Two domestic cat brothers, Gary and Shaggy, have become the first documented cats diagnosed with Marfan syndrome, a rare genetic disorder that affects connective tissue, after researchers linked their unusual physical symptoms to changes in the FBN1 gene.
The cats showed signs of the condition from an early age, including unusually long limbs. As they grew, veterinarians also found abnormalities in their eyes and an enlarged aorta, the main artery that carries blood away from the heart.
The unusual combination of symptoms prompted researchers to investigate whether the brothers had Marfan syndrome, a disorder more commonly recognized in humans.
Marfan syndrome affects about 1 in 4,000 people and can affect connective tissue in the eyes, bones, ligaments, skin and blood vessels. Until Gary and Shaggy were studied, the disorder had not been documented in domestic cats.
Researchers from Cornell University’s College of Veterinary Medicine and the Baker Institute for Animal Health worked with specialists from Ghent University in Belgium, the University of Pennsylvania and the Schwarzman Animal Medical Center in New York City, conducted detailed veterinary examinations and genetic testing to determine what was causing the cats symptoms.
Their analysis provides instructions for making fibrillin-1, a protein that helps maintain healthy connective tissue.
Both cats had two altered copies of the gene one inherited from each parent. The discovery was especially unusual because a single altered copy of the FBN1 gene can cause Marfan syndrome in humans.
Having two altered copies is extremely rare. Researchers found that the cats specific genetic variant did not completely shut down the FBN1 gene. Instead, it interfered with the way the gene’s instructions were processed while allowing some normal function to continue.
That remaining function may help explain why Gary and Shaggy survived into adulthood despite carrying two altered copies of the gene.
The study found that the genetic change caused exon 22 to be skipped in a large portion of the gene’s genetic messages. However, a smaller amount of normally processed genetic material was still produced.
Researchers said the discovery could help veterinarians identify similar cases in other cats and could eventually support the development of genetic tests for the condition.
Researchers said the cases also offer an opportunity to study naturally occurring genetic disorders in animals and gain comparative insights into diseases that affect humans.
