Screening for autoantibodies against voltage-gated calcium channel P/Q (VGCC-P/Q), is used in the investigation of patients with suspected paraneoplastic neuropathy, with Lambert-Eaton myasthenic syndrome and cerebral dysfunction.
There are several types of voltage-gated calcium channels that resemble each other but are not completely identical, the most common being the N-type found in cells throughout the brain and peripheral nervous system and the P/Q type found in Purkinje neurons in the cerebellum and in the granule cells of the cerebellum.
Antibodies against the voltage-gated calcium channels appear in paraneoplastic neuropathy e.g. in small cell lung cancer but may also be present without the presence of tumors. Antibodies against the voltage-gated calcium channels are observed in patients with Lambert-Eaton myasthenic syndrome and cerebrovascular dysfunction. These are mainly VGCC-P/Q antibodies that are of clinical significance, whereas the importance of VGCC-N antibodies is less well known. Its classic clinical triad is the weakness of the proximal muscles, the absence of reflexes, and the dysfunction of the autonomic nervous system.
See also: Voltage-Gated Calcium Channel-N (VGCC-N)