LGI1

The leucine-rich glioma inactivated -1 gene is rearranged as a result of translocations in glioblastoma cell lines. The protein contains a hydrophobic segment representing a putative transmembrane domain with the amino terminus located outside the cell. It also contains leucine-rich repeats with conserved cysteine-rich flanking sequences. This gene is predominantly expressed in neural tissues and its expression is reduced in low grade brain tumors and significantly reduced or absent in malignant gliomas.^[5]

Since its earliest discovery, the LGI1 gene has been implicated in the control of cancer metastasis and in a predisposition to epilepsy. Following genetic linkage studies placing the hereditary form of autosomal dominant partial epilepsy with auditory features (ADPEAF) on chromosome region 10q24^[6][7] mutation analysis of affected members in these families^[8][9][10] demonstrated LGI1 was a major cause of the disease.

More recently, LGI1 has been shown to be the major target of human autoantibodies^[11][12][13] which immunoprecipitate voltage-gated potassium channel complexes from mammalian brain tissue. LGI1 antibodies are found in patients with limbic encephalitis and in patients with faciobrachial dystonic seizures (FBDS). FBDS are a recently described form of epilepsy which is characterized by frequent, brief seizures which affect the arm and face. They appear to be preferentially responsive to immunotherapy over anti-epileptic drugs.

LGI1 has been shown to interact with ADAM22,^[14] and DLG4.^[14]