The Lambert–Eaton myasthenic syndrome (LEMS) is caused by serum IgG anti-voltage-gated calcium channel (anti-VGCC) antibodies.¹ Although transient neonatal myasthenia gravis, caused by passive placental transfer of maternal anti-acetylcholine receptor (anti-AChR), is well recognised,² as far as I am aware, this phenomenon has not previously been reported in LEMS.

A diagnosis of LEMS was made in a woman at the age of 25 years. She had noted difficulty in keeping up with other children since she was 13. Two years later, she became aware …