The Van cat's odd-eyed trait results from the white spotting gene affecting melanocyte migration during development. Population studies show the trait reached 40% frequency through founder effects in isolation.
The genetics of an odd gaze
The striking appearance of a Turkish Van cat with one blue eye and one amber eye—a condition called heterochromia iridum—is the visible result of a specific genetic history. This trait is tied to the piebald or white spotting gene (S), a dominant gene that dictates the cat's signature "Van pattern," where color is mostly limited to the head and tail. During embryonic development, pigment-producing cells called melanocytes migrate from the neural crest to various parts of the body, including the skin, fur, and irises. The white spotting gene disrupts this migration.
When melanocytes fail to reach one of the eyes, that iris lacks melanin. The resulting blue color is not from a blue pigment but from the structural scattering of light, similar to the effect that makes the sky appear blue. The other eye, successfully colonized by melanocytes, develops its genetically determined color, typically amber or copper. This same gene is responsible for the cat's largely white body; about 80% of their coat is white due to the extensive expression of this partial leucism.
An isolated gene pool
The high frequency of heterochromia in the Van cat population is an example of a population genetics principle known as the "founder effect". The cats developed as a landrace for centuries in the geographically isolated region around Lake Van, the largest lake in Turkey. In this confined area, a small number of founding cats with the genes for white spotting and odd eyes established a new population.
This isolation and small founding population led to a loss of genetic variation compared to the larger global cat population, causing the alleles for these specific traits to become unusually common. While heterochromia is rare in most cat breeds, it became a common feature of the Van cat. The same developmental process that affects eye color can also influence hearing. The absence of melanocytes in the inner ear can lead to congenital deafness, often in the ear on the same side as the blue eye. Studies show that about 40% of odd-eyed white cats experience some degree of deafness. To preserve this unique genetic heritage, the Yüzüncü Yıl University established a dedicated Van Cat Research and Protection Center.
💡Fun Facts
Unlike most felines, Turkish Vans are famously nicknamed "swimming cats" due to their unusual affinity for water and their water-resistant, cashmere-like single coat.
The breed's distinctive coloration, with color restricted to the head and tail, is so well-known it's called the "Van pattern" in cat fancy.
In Turkey, the Van cat is considered a national treasure, and its export was historically restricted to protect the natural breed.
Local legend suggests the colored patch sometimes found on their shoulder is the "Mark of Allah," where God blessed the cat as it left Noah's Ark, which is said to have landed on nearby Mount Ararat.
The Van Cat Research Center (Van Kedi Evi) at Yüzüncü Yıl University is generally open to visitors daily, but hours can vary. It is best to confirm locally.
Admission
There is typically a small entrance fee.
Accessibility
The center is located on a modern university campus and is generally accessible. The terrain is flat.