Color dilution and neurological defects (CDN)

In the breed Miniature Dachshund, a variant in the gene MYO5A gene has been found to cause Coat Colour Dilution and Neurological Defects (CDN) resembling the human Griscelli Syndrome Type I. An affected 4-weeks old puppy showed a diluted, light red coat colour. Despite normally developed external features, the puppy was unable to hold a normal prone position, fell on its side and rowed with the upper front legs. Furthermore, it was unable to maintain an upright head position or to coordinate head movements and hardly reacted to environmental stimuli. The histopathological findings were a multifocal accumulation of melanin and a deposition of clumped keratin in the follicular epithelium of haired skin. Due to the severity of symptoms, the puppy was euthanized. A frameshift mutation in the MYO5A gene could be identified, myosin VA- mediated transport plays a crucial role in neurons and the cerebellum and also in melanosome transport into growing hair shafts.