Association of Mutations in a Lysosomal Protein with Classical Late-Infantile Neuronal Ceroid Lipofuscinosis

TLDR

Classical late‑infantile neuronal ceroid lipofuscinosis (LINCL) is a fatal neurodegenerative disease whose defective gene has remained elusive. The study determined a molecular basis for LINCL using an approach applicable to other lysosomal storage diseases. The authors used mannose‑6‑phosphate affinity to isolate a lysosomal protein that is absent in LINCL patients. The identified protein is a pepstatin‑insensitive lysosomal peptidase whose activity is deficient in LINCL, and mutations in its gene were found in patients but not in controls.

Abstract

Classical late-infantile neuronal ceroid lipofuscinosis (LINCL) is a fatal neurodegenerative disease whose defective gene has remained elusive. A molecular basis for LINCL was determined with an approach applicable to other lysosomal storage diseases. When the mannose 6-phosphate modification of newly synthesized lysosomal enzymes was used as an affinity marker, a single protein was identified that is absent in LINCL. Sequence comparisons suggest that this protein is a pepstatin-insensitive lysosomal peptidase, and a corresponding enzymatic activity was deficient in LINCL autopsy specimens. Mutations in the gene encoding this protein were identified in LINCL patients but not in normal controls.