‎Evolution‎

Imagine your muscles, ligaments and tendons slowly turning to bone, and you can do nothing as you become a living statue. This sounds like magic, but once again the truth is stranger than fiction. The skeleton you see belonged to a man named Harry Eastlack (1933-1973) who suffered from a condition called fibrodysplasia ossificans progressiva (FOP). The extra bone on his skeleton used to be tissue,

but because of a rare genetic mutation it ossified over the course of his life until he could only move his lips.

The first sign of FOP is a malformed big toe in newborns. Later, extra bone tends to appear in the neck, spine and shoulders. This bone production will then continue all over the body throughout the sufferer's life. Secondary issues can arise such as difficulties breathing or malnutrition due to problems eating or difficulty. Any injury causes the body to "heal" the area with more bone - the reason extra bone cannot be removed surgically. At the moment there is no definitive treatment, and any reports of successful drug treatments are anecdotal.

The cause of FOP appears to be a mutation in the ACVR1 gene, which controls production of a member of the bone morphogenetic protein (BMP) Type 1 receptors family. Under certain conditions, this mutated gene may change the shape of the receptor - preventing inhibitor proteins binding and leaving the receptor constantly activated. This prolonged activation causes an overgrowth of bone and the fusion of joints. But it's important to note we now know the cause - there is hope that in the future we will have a way to block the overactive receptor.

Photo credit: A.B. Shafritz et al., New Eng. J. Med. 1996, Massachusetts Medical Society (taken from HowStuffWorks' article on FOP).

http://ghr.nlm.nih.gov/condition/fibrodysplasia-ossificans-progressiva

http://www.ucsfbenioffchildrens.org/conditions/fibrodysplasia_ossificans_progressiva/

http://science.howstuffworks.com/environmental/life/human-biology/fop.htm