Fibrodysplasia Ossificans Progressiva: A Rare Disease That Turns The Body Into Bone


Fibrodysplasia ossificans progressiva (FOP) begins with very little warning. When children are born with FOP, they appear normal aside from a possibly characteristic malformation of the largest toe that tends to be pointed inwards and may be shorter. It is not until the child is somewhere between two and five years old that most of them begin to develop swelling on their scalp, heads, back, or their neck.

Some patients, such as twenty-four-year-old Erin Danzer, are able to prevent the rapid progression of FOP with careful management. Erin contributed to a recent Newsweek article saying that she is grateful that her FOP disorder was discovered in its early stages.

Erin’s parents kept careful watch on her activities. Although she was unable to participate in sports, her discipline delayed the usual deformities that are caused by FOP. Until she turned 19, Erin was able to walk and sometimes even jog.

After a FOP flare-up at the age of nineteen, Erin was unable to walk unaided. Until that time, Erin did not believe there was an urgency to acknowledge her disability to others. But now her disability was obvious and she was unable to hide it. She no longer felt “normal.” Erin says the flareup that lasted two years took away her independence. She says it was the worst period of her life.

Frederick Kaplan M.D., Orthopedic Research Professor at the Perelman School in Pennsylvania, explained to Newsweek that FOP progresses rapidly in adolescence. At thirty years of age, the majority of patients are almost completely immobilized by the sheets of extra bone.

Dr. Kaplan estimates that so far he has visited about ninety percent of all FOP patients (N. 1000) in the world.

FOP is an aggressive disorder that transforms connective tissue and muscle into sheets and plates of bone.

The doctor said that most flare-ups tend to be spontaneous. Some are caused by injury, intramuscular injections, or biopsies. Even the immune system is suspected of being a trigger.

Internal Organs

FOP does not directly affect internal organs. However, the compression against the chest wall prevents it from expanding, eventually causing heart failure.

Dr. Kaplan says that the estimated life span for FOP patients is about age fifty-six.

But Erin could not be deterred. Within the last five years, she started a new job and improved her social life. Erin learned how to compensate for her disability by approaching daily activities differently.

The flareup even caused a problem with her jaw and she now has to rely on smoothies, protein shakes, and soft food.

Erin will occasionally get new flareups that are severe enough to cause her to lose more of her mobility. She approaches each one as they occur, taking one day at a time, and appreciates “good days.”

She finds her involvement with the FOP community, reaching out to other FOP patients, and fundraising especially rewarding.

Looking Forward

Professor Kaplan said that about sixteen biotechnology and pharmaceutical companies have shown an interest in drug development for investigation in clinical trials.

The discovery of the ACVR-1 gene mutation in 2006 has been an incentive for companies to develop a treatment. At least six trials for adults are being conducted at this time.

Dr. Kaplan points to a new era of clinical trials investigating small molecules that can inhibit extra bone. If the trials are successful, they can lead to the treatment of more common conditions such as joint and hip deterioration.


Rose Duesterwald

Rose Duesterwald

Rose became acquainted with Patient Worthy after her husband was diagnosed with Acute Myeloid Leukemia (AML) six years ago. During this period of partial remission, Rose researched investigational drugs to be prepared in the event of a relapse. Her husband died February 12, 2021 with a rare and unexplained occurrence of liver cancer possibly unrelated to AML.

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