 The primary aim of the study is to assess the genotype - phenotype correlations of the CNS manifestations of late infantile neuronal ceroid lipofuscinosis LINCL, a fatal, rare, recessive disorder of the CNS in children. This study will be accomplished by comparing the genotype to a neurologic assessment and Weill Cornell LINCL scale, the UBDRS scale, the standardized CHQ quality of life scale, and the Mullen scale; magnetic resonance imaging MRI; and routine clinical evaluations. This study is designed to run parallel to a separate study which is being done by the Department of Genetic Medicine, which will use gene transfer to treat the central nervous system CNS manifestations of late infantile neuronal ceroid lipofuscinosis. 