Microphthalmia
A variant in the RBP4 gene causes multiple eye abnormalities due to a fetal serum vitamin A (retinol) deficiency. Vitamin A is needed to synthesize retinoic acid (RA), a potent molecule needed for the proper development of the eye and other tissues. The eye is the most sensitive among organs to reduced RA levels during the formation of the embryo.
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Signs and symptoms
Affected dogs may have small or undeveloped eyes or other defects of the retina, iris, or optic nerve. Because their vision is impaired, this may cause dogs to often hesitate on stairs, bump into doorways or walls, have difficulty fetching toys, and be disoriented if the furniture is moved.
Microphthalmia may be observed at birth or as soon as the puppies open their eyes, and other changes may be noted on an ophthalmic exam at a few weeks of age, though they are present from birth.Uncover health risks with Embark
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Diagnosis
Microphthalmia can be observed during a basic eye examination; however, a veterinary ophthalmologist may be needed for a comprehensive diagnosis of the more subtle changes.
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Treatment
There is no specific treatment for Microphthalmia.
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What to do if your dog is at risk
Actions
- Talk to your vet about your dog’s microphthalmia result so you can discuss whether any signs are present and plan care if needed.
- Some dogs with this condition may have limited vision or be blind, while others can still see well enough to adapt easily.
- Help your dog move safely by keeping furniture in consistent locations, using verbal cues, and keeping them on a leash in unfamiliar areas.
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Genetic Information
This variant was first identified in the Soft Coated Wheaten Terrier.
Microphthalmia is transmitted as an autosomal recessive trait with penetrance determined by the maternal genotype.
Gene names:
RBP4 Exon 2 ‐ chr
Inheritance type:
recessive
Citations:
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Breeds affected
This health condition affects the following breeds
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