NCIt definition : A condition in which there is progressive heterotopic bone formation of the tendons
and muscles.;
Alternative definition : NICHD: An autosomal recessive disorder of connective tissue caused by mutation(s)
in the ACVR1 gene, encoding activin receptor type-1. This condition is characterized
by congenital malformations of the great toes and progressive ossification of skeletal
muscle, fascia, tendons, and ligaments.;