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Canine Mendelian disease record

Trapped Neutrophil Syndrome (TNS)

Trapped Neutrophil Syndrome (TNS). Autosomal recessive. Observed in 2 of 266 breeds tested in the Sniff Atlas, with measured carrier frequencies drawn from 242,664 dogs (Donner 2023). Per-dog phenotype outcome depends on penetrance, modifiers, and environment; the carrier frequencies below describe variant prevalence, not disease incidence.

OMIA identifier
OMIA:001428-9615
Autosomal recessive
Source dataset
Sniff Atlas v1.0.1 / DOI
The human connection

A model of human Cohen syndrome

This is the canine counterpart of Cohen syndrome in people. That makes affected dogs a naturally-occurring model of the human disease, and it is part of why studying dogs moves medicine forward for everyone. It does not mean your dog has the human disease. It means the two share an underlying biology.

In people, the disease is described as: Cohen syndrome (CS) is a rare genetic developmental disorder characterized by microcephaly, characteristic facial features, hypotonia, non-progressive intellectual deficit, myopia and retinal dystrophy, neutropenia and truncal obesity.

In humans it is also called: COH1, Chs1.

MONDO:0008999 OMIM 216550

Mapped from OMIA via the human disease's OMIM entry to the Mondo Disease Ontology (Monarch Initiative, CC-BY 4.0). Sniff renders this as a model-of link; the canine disease remains the subject of this page.

About this disease

From OMIA's curated record

Documented in OMIA (Online Mendelian Inheritance in Animals). This describes the disease as recorded in the published literature, not a prediction for any individual dog. As of 2026-06-03.

Clinical features

Affected dogs present with fever, gastrointestinal signs, polyarthritis, joint effusion, and lameness and failure to thrive between 6 and 12 weeks of age and have a characteristic ‘ferret-like’ elongated face (Allen et al., 1996; Shearman & Wilton, 2011; Mizukami et al., 2012; Mason et al., 2014; Hegler et al., 2020). Proprioception and placing and hopping reflexes were markedly reduced, while skin reflex and deep pain sensations were normal (Mizukami et al., 2012). Decreased level of consciousness, astasia, and incontinence were also reported by Mizukami et al. (2012). Ill thrift and continued recurrent/chronic infections are hallmark features (Hegler et al., 2020). Dogs are commonly dying or being euthanised by one year of age (Wouda et al. 2010). [IT thanks DVM students Laura Sweeting and Tracy Yeung, who provided the basis of this contribution in April 2022]

Molecular genetics

Starting with a list of candidate genes based on comparative clinical signs in other species (especially humans), Shearman and Wilton (2011) used linkage analysis to eventually narrow the field down to the VPS13B gene. They "sequenced each of the 63 exons of VPS13B in affected and control dogs and found that the causative mutation in Border collies is a 4 bp deletion in exon 19 of the largest transcript that results in premature truncation of the protein."

Pathology

Hegler et al. (2020) and Mizukami et al. (2013) discuss trapped neutrophil syndrome as a condition characterised by retention of neutrophils in the bone marrow of Border Collies. Whilst understanding of pathophysiological mechanisms is incomplete, neutrophils are seen to move inadequately from their haemopoietic site in bone marrow, to peripheral circulation (Mizukami et al., 2012). The two major features are reduced circulating neutrophil numbers (peripheral neutropoenia) and intramedullary myeloid hyperplasia (Mason et al., 2014). Eosinophilia, monocytosis, hypercholesterolaemia and nRBC in circulation and non-regenerative anaemia are reported (Mizukami et al., 2013). Radiographs showed capsular joint swelling and heterogeneous metaphyseal radiolucencies in multiple joints and cytology revealed non-degenerate neutrophilic inflammation in multiple joints (Hegler et al., 2020). [IT thanks DVM students Laura Sweeting and Tracy Yeung, who provided the basis of this contribution in April 2022]

Prevalence

Mizukami et al. (2016) reported the frequency of the 4bp deletion allele as 0.059 in 500 Border collies in Japan.

Genetic testing

Having developed "a novel MAS-PCR assay targeting the VPS13B gene", Lerdkrai and Phungphosop (2023) demonstrated "for the first time that carriers of [the likely causal 4bp deletion (OMIA variant 478) for] TNS exist in Border Collies in Thailand". The authors also reported that their "assay is a reliable and cost-effective tool for diagnosing TNS based on VPS13B genotypes and is suitable for routine clinical practice."

