First Cases of Marfan Syndrome Documented in Domestic Cats

The feline siblings displayed signs of the condition from an early age, characterized by unusually long limbs. As they matured, veterinary examinations uncovered additional abnormalities, including issues with their eyes and an enlarged aorta, the primary artery responsible for carrying blood from the heart. This prompted researchers to explore the possibility of Marfan syndrome, a connective tissue disorder primarily known in humans.

Marfan syndrome affects approximately one in 4,000 people and is linked to alterations in connective tissues throughout the body, including in the eyes, bones, ligaments, skin, and blood vessels. Until the cases of Gary and Shaggy, no instances had been documented in cats.

The research team, comprising experts from Cornell University’s College of Veterinary Medicine and Baker Institute for Animal Health, along with specialists from Ghent University in Belgium, the University of Pennsylvania, and the Schwarzman Animal Medical Center in New York City, conducted comprehensive veterinary examinations paired with genetic sequencing.

Their investigation revealed alterations in the FBN1 gene, which encodes for fibrillin-1, a vital protein for healthy connective tissue. Both cats had inherited two altered copies of this gene, one from each parent. This finding was noteworthy, as in humans, a single mutated copy of FBN1 can lead to Marfan syndrome, while two mutated copies are exceedingly rare.

The variant the cats possessed did not entirely halt the gene's function but instead affected the processing of its instructions while allowing for some normal activity. This partial functionality may account for why Gary and Shaggy reached adulthood despite having two altered gene copies. The study indicated that the genetic variant caused exon 22 to be skipped in many of the gene's transcripts, although a smaller amount of properly processed genetic material was still produced.

The researchers viewed this discovery as a significant advancement for veterinary diagnosis of the disorder. Dr. Jacquelyn Evans, the study’s senior author and an assistant professor at Cornell’s Baker Institute for Animal Health, stated that the findings could aid veterinarians in recognizing similar cases in the future and potentially lead to the development of genetic tests.

The research was published in Scientific Reports on September 19, in a study titled "A homozygous hypomorphic FBN1 splice region variant in domestic cats with Marfan syndrome." The cases underscore the importance of studying naturally occurring genetic disorders in animals to gain insights into conditions that affect humans.