CAUSE

Fibrodysplasia Ossificans Progressiva is a very rare disorder, believed to occur in approximately 1 in 1 million people worldwide. Several hundred cases have been reported.

It is a genetic disease caused by a mutation of the gene ACVR1. This gene provides instructions for making a member of a protein family called bone morphogenetic protein (BMP) type I receptors. The ACVR1 protein is found in many tissues of the body including skeletal muscle and cartilage. It helps to control the growth and development of the bones and muscles, including the gradual replacement of cartilage by bone (ossification) that occurs in normal skeletal maturation from birth to young adulthood.

Studies show that variants in the ACVR1 gene disrupt mechanisms that control the receptor's activity. As a result, the receptor is turned on when it normally should not be. Too much receptor activity causes overgrowth of bone and cartilage, resulting in the signs and symptoms of fibrodysplasia ossificans progressiva.

Reference:

Fibrodysplasia ossificans progressive.” MedlinePlus Genetics. Last updated July 15, 2022. https://medlineplus.gov/genetics/condition/fibrodysplasia-ossificans-progressiva/#top