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Canine Mendelian disease record

Microphthalmia (Discovered in the Soft-Coated Wheaten Terrier)

Microphthalmia (Discovered in the Soft-Coated Wheaten Terrier). Autosomal recessive. Observed in 3 of 266 breeds tested in the Sniff Atlas, with measured carrier frequencies drawn from 242,663 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:002151-9615
Autosomal recessive
Source dataset
Sniff Atlas v1.0.1 / DOI
The human connection

A model of human microphthalmia, isolated, with coloboma 10

This is the canine counterpart of microphthalmia, isolated, with coloboma 10 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: Any microphthalmia, isolated, with coloboma in which the cause of the disease is a mutation in the RBP4 gene.

In humans it is also called: MCOPCB10, microphthalmia, isolated, with coloboma type 10, RBP4 microphthalmia, isolated, with coloboma.

MONDO:0014635 OMIM 615147OMIM 616428

Mapped from OMIA via the human disease's OMIM entry to the Mondo Disease Ontology (Monarch Initiative, CC-BY 4.0). Closely related human conditions exist for this gene. 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.

Molecular genetics

Comparison of the whole-genome sequence of one affected dog with the canine reference assembly in the candidate region eventually revealed the likely causal variant as "a 3-bp deletion (c.282_284del) in the gene encoding RBP4 gene, resulting in the loss of a single lysine (AAG codon) near the RBP amino terminus (p.K30del), in a charged segment preceding the lipocalin b-barrel domain (Figure 3). This is the 12th amino acid in the mature protein (K12del), after cleavage of the signal peptide, and it is highly conserved among vertebrates." (Kaukonen et al., 2018) "The maternal penetrance effect arises from an impairment in the sequential transfer of retinol across the placenta, via RBP encoded by maternal and fetal genomes. Our results demonstrate a mode of recessive maternal inheritance, with a physiological basis, and they extend previous observations on dominant-negative RBP4 alleles in humans [see MIM link above]." (Kaukonen et al., 2018)

Inheritance

Kaukonen et al. (2018): "The four affected litters are related in a single pedigree, with a transmission pattern suggesting an autosomal recessive mode of inheritance" (Kaukonen et al., 2018). However, the disease "manifests only if both the dam and the offspring carry homozygous mutation", i.e. this is a "Recessive RBP4 defect with maternal transmission" (Kaukonen et al., 2018)

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 615147 Disease · OMIM 616428 Gene · OMIM 180250

Source: OMIA (Nicholas, Tammen & the Sydney Informatics Hub), entry OMIA:002151-9615, doi:10.25910/2AMR-PV70 (CC-BY 4.0).

Signs & cross-references

How it presents

Catalogued in the Mondo disease ontology (the cross-species disease identity used by the Monarch Initiative) as microphthalmia, isolated, with coloboma 10 (MONDO:0014635).

Phenotype terms: Human Phenotype Ontology + Mammalian Phenotype Ontology; disease terms: Mondo (Monarch Initiative). Cross-references curated by OMIA (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.

  2. The Blue Book: Ocular disorders presumed to be inherited in purebred dogs. 13th Edition · https://ofa.org/wp-content/uploads/2022/10/ACVO-Blue-Book-2021.pdf · 2021

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 Microphthalmia (Discovered in the Soft-Coated Wheaten Terrier) 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 Microphthalmia (Discovered in the Soft-Coated Wheaten Terrier) looks like in your dog's breed.
Carrier frequency by breed

Top 3 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%10%20%
Russell Terrier6.5% · n 239
Soft Coated Wheaten Terrier3.8% · n 607
Chihuahua<0.1% · n 4,273
n = 5,119 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 Microphthalmia (Discovered in the Soft-Coated Wheaten Terrier) is measured; phenotype outcome depends on penetrance and modifiers.
▸ Full table with Wilson 95% confidence intervals
Breed Carrier frequency n tested
Russell Terrier 6.5% 239
Soft Coated Wheaten Terrier 3.8% 607
Chihuahua <0.1% 4,273

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

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 carrier 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:002151-9615.

  • 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:002151-9615 · Donner et al. 2023