A missense change in the ATG4D gene links aberrant autophagy to a neurodegenerative vacuolar storage disease

PLoS Genet. 2015 Apr 15;11(4):e1005169. doi: 10.1371/journal.pgen.1005169. eCollection 2015 Apr.


Inherited neurodegenerative disorders are debilitating diseases that occur across different species. We have performed clinical, pathological and genetic studies to characterize a novel canine neurodegenerative disease present in the Lagotto Romagnolo dog breed. Affected dogs suffer from progressive cerebellar ataxia, sometimes accompanied by episodic nystagmus and behavioral changes. Histological examination revealed unique pathological changes, including profound neuronal cytoplasmic vacuolization in the nervous system, as well as spheroid formation and cytoplasmic aggregation of vacuoles in secretory epithelial tissues and mesenchymal cells. Genetic analyses uncovered a missense change, c.1288G>A; p.A430T, in the autophagy-related ATG4D gene on canine chromosome 20 with a highly significant disease association (p = 3.8 x 10-136) in a cohort of more than 2300 Lagotto Romagnolo dogs. ATG4D encodes a poorly characterized cysteine protease belonging to the macroautophagy pathway. Accordingly, our histological analyses indicated altered autophagic flux in affected tissues. The knockdown of the zebrafish homologue atg4da resulted in a widespread developmental disturbance and neurodegeneration in the central nervous system. Our study describes a previously unknown canine neurological disease with particular pathological features and implicates the ATG4D protein as an important autophagy mediator in neuronal homeostasis. The canine phenotype serves as a model to delineate the disease-causing pathological mechanism(s) and ATG4D function, and can also be used to explore treatment options. Furthermore, our results reveal a novel candidate gene for human neurodegeneration and enable the development of a genetic test for veterinary diagnostic and breeding purposes.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Autophagy / genetics*
  • Base Sequence
  • Brain / metabolism
  • Brain / pathology
  • Cysteine Endopeptidases / chemistry
  • Cysteine Endopeptidases / genetics*
  • Cysteine Endopeptidases / metabolism
  • Dogs
  • Molecular Sequence Data
  • Mutation, Missense*
  • Neurodegenerative Diseases / genetics*
  • Neurodegenerative Diseases / pathology
  • Neurodegenerative Diseases / veterinary
  • Vacuoles / genetics
  • Vacuoles / metabolism*
  • Zebrafish


  • Cysteine Endopeptidases

Grants and funding

This study was partly supported by a grant from the Albert-Heim-Foundation (http://www.albert-heim-stiftung.ch/) to TL, by grants to HL from the Academy of Finland (http://www.aka.fi/en-GB/A/), ERCStG (260997) (http://erc.europa.eu/funding-and-grants), the Sigrid Juselius Foundation (http://www.sigridjuselius.fi/foundation), Biocentrum Helsinki (http://www.helsinki.fi/biocentrum/) and The Jane and Aatos Erkko Foundation (http://www.jaes.fi/en/), by a grant from the Biomedicum Helsinki Foundation (http://www.biomedicum.com/) to KK, by grants to JK from the Swedish Research Council (http://www.vr.se/) and Swedish Brain Foundation (http://www.hjarnfonden.se/), and by a postdoctoral grant to GC from the Swedish Brain Foundation (http://www.hjarnfonden.se/). TL received a Humboldt Research Award from the Alexander von Humboldt Foundation (http://www.humboldt-foundation.de). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.