Through the generosity of the AKC-CHF and the PWD breeders, we have been able to find the genetic defect that causes puppy eye syndrome (microphthalmia syndrome) in the Portuguese Water Dog. The defect consists of a large insertion and deletion within a gene that is responsible for ocular development and bone marrow regulation.
We have developed a genetic test that we have been offering through PennGen (www.vet.upenn.edu/PennGen) over the last few years. Since the beginning, we have tested 1757 PWDs of which 1460 were normal, 293 were carriers and 4 affected. This means that the defective allele (one copy of the defective gene) is still in the population at 8.8%, which in turn means that there are less than 0.7% affected dogs in the population. This number is probably lower now since breeders have been able to make informed breeding decisions because of the available testing. A paper has been written describing the findings and has been submitted for publication.
Publications:
Leonardo Murgiano, Esha Banjeree, Cynthia O’Connor, Petra Werner, Jessica K Niggel, Gustavo D Aguirre, Margret L Casal, Keiko Miyadera, A naturally occurring canine model of syndromic congenital microphthalmia, G3 Genes|Genomes|Genetics, 2024 https://doi.org/10.1093/g3journal/jkae067
Final Microphthalmia and Delayed Growth Syndrome in the Portuguese Water Dog