Neuronal ceroid lipofuscinoses (NCLs) are a group of lysosomal neurodegenerative disorders that have in common the characteristic accumulation of abnormal storage material. Old clinical classification based on age of onset is now being revisited with the quickly accumulating knowledge of the various genetic defects that underlie this group of genetically heterogeneous disorders. We report our linkage data on a family with late-infantile NCL and show that the disease in this family is due to a homozygous novel mutation in the most recently described NCL gene (MFSD8). We use clinical data from our patients and the few others that have previously been reported to delineate the phenotype associated with mutations in this gene. We conclude that the phenotype is fairly consistent, which is a helpful guide to clinicians as they decide on the most cost-effective molecular testing strategies for NCLs.