In addition, glutamate levels are elevated in the brains of JNCL patients and CLN3 mutant mice [59], [60], [61], and since astrocytes exclusively express glutamate synthetase in the CNS, altered enzyme levels could represent a key mechanism responsible for glutamate accumulation in the JNCL brain. The gene discussed is CLN3; the disease is juvenile neuronal ceroid lipofuscinosis.