Some bodies grow differently. In Marfan syndrome, a mutation causes the body to produce too much of a protein called fibrillin, and the bones seem not to know when to stop.
The result has a name of its own: arachnodactyly. Fingers and limbs so long and slender that at first glance they could seem like they belong to another species, with a flexibility that defies any expectation of what a human body can bend without breaking. It affects 3 out of every 10,000 people, so you probably know someone—without realizing it—who lives with this.
But here is the twist no one sees coming: while the limbs stretch outward, the heart and spine silently bear that same pressure, weakening from within. What is striking on the outside is only half the story.
