Oculocutaneous Albinism Lhasa Apso, Pekingese, Pomeranian Type (OCA)
Oculocutaneous Albinism Lhasa Apso, Pekingese, Pomeranian type is form of albinism, metabolic disorder affecting the melanin production, affecting these breeds. There are two forms of albinism: Oculocutaneous Albinism, which affects the eyes and the skin, and the ocular albinism (OA), where only the eyes are affected. The oculocutaneous albinism has been recorded in several breeds; Doberman pinscher, Leonberger, Rottweiler, Great Dane, German Spitz, Lhasa Apso, Pekingese, and Pomeranian, and in almost each breed, the disorder is caused by a different, breed-specific mutation. In several other species, including mice, humans, rabbits, cattle and cats, albinism is associated to mutation within tyrosinase gene.
OCA Characteristics and Symptoms
Oculocutaneous Albinism in Lhasa Apso, Pekingese and Pomeranian is displayed as hypopigmentation in skin, hair and eyes. Affected dogs have pale irises and pink noses and lips. Multiple reports show higher frequency of skin tumours and nevi, as well as photophobia and vision defects.
Oculocutaneous Albinism Lhasa Apso, Pekingese, Pomeranian Type is caused by a substitution mutation in SLC45A2 gene. The SLC45A2 gene codes for protein located in melanocytes. Exact function of this protein is not known, but it is likely involved in the production of melanin, by taking part in transport molecules crucial for the normal function of melanosomes.
Disorder is inherited in an autosomal recessive pattern. Healthy parents of an affected dog are obligate heterozygotes and therefore carry one mutant allele. Heterozygotes are carriers and show no symptoms. At conception, each cub has a 25% chance of being affected, a 50% chance of being an asymptomatic carrier, and a 25% chance of being unaffected and not a carrier.