The Juvenile form of Batten disease is a neurodegenerative disease with symptoms starting in the first decade and ending in death in the third decade of life. The gene defective in this form of Batten disease, <i>CLN3</i>, is conserved in eukaryotes, suggesting that the gene product serves a basic function in the cell, though the function is unknown. The gene discussed is CLN3; the disease is juvenile neuronal ceroid lipofuscinosis.