ITPR1 and polyneuropathy: In 2016, we reported on serum ITPR1-IgG/anti-Sj in three male patients with (radiculo)polyneuropathy and, in one of them, neurogenic pain, consistent with the fact that ITPR1 has been shown to be expressed also in the anterior horn of the spinal cord, in the substantia gelatinosa, and in the motor, sensory (including the dorsal root ganglia) and autonomic peripheral nervous system.