title: Severe neonatal myasthenia due to maternal anti-MuSK antibodies.
abstract: Anti-MuSK antibodies have been reported in about 40-50% of patients with seronegative myasthenia gravis. Curiously, this condition has never been reported in association with fetal or transient neonatal myasthenia gravis, despite a known female predominance. We report the case of a 22-year-old woman who developed seronegative, mild steroid-responsive myasthenia gravis. When aged 26, she gave birth to a baby boy with neonatal myasthenia gravis characterized by hypotonia, stridor and sucking difficulties. Intubation was required for a few weeks. Anti-MuSK antibodies were assessed and found positive in both patients. Progressive hydramnios during the last trimester, with a decrease in spontaneous fetal mobility in the last weeks, long-lasting stridor, ptosis and occasional difficulties in swallowing liquids till two years of age, despite anti-MuSK antibodies becoming negative, suggest a fetal onset. The possible pathophysiology of this disorder, based on recent findings on the expression and function of MuSK protein, is reviewed.
authors.affiliation: Centre de Référence des maladies rares neuromusculaires Paris-Est, Institut de Myologie, Service de Neurologie Mazarin, Groupe Hospitalier Pitié-Salpêtrière, APHP, 47-83 Boulevard de l'hôpital, 75651 Paris Cedex 13, France. anthony.behin@psl.aphp.fr
authors.forename: Anthony
authors.initials: A
authors.lastname: Béhin
authors.forename: Michèle
authors.initials: M
authors.lastname: Mayer
authors.forename: Bouchera
authors.initials: B
authors.lastname: Kassis-Makhoul
authors.forename: Myriam
authors.initials: M
authors.lastname: Jugie
authors.forename: Caroline
authors.initials: C
authors.lastname: Espil-Taris
authors.forename: Xavier
authors.initials: X
authors.lastname: Ferrer
authors.forename: Lucienne
authors.initials: L
authors.lastname: Chatenoud
authors.forename: Pascal
authors.initials: P
authors.lastname: Laforêt
authors.forename: Bruno
authors.initials: B
authors.lastname: Eymard
mesh_terms: D000328:Adult; D000906:Antibodies / Q000009:adverse effects*; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D009034:Mother-Child Relations; D009157:Myasthenia Gravis / Q000139:chemically induced*; D020794:Receptor Protein-Tyrosine Kinases / Q000276:immunology*; D011950:Receptors, Cholinergic / Q000276:immunology*
chemical_list: D000906:Antibodies; D011950:Receptors, Cholinergic; C095714:MUSK protein, human; D020794:Receptor Protein-Tyrosine Kinases