Genetic test for the C locus (OCA4) in the Dobermann. It detects the 4,081 bp deletion in SLC45A2 associated with oculocutaneous albinism type 4 (OCA4), the white Doberman pinscher (WDP) phenotype; the actual colour is light cream, not pure white. Homozygotes show hypopigmentation of the skin, hair and ocular adnexa, blue irides with a tan periphery, pink nose and lips, hypopigmented retinal pigment epithelium and choroid, and photophobia; they also have a higher prevalence of cutaneous melanocytic neoplasms. Complementary to, not a substitute for, clinical and ophthalmological examination.

Applicable breed: Dobermann. The variant is linked to white Dobermann lines, but carriers have been identified among standard-coloured Dobermanns (2 in Winkler 2014); there are no reliable allele frequency estimates in the general breed population (limited data).

• Light cream coat from birth, with hypopigmented nose, lips and eyelid margins.
• Tan iris in the peripheral ciliary zone turning blue towards the pupil; non-pigmented leading edge of the nictitating membrane and cilia.
• Vertically oriented ovoid dyscoria and iris stromal thinning that transilluminates; hypopigmentation of the pectinate ligament, trabecular meshwork and retinal pigment epithelium.
• Photophobia in bright sunlight; no nystagmus was observed.
• Melanocytic neoplasms on skin and lips (12/20), eyelids (10/20) and iris (1/20) in the published series, versus 1/20 in standard-coloured Dobermanns; 8/8 in dogs over 5 years of age.

The first white Dobermann was registered with the American Kennel Club in 1976; all current WDPs descend from that female and breeding was based on intensive line breeding. International breed clubs recognise only black, blue, red and fawn coats, and white falls outside the standard. The autosomal recessive pattern was established from pedigrees and from the Doberman Pinscher Club of America study. In 2014, Winkler et al. identified the 4,081 bp deletion in SLC45A2 as the cause of the phenotype.

• Carrier × carrier: 25 % probability per offspring of an affected homozygote, 50 % carrier and 25 % clear.
• Carrier × clear: no affected offspring; 50 % will be carriers. If a carrier sire is used intensively, monitor its offspring so as not to increase the frequency.
• Do not breed from homozygotes: all their offspring will be carriers (none affected if the other parent is clear).
• Homozygotes show photophobia and a higher risk of melanocytic neoplasms; the decision to breed them should consider animal welfare and the breed standard.
• A negative result does not rule out other causes of a light coat or other albinism variants: the test detects only the Dobermann deletion.

• In homozygotes: ophthalmological examination (photophobia, iris, fundus) and periodic dermatological review of melanocytic lesions. Photoprotection is a prudent measure, although in the published series the distribution of lesions did not suggest a relationship with areas of greatest sun exposure.
• Differentiate OCA4 albinism from extreme white spotting (S/MITF locus) and other causes of a light coat; molecular diagnosis is what separates the variants (Brancalion 2022).
• In breeds other than the Dobermann, OCA4 may be due to other SLC45A2 variants not covered by this test.
• Winkler 2014 did not observe deafness or bleeding diathesis in the WDPs studied (clinical observation in 20 dogs, without BAER); extreme white spotting (MITF) can be associated with deafness.

1. Winkler 2014, A partial gene deletion of SLC45A2 causes oculocutaneous albinism in Doberman pinscher dogs (PMID 24647637); OMIA:001821-9615, variant 675.
2. Caduff 2017, A single base deletion in the SLC45A2 gene in a Bullmastiff with oculocutaneous albinism (PMID 28737247); OMIA:001821-9615, variant 795.
3. Wijesena 2015, A missense mutation in SLC45A2 is associated with albinism in several small long haired dog breeds (PMID 25790827); OMIA:001821-9615, variant 92.
4. Brancalion 2022, Canine coat pigmentation genetics: a review (PMID 34751460).