The neuronal ceroid lipofuscinoses (NCLs) are a group of inherited neurodegenerative disorders characterized by the accumulation of autofluorescent lipopigment in neurons and other cell types. The biochemical basis of these diseases is unknown. Three main childhood forms are recognized: infantile (Santavuori-Haltia disease, CLN1), late infantile (Jansky-Bielschowsky disease, CLN2), and juvenile (Spielmeyer-Vogt-Sjögren, Batten disease, CLN3). The CLN1 gene has been mapped to chromosome 1p and CLN3 to chromosome 16p by linkage analysis (1, 2). The gene locus causing the classical late infantile form (CLN2) has not yet been mapped but has been excluded from both CLN1 and CLN3 loci (8). About 10% of NCL cases have atypical clinical features with most of these resembling the late infantile form.