January 20, 2021

Mechanism Connects Epilepsy and Enzyme Deficiency

Summary, originally published in JCI Insight

Researchers from Kyushu University’s Medical Institute of Bioregulation in collaboration with Nihon University, Yasuda Woman’s University, and Nagoya University now report a better understanding of a mechanism causing epilepsy in infants as the result of a deficiency of an enzyme known as inosine triphosphatase, or ITPA.

The new study could also give insight into possible risks for the 2% of the Japanese population in which both copies of the gene for ITPA produce versions with reduced activity.

Using mice that were genetically engineered such that ITPA production is disrupted only in the nervous system, the researchers found that ITPA deficiency led to a reduction in the negative charge inside the neurons when signals are not being sent, a phenomenon known as depolarization. This depolarization in turn results in frequent excitation of neurons and epileptic seizures in the mice.

The new results indicate that Early Infantile Epileptic Encephalopathy 35 (EIEE35), a neurological disorder characterized by epileptic seizures and associated with deficiency of ITPA, may involve cell membranes becoming more excitable because of depolarization caused by ITPA deficiency.

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