The term albinism describes a group of symptoms in which melanin synthesis (production of color pigments) is disturbed. There are two types of albinism:
Oculocutaneous Albinism (OCA) in which the eyes and skin are affected and Ocular Albinism (OA) in which only the eyes are affected. Depending on the extent to which the synthesis of the two corresponding color pigments (eumelanin and phaeomelanin) is disturbed, a distinction can be made between different forms. If no color pigments are formed, the dogs appear snow-white with pink-colored skin, a light-colored nose, light-colored paw pads, pink lips or "red eyes" (pink-colored or red irises).A certain mutation (the so-called caL mutation) can be observed in the French bulldog, the Lhaso Apso, the Pekingese and the Pomeranian, which causes albinism (autosomal recessive) and also when inherited from both parents suspected to be a trigger in other small, long-haired breeds.
Since the lack of pigmentation in the eyes can be associated with a certain photophobia (sensitivity to light), mating two carriers (carrier x carrier) should be avoided. To ensure this, it should be ensured that at least one parent animal is homozygous-free.Another mutation responsible for albinism (the so-called OCA2 mutation) was found in a Great Spitz mating, which causes less accumulation of color pigments in the skin, hair and eyes.The affected puppies of the examined Great Spitz showed a light brown coat, weakly pigmented lips and nose and blue eyes as characteristics instead of the expected black coat color. The light brown coat color darkened as the dogs aged and the blue eyes changed to a green colour.
(A) White mother and black father of the litter (B) Images of two affected puppies and one unaffected sibling on the left at one week old. (C,E) Affected dog GS103 with green eyes and a light nose aged 4 and 5.5 months respectively. (D, F) Affected dog GS104 at the age of 4 and 7 months.
Since the defect can be genetically traced back to a 1988 Großspitz male, which can be found in the pedigrees of both white and black Großspitz, it can be assumed that the mutation is already widespread in both colors of the Großspitz population is. So it is important to test both white and black and brown Greatspitz.It cannot be ruled out that OCA2 also exists in other pointed varieties.
The gene test for OCA2 should be obligatory for the breeding use of great Spitz.
Full study OCA2 splice site variant in German Spitz dogs with oculocutaneous albinism"Authors: Madleina Caduff, Anina Bauer, Vidhya Jagannathan, Tosso LeebPublished: 10/03/2017
Inheritance from OCA2
A monogenic autosomal recessive inheritance has been identified for OCA2. This means that only animals that carry the mutation on both gene copies show anomalies. The expression only exists if both father and mother carry the OCA2 mutation and both have passed this mutation on to their offspring.
Inheritance scheme
| | Parent 2 | | |
| Finding parents: | C/C = normal | C/cOCA2 = carrier | cOCA2/cOCA2 = affected |
Parent 1 | C/C = normal | 100% normal | 50% normal 50% carriers | 100% carrier |
| C/cOCA2 = carrier | 50% normal 50% carriers | 25% normal 50% carriers 25% affected | 50% carriers 50% affected |
| cOCA2/cOCA2 = affected | 100% carrier | 50% carriers 50% affected | 100% affected |
C/C (normal /clear/free/A) The animal does not carry an OCA2-causing mutation. It is homozygous for the normal copy of the gene. It will not get sick.
C/cOCA2 (carrier/carrier/B)The animal only carries the mutation responsible for OCA2 in one gene copy. It is a heterogeneous carrier of the mutation, but will not express OCA2. There is a 50% probability that he will pass the system on to his offspring.
cOCA2/cOCA2 (betreut/affected/C)The animal carries the mutation responsible for OCA2 on both gene copies. It is a homozygous carrier of the mutation and shows the anomalies of the OCA2. There is a 100% chance that the OCA2 trait will be passed on to the offspring.
Sources:
Texts: Barbara Tuschl & Janet Scheidig - www.spitz database.delabogen.com
Photo: Janet Scheidig