Intrafamilial variation in clinical manifestations and response to salbutamol in siblings with congenital myasthenic syndrome caused by DOK7 mutations

The congenital myasthenic syndromes (CMS) are a heterogeneous group of disorders arising from genetic defects in presynaptic, synaptic, and postsynaptic proteins of the neuromuscular junction (NMJ) resulting in variable and characteristically fatigable muscle weakness affecting limb, ocular, bulbar, trunk, and respiratory muscles from early life. DOK7 mutation resulting in synaptic and postsynaptic CMS clinically presents with limb-girdle myasthenia with sparing of facial and EOM. They characteristically worsen with conventional treatment and show excellent response to salbutamol/ ephedrine. Here we present a case highlighting a varied presentation beginning in late childhood and its evolution to reveal its congenital nature and subsequent management with salbutamol.