Multiplex allele-specific polymerase chain reaction-based prevalence study of canine trapped neutrophil syndrome in Thailand

Abstract

Background and Aim: Trapped neutrophil syndrome (TNS) is an autosomal recessive genetic disorder found in Border Collies and is characterized by peripheral neutropenia and myeloid hyperplasia of bone marrow. The underlying cause of TNS is associated with a 4-base pair deletion mutation in the vacuolar protein sorting 13 homolog B (VPS13B) gene. In this study, we proposed and validated a novel multiplex allele specific-polymerase chain reaction (MAS-PCR) technique to assess the prevalence of TNS using VPS13B genotypes of Border Collies and Thai Ridgebacks in Thailand. Materials and Methods: We assessed the prevalence of TNS in 100 Border Collies and 30 Thai Ridgebacks using MAS-PCR-based allelic discrimination technique of the VPS13B gene. We then confirmed the VPS13B genotypes by direct DNA sequencing. Results: A total of 130 samples were successfully genotyped using MAS-PCR assays. Of the two dog breeds examined, the VPS13B mutation was present in Border Collies, whereas Thai Ridgebacks were unaffected by this mutation. In Border Collies, 96% of dogs tested had an intact VPS13B genotype, whereas the remaining individuals had a heterozygous mutation genotype, with prevalence and mutated VPS13B allele frequencies of 4% and 2%, respectively. Conclusion: Using a novel MAS-PCR assay targeting the VPS13B gene, this study demonstrates for the first time that carriers of TNS exist in Border Collies in Thailand. This assay is a reliable and cost-effective tool for diagnosing TNS based on VPS13B genotypes and is suitable for routine clinical practice. Keywords: Border Collie, multiplex allele specific-polymerase chain reaction assay, Thai Ridgeback, trapped neutrophil syndrome, vacuolar protein sorting 13 homolog B genotype.