Double trouble: spinal muscular atrophy type II and seropositive myasthenia gravis in the same patient.

Autosomal recessive proximal spinal muscular atrophy is caused by deletions in the survival of motor neuron (SMN1) gene, while autoimmune myasthenia gravis is an acquired disorder. An association between these two diseases has not been reported. Our patient with intermediate spinal muscular atrophy (SMA type II) did not need alimentary or respiratory aid until age 51 when he suddenly developed bulbar weakness and respiratory insufficiency. Seropositive myasthenia gravis was confirmed and the corresponding symptoms resolved on treatment.