Congenital slow channel syndrome (Q92750)

In slow channel syndrome, a congenital myasthenic syndrome subtype with a postsynaptic defect, there is selectively severe involvement of cervical and wrist and finger extensor muscles in most cases. Cranial muscles only mildly affected; slowly progressive course. Worsened by long-term pyridostigmine therapy; little or no response to edrophonium. Dominant inheritance in nearly all cases. Repetitive nerve stimulation shows decrement and repetitive compound muscle action potentials.