Feline Caramel-colour Research Project Alfort School of Veterinary Medicine, France  

Thanks to breeders and owners, pedigree data, hairs and DNA samples were collected from 46 Caramel and Apricot cats. Pedigree analysis confirmed that the Dilution modification (Dm) observed in Caramel and Apricot cats is transmitted as an autosomal dominant trait.   Hair-analysis at the microscopic level revealed that Dm-hairs showed the same pigment aggregation as diluted hairs. There was no structural particularities for Dm-hairs compared to diluted-hairs.  

DNA analysis focused on a candidate gene that we have selected because it produces a dilution modification in mice that is equivalent to the feline Dm-gene effect. We have analyzed this gene in Dm-cats and in diluted-control cats and unfortunately we have not found any mutation in this gene in Dm-cats compared to control-cats. This gene was the only obvious candidate gene for the feline Dm coat-colour.  

However, three other genes that were recently characterized in the mouse may be involved in the feline Dm coat-colour. In the next months we will try to analyze these genes. For this purpose, we need additional DNA and hair samples from Caramel and Apricot cats as well as diluted (blue, lilac, fawn or cream) control-cats. All breeds are welcome. (Please find in PDF the sample-instruction-file).

UPDATE: Florence Bonvarlet has finished her veterinary thesis. You can download the manuscript (in French!) here Thanks to ultrastructural studies, they have found some structural particularities for Dm-hairs compared to diluted-hairs!