The Barcelona Zoo's most famous gorilla was an albino named Snowflake, who scientists now believe turned white by way of inbreeding.
Born wild in Equatorial Guinea, the male Western lowland gorilla was captured by villagers in 1966, and has since been known as the only white gorilla in the world.
Now, Spanish researchers have sequenced the gorilla's genome, revealing that Snowflake was probably the offspring of a pairing between an uncle and a niece.
Researchers led by Tomas Marques-Bonet of the Institut de Biologia Evolutiva at the University of Pompeu Fabra used frozen blood from the late ape to sequence the entire genome.
Comparing that sequence with those of humans and nonalbino gorillas, researchers narrowed the cause to the gene SLC45A2 --previously linked to albinism in mice, horses, chickens and a species of fish -- a mutant copy of which Snowflake received from both his parents.
Researchers then searched for stretches of DNA that were identical due to inbreeding. They found that 12 percent of the genes from Snowflake's mother and father matched, a percentage that indicates an uncle and niece as the most likely parentage, according to the study, published in the journal BMC Genomics.
Previous parentage studies in wild Western lowland gorillas have never found inbred mating, but the authors note that factors including "habitat loss, small population sizes and population fragmentation" may prevent the dispersal of breeding groups in some areas.
In humans, four genetic mutations are known to cause albinism, which is marked by white hair, pink skin, blue eyes, reduced vision and photophobia. Snowflake lived at Barcelona Zoo for 40 years until he died of skin cancer in 2003, brought on by his lack of pigmentation.