Human analog

OMIA links this condition to its human counterpart in OMIM (Mendelian Inheritance in Man), the place to read across to the deeper human literature for the same biology.

Disease · OMIM 216550 Gene · OMIM 607817

Source: OMIA (Nicholas, Tammen & the Sydney Informatics Hub), entry OMIA:001428-9615, doi:10.25910/2AMR-PV70 (CC-BY 4.0).

The evidence

Published references

The peer-reviewed papers behind this disease, curated by OMIA. Starred entries are OMIA-designated landmark papers. Showing 6 of 16.

  2. Exploring the pathological mechanisms underlying Cohen syndrome. · Front Neurosci · 2024 · PMID 39010945

References curated by OMIA (Nicholas, Tammen & the Sydney Informatics Hub), doi:10.25910/2AMR-PV70 (CC-BY 4.0). Full list at the OMIA entry.

Predict a litter

Set each parent's status for Trapped Neutrophil Syndrome (TNS) and see the odds for their puppies. Single recessive variant, exact Mendelian math.

Parent A
Parent B
NNClear
NmCarrier
NmCarrier
mmAffected
Clear25%
Carrier50%
Affected25%

These are the genetic odds for one known variant, not a promise: a real litter varies around them, and penetrance or other genes can change whether the condition ever appears. Use it to avoid pairing two carriers and to keep a line healthy, not to engineer a dog. Inheritance mode per OMIA.
Your breed

See what Trapped Neutrophil Syndrome (TNS) looks like in your dog's breed.
Carrier frequency by breed

Top 2 well-sampled breeds (n ≥ 50)

Maximum per breed across variants in the Donner 2023 cohort, with . The list below is split into well-sampled breeds (n ≥ 50 tested) and small-sample breeds (n < 50, where the Wilson CI typically spans more than 20 percentage points and frequencies should not be compared directly to the well-sampled entries). Frequencies are population-level, not per-litter or per-line.

0%5%10%
Border Collie2.8% · n 6,714
Australian Kelpie0.96% · n 104
n = 6,818 dogs · Donner et al. 2023 carrier-screening cohort · Sniff Atlas
Each bar is one well-sampled breed; the whisker is its Wilson 95% CI, and fainter bars have wider intervals. Frequencies are population-level, not per-litter. Carrier status for Trapped Neutrophil Syndrome (TNS) is measured; phenotype outcome depends on penetrance and modifiers.
▸ Full table with Wilson 95% confidence intervals
Breed Carrier frequency n tested
Border Collie 2.8% 6,714
Australian Kelpie 0.96% 104

264 additional breeds in the Donner 2023 cohort were tested but showed no carriers.

Penetrance

From genotype to phenotype

Carrier status is not the same as disease status. Penetrance is the fraction of at-risk dogs that develop the phenotype. The Donner 2023 S4 table tracks this for 1 variant(s) underlying this disease in the cohort.

At-risk dogs evaluated
2
Phenotype confirmed
2
Penetrance range
not yet quantifiable

Fewer than 20 at-risk dogs evaluated; too few to state a penetrance figure.

Predicted disease relevance at the per-dog level is UNPROVEN. The carrier frequency is measured; phenotype outcome is governed by penetrance, environment, and modifier loci. Consult a veterinarian for clinical interpretation.

How to cite this record

Citations

If you use this record in published work, cite the Sniff Atlas (the published dataset that carries the breed-level carrier frequencies) and the upstream sources:

  • Sniff Atlas v1.0.1 for the per-breed carrier frequencies:

    Gehring, M. (2026). Sniff Atlas v1.0.1. Zenodo. https://doi.org/10.5281/zenodo.20566358. CC-BY 4.0.

  • OMIA for the disease definition, inheritance, and gene assignment:

    Nicholas, F. W., & Tammen, I. (2024). OMIA. Sydney Informatics Hub, The University of Sydney. https://doi.org/10.25910/2AMR-PV70. Entry: OMIA:001428-9615.

  • Donner et al. 2023 for the breed × variant carrier-frequency cohort:

    Donner, J., Freyer, J., Davison, S., Anderson, H., Blades, M., Honkanen, L., et al. (2023). Genetic prevalence and clinical relevance of canine Mendelian disease variants in over one million dogs. PLOS Genetics, 19(2), e1010651. https://doi.org/10.1371/journal.pgen.1010651.

Full citation formats (BibTeX, RIS, CITATION.cff) at sniff.world/cite.

Related

Related

Last updated
Sources: Sniff Atlas v1.0.1 · OMIA OMIA:001428-9615 · Donner et al. 2023