TPP1 deficiency: Rare cause of isolated childhood-onset progressive ataxia

Neuronal ceroid lipofuscinoses (NCLs) are neurodegenerative disorders characterized by lysosomal ceroid deposition. Historically, NCLs were classified by onset age and electron microscopy abnormalities as infantile, late infantile, juvenile, and adult.1,2 Molecular techniques have broadened diagnostic subgroups with identification of at least 13 NCL genes (), though categorization remains difficult due to wide-ranging genetic, allelic, and phenotypic heterogeneity.1,2 Acknowledgment: The authors thank the patient and her family; Dr. Nathaniel Chuang for providing the MRI figure; and Carolyn Smith for providing the patient's testing costs.