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Canine Mendelian disease record

May-Hegglin Anomaly (MHA)

May-Hegglin Anomaly (MHA). Autosomal dominant. Observed in 0 of 266 breeds tested in the Sniff Atlas, with measured variant frequencies drawn from 242,623 dogs (Donner 2023). Whether a dog carrying this variant is at risk depends on the disease’s inheritance pattern; outcome also depends on penetrance, modifiers, and environment. The frequencies below describe variant prevalence, not confirmed disease incidence.

OMIA identifier
OMIA:001608-9615
Autosomal dominant
Source dataset
Sniff Atlas v1.0.1 / DOI
The human connection

A model of human macrothrombocytopenia and granulocyte inclusions with or without nephritis or sensorineural hearing loss

This is the canine counterpart of macrothrombocytopenia and granulocyte inclusions with or without nephritis or sensorineural hearing loss 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: An inherited giant platelet disorder with a complex phenotype characterized by congenital thrombocytopenia and possible subsequent manifestations of sensorineural hearing loss, presenile cataracts, elevation of liver enzymes, and/or progressive nephropathy often leading to end-stage renal disease (ESRD). Epstein syndrome, Fechtner syndrome, May-Hegglin anomaly and Sebastian syndrome, previously described as distinct disorders, represent some of the different clinical presentations of MYH9-RD.

In humans it is also called: FTNS, MATINS, MHA, MYH9-RD, SBS.

MONDO:0015912 OMIM 155100

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

Flatland et al. (2011): "An 8-year-old female spayed Pug dog was presented for evaluation of cutaneous lesions occurring secondary to immunosuppressive treatment of presumed immune-mediated thrombocytopenia. Abnormal hematologic findings included persistent thrombocytopenia, macrothrombocytes, and variably shaped, often fusiform, blue cytoplasmic inclusions in neutrophils."

Molecular genetics

Flatland et al. (2011): "genomic DNA sequencing analysis of the dog's MYH9 gene identified a single point mutation, resulting in substitution of lysine for glutamine at the 1841 amino acid position; this mutation is identical to one identified in people with MHA."

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 155100 Gene · OMIM 160775

Source: OMIA (Nicholas, Tammen & the Sydney Informatics Hub), entry OMIA:001608-9615, 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.

  1. May-Hegglin anomaly in a dog. · Vet Clin Pathol · 2011 · PMID 21554370

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.

Your breed

See what May-Hegglin Anomaly (MHA) looks like in your dog's breed.
Variant frequency by breed

Observed only in small-sample breeds

Maximum variant frequency 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.

Scope of this record

Scope

This record carries the breed-level carrier frequencies from the Donner 2023 cohort. Penetrance data (the fraction of at-risk dogs that develop the phenotype) is not yet quantified for this disease in the Sniff Atlas v1.0.1. The OMIA entry is the authoritative reference for the clinical phenotype, inheritance pattern, and gene assignment.

Predicted disease relevance at the per-dog level is UNPROVEN. The variant frequency is measured; phenotype outcome depends on 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:001608-9615.

  • 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:001608-9615 · Donner et al. 2023