Test Detail

Recessive disease of the Dachshund (described in the smooth-haired miniature) that combines coat colour dilution with severe neurological deficit, analogous to human Griscelli syndrome type 1. Puppies show a light coat from birth and, in the first weeks, an inability to hold the head upright and to adopt stable postures. The progression is severe and leads to early euthanasia. It is distinct from the isolated 'd' colour dilution due to MLPH, which is not associated with neurological signs.

CDN due to MYO5A documented ONLY in the miniature Dachshund (one puppy, Christen 2021). Do NOT use for D-locus d1 of other breeds (use dlph/MLPH).

- In a puppy with diluted coat and neurological signs, suspect CDN and confirm by MYO5A genetic test if available\n- Do not mate two confirmed carriers: 25% risk of affected homozygotes\n- A carrier can be mated to a clear dog; offspring intended for breeding should be tested\n- Distinguish from 'd' colour dilution due to MLPH (isolated phenotype, without neurological signs)\n- Consider the rarity of the mutation: in most Dachshunds with diluted coat the cause will be MLPH, not MYO5A

The main differential diagnosis is MLPH colour dilution (d1, d2, d3 alleles), which is NOT associated with neurological defects and predisposes to colour dilution alopecia (CDA). CDN should be suspected when a diluted puppy presents ataxia or cervical hypotonia. Skin histology is similar to MLPH, but the neurological picture differs. MYO5A is an essential intracellular transporter in melanocytes and Purkinje dendrites; its loss explains the pigmentation and cerebellar dysfunction. In humans, Griscelli syndrome type 1 combines partial albinism with primary neurological deficit.

1. Christen M, de le Roi M, Jagannathan V, Becker K, Leeb T. MYO5A frameshift variant in a miniature Dachshund with coat color dilution and neurological defects resembling human Griscelli syndrome type 1. Genes (Basel) 12(10), 2021. PMID: 34680875
2. OMIA:001501-9615. Dilute coat color with neurological defects in Canis lupus familiaris. https://omia.org/OMIA001501/9615/