Genetic cause of nerve disease with self-biting in German Spitz dogs

Abstract

Hereditary sensory and autonomic neuropathies (HSAN) represent a group of genetic diseases affecting the peripheral nervous system. In humans, at least 16 loci have been associated with the disorder but do not explain the disease origin of all patients. In dogs, similar conditions have been documented for decades in various breeds with a severe impact on life quality and are often referred to as acral mutilation syndrome (AMS). Causal variants in three genes have been identified to date, suggesting larger genetic heterogeneity in the dog population. Our aim was to explain the genetic etiology of an early-onset HSAN/AMS in a purebred German Spitz. The affected dog showed progressive loss of pain sensation in the distal extremities, which led to intense licking, biting, and self-mutilation of digits and paw pads. Whole-genome sequencing identified a single candidate causal variant on chromosome 4 in the RETREG1 gene (c.656C>T, p.Pro219Leu). This missense variant was previously recognized as deleterious in a mixed breed dog family with similar clinical signs. Haplotype analyses and targeted genotyping revealed a likely German Spitz ancestry of these mixed breed dogs. Further screening of an extensive cohort of ~900 000 dogs of various breeds hinted at the variant allele origin in the German Spitz breed. Disruption of RETREG1 inhibits endoplasmic reticulum turnover and leads to neuron degeneration. Our findings provide evidence that this variant underlies the recessive form of HSAN/AMS in the German Spitz and support the use of whole-genome sequencing-based veterinary precision medicine for early diagnosis and prevention via a genetic test.