In 2006, Shore and Kaplan discovered the cause of FOP, publishing their findings as "A recurrent mutation in the BMP type I receptor ACVR1 causes inherited and sporadic fibrodysplasia ossificans progressiva".[6] The cause of the disease was traced to a single mutation in the activin A receptor, type I gene.[7] After the discovery, Kaplan remarked, "It took our team of researchers and collaborators more than 15 years of diligent effort to unravel the genetic cause of FOP, which had been shrouded in mystery for so long."[3]