I had never even heard of it until I read this article.
The article doesn't mention this, but from what I have read elsewhere, the idea that Lincoln had Marfan syndrome has been debunked. An article I read in a medical journal pointed out that one of the symptoms of Marfan syndrome is decreased physical strength. Lincoln displayed his great strength on a number of occasions, such as in wood-chopping demonstrations. The article also showed a cast of one of Lincoln's hands, which looked quite strong, without the thin fingers expected in Marfan syndrome.