Canis lupus familiaris breed:greyhound Genome sequencing

Startle disease, or hyperekplexia, is a glycinergic disorder characterized by hypertonia and apnea that is triggered by noise and/or touch. The SLC6A5 gene encodes the presynaptic glycine transporter, and mutations of SLC6A5 have been associated with startle disease in humans, dogs, cattle, and mice. We identified a novel recessive startle disease in a family of Spanish greyhounds. Whole genome resequencing of an affected dog revealed a homozygous two base pair deletion in the eighth exon of SLC6A5. The deletion is predicted to cause a frameshift, p.S460FfsX47, leading to a premature stop codon that truncates over a third of the protein. Family members were genotyped for the deleterious allele, and findings were consistent with an autosomal recessive inheritance pattern. The pathogenic variant was absent from 34 unrelated greyhounds, 659 domestic dogs of pure and mixed breeds, and 54 wild canids, suggesting it occurred recently and may be private to the family. The findings of this study can be used to inform future breeding decisions and prevent dissemination of the startle allele in greyhounds.