
No obstante en un grupo reducido de pacientes se puede producir un cuadro mucho más grave, con artrogriposis fetal y paresia bulbofacial persistente hasta la edad adulta, llamado síndrome de inactivación fetal de AChR, por anticuerpos contra la subunidad gamma fetal, que es reemplazada en el adulto por la subunidad epsilon.
La inactivación del receptor se produce por la exposición a los anticuerpos específicos en un período crítico del desarrollo.
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https://www.sciencedirect.com/science/article/pii/S0002929707631371
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