Deletion in the Bardet-Biedl Syndrome Gene TTC8 Results in a Syndromic Retinal Degeneration in Dogs

Genes (Basel). 2020 Sep 18;11(9):1090. doi: 10.3390/genes11091090.


In golden retriever dogs, a 1 bp deletion in the canine TTC8 gene has been shown to cause progressive retinal atrophy (PRA), the canine equivalent of retinitis pigmentosa. In humans, TTC8 is also implicated in Bardet-Biedl syndrome (BBS). To investigate if the affected dogs only exhibit a non-syndromic PRA or develop a syndromic ciliopathy similar to human BBS, we recruited 10 affected dogs to the study. The progression of PRA for two of the dogs was followed for 2 years, and a rigorous clinical characterization allowed a careful comparison with primary and secondary characteristics of human BBS. In addition to PRA, the dogs showed a spectrum of clinical and morphological signs similar to primary and secondary characteristics of human BBS patients, such as obesity, renal anomalies, sperm defects, and anosmia. We used Oxford Nanopore long-read cDNA sequencing to characterize retinal full-length TTC8 transcripts in affected and non-affected dogs, the results of which suggest that three isoforms are transcribed in the retina, and the 1 bp deletion is a loss-of-function mutation, resulting in a canine form of Bardet-Biedl syndrome with heterogeneous clinical signs.

Keywords: BBS8; Bardet–Biedl syndrome (BBS); ciliopathy; primary cilia; progressive retinal atrophy (PRA); retinitis pigmentosa.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Bardet-Biedl Syndrome / etiology*
  • Bardet-Biedl Syndrome / pathology
  • Cytoskeletal Proteins / genetics*
  • Dogs
  • Female
  • Gene Deletion*
  • Male
  • Retinal Degeneration / etiology*
  • Retinal Degeneration / pathology


  • Cytoskeletal Proteins