Catherine O'Hara was candid about being diagnosed with situs inversus in the years before her death. O'Hara learned later in life that she was born with the rare condition, when a person's major thoracic and abdominal organs are mirrored from their normal positions, per the National Institutes of Health. During a 2020 appearance on Virtual Happy Hour, O'Hara jokingly called herself a "freak" when she learned she had the condition more than two decades ago. "I love Western medicine, I just don't want to be a part of it. But I had to get a TB test when our youngest was in co-op nursery school and I went to my husband's doctor and he said let's do some baseline tests, and one of them was an EKG," she recalled. Catherine O'Hara Said She Felt 'Lucky' to Be Alive 2 Years Before Her Death O'Hara, who shared sons Luke and Matthew with husband Bo Welch, added that she was confused why the medical professional tried to use two different EKG machines before opting for a chest x-ray. "I was like, 'What is happening?' He calls us into his office and says 'You're the first one I've met!'" she explained, adding that it was the first time she had heard of situs inversus. "I'm one of seven kids and my parents were already gone and left the world by that time. Never heard anything about this." Catherine O'Hara Emma McIntyre/Getty Images In January 2026, O'Hara died at age 71. Creative Artists Agency, who represented O'Hara, confirmed her passing, sharing that the actress died at her home "following a brief illness." No additional details about her death were revealed at the time. Keep scrolling for everything to know about situs inversus: What Is Situs Inversus? Situs inversus is the condition where a person's chest and stomach organs have developed in a reversed position of normal anatomy, per the Cleveland Clinic. Most human organs develop in a left-right formation. With a person who has situs inversus, their organs are found in a right-left formation. The condition is caused by a genetic mutation and can be passed down from a person's parents. While a person with situs inversus' organs have developed in an unusual position, the body parts are typically still functionable. People with situs inversus tend to live normal lives. Is Situs Inversus Rare? Situs inversus is a very rare condition as roughly one in 10,000 people are diagnosed with it. What Are Symptoms of Situs Inversus? According to the Cleveland Clinic, there are no noticeable symptoms for situs inversus. In most cases, people with situs inversus learn about the condition while being treated for something else. Can Situs Inversus Be Treated? Situs inversus itself doesn't usually require treatment. However, it is important to inform a doctor if you have the condition if being treated for other ailments. What Did Catherine O'Hara Say About Having Situs Inversus? Catherine O'Hara shared that she had a specific kind of situs inversus called dextrocardia. Dextrocardia is the rare congenital condition where a person's heart is positioned on the right side of the chest instead of the left. "When the doctor told us that my heart was on the right side and my organs were flipped, my husband immediately said 'No, her head's on backwards,'" she joked in 2020. "Cheers to health!"