Marfan syndrome is a disorder that affects connective tissue. Connective tissues are proteins that support skin, bones, blood vessels, and other organs. One of these proteins is fibrillin. A problem with the fibrillin gene causes Marfan syndrome. Marfan syndrome can be mild to severe, and the symptoms can vary. People with Marfan syndrome are often very tall, thin, and loose jointed.
Marfan syndrome: Arachnodactyly positive thumb sign (entire thumbnail protrudes beyond ulnar border of hand. Positive wrist sign: thumb and fifth finger overlap when encircling the wrist. (Credit: John C S Dean, Eur J Hum Genet) #NPG