Cytoband (human 19p13.13 CACNA1A) & (mouse 8qC3 Cacna1a).
Here I present: “Lambert-Eaton Syndrome“, Victor McKusick, Mendelian Inheritance in Man’, 1966. (CACNA1A) icd1=G70.8
Lambert–Eaton myasthenic syndrome (LEMS) is an autoimmune disorder characterized by muscle weakness of the limbs. It is also known as myasthenic syndrome, Eaton–Lambert syndrome, and when related to cancer, carcinomatous myopathy.
Normal Physiology.
In normal neuromuscular function, a nerve impulse is carried down the axon (the long projection of a nerve cell) from the spinal cord. At the nerve ending in the neuromuscular junction, where the impulse is transferred to the muscle cell, the nerve impulse leads to the opening of voltage-gated calcium channels (VGCC), the influx of calcium ions into the nerve terminal, and the calcium-dependent triggering of synaptic vesicle fusion with plasma membrane. These synaptic vesicles contain acetylcholine, which is released into the synaptic cleft and stimulates the acetylcholine receptors on the muscle. The muscle then contracts.
Pathology of LEMS.
In LEMS, antibodies against VGCC, particularly the P/Q-type VGCC and possibly the N-type VGCC, decrease the amount of calcium that can enter the nerve ending, resulting in reduced acetylcholine release in the neuromuscular junction. Apart from skeletal muscle, the autonomic nervous system also requires acetylcholine neurotransmission; this explains the occurrence of autonomic symptoms in LEMS.
There is evidence that Lambert-Eaton myasthenic syndrome (LEMS) is an autoimmune disorder, caused by antibodies against the calcium voltage-gated channel subunit alpha-1A (CACNA1A) gene product encoded on genomic coordinate 19:13,206,442 and cytoband 19p13.13 in humans.
