LGI4, also known as leucine-rich glioma-inactivated protein 4, is a 537 amino acid secreted glycosylated protein that is widely expressed, with highest levels found within the nervous system. Interestingly, siRNA knockdown studies of LGI4 expression in Schwann cells have been shown to result in the inhibition of myelination, thus suggesting that LGI4 is an essential component of myelin formation and axon segregation. LGI4 shares significant homology with its other family members, LGI1, LGI2 and LGI3. Significantly, mutations in the gene encoding LGI1 have been linked to human temporal lobe epilepsy and, given the sequence similarity of LGI4, it is likely that it also may be implicated in the pathology of seizures. LGI4 is localized subcellularly to the Golgi, ER and vesicles. There are two isoforms of LGI4 that are produced as a result of alternative splicing events.