Cause

Genetic mutation

People with Fibrodysplasia Ossificans Progressiva (FOP) are born with mutations in the activin A receptor, type I (ACVR1) gene. Normally, this gene provides the body with instructions on how to produce the activin receptor type I protein, which is a member of a protein family called bone morphogenetic protein (BMP) type I receptors. The ACVR1 protein is present in many body tissues, including the skeletal muscles and cartilage. The protein helps regulate the growth and development of muscles and bones. It also helps control the gradual replacement of cartilage by bone that occurs when a person grows into an adult.

Random occurrence

Nearly all cases of FOP occur randomly and are not inherited. Instead, the genetic mutation randomly occurs during the development of the egg, sperm or embryo.

Inheritance

When FOP is inherited, it is passed down as an autosomal dominant trait— i.e. one copy of the mutated gene (from any of one parent) is enough for a child to develop the disorder. However, FOP is rarely inherited because most people with the disorder are unable to have children.

Source: wellness