Calcium Channel Antibody, N-Type Unit Converter

N-type calcium channel antibody is an autoantibody that targets N-type voltage-gated calcium channels (VGCCs), also known as Cav2.2 channels. These channels are located at synaptic nerve terminals, dendrites, and neuroendocrine cells throughout the nervous system. They control calcium entry into nerve endings, which triggers the release of neurotransmitters such as acetylcholine, norepinephrine, and dopamine.

When the immune system produces antibodies against these channels, the antibodies cause the channels to be internalized and removed from the nerve terminal surface. This reduces calcium flow and impairs neurotransmitter release, leading to neurological and autonomic dysfunction.

N-type VGCC antibodies are distinct from P/Q-type VGCC antibodies, which are the primary diagnostic marker for Lambert-Eaton myasthenic syndrome (LEMS). N-type antibodies are found in approximately 30-40% of LEMS patients and almost always co-occur with P/Q-type antibodies. They are also associated with a broader range of neurological conditions, including autoimmune encephalitis, peripheral neuropathy, and autonomic neuropathy.

N-type calcium channel antibodies are produced by B lymphocytes of the immune system. In paraneoplastic cases, small cell lung cancer or other tumors express calcium channels on their surface, triggering the immune system to produce cross-reactive antibodies. In non-paraneoplastic cases, the antibodies arise from autoimmune dysregulation, often associated with the HLA-B8, HLA-DR3, and HLA-DQ2 genetic haplotypes.