Stone man syndrome therapy hope

Rachel Parkes has lost the use of her legs

Scientists say they have discovered the genetic trigger for a rare illness that turns muscle into bone.

Stone Man Syndrome, which strikes early in childhood and for which there is no cure, can imprison people with the condition in their own skeletons.

However, a team at the University of Pennsylvania say their work holds out promise of a treatment.

The study, published in the journal Nature Genetics, pinpoints a single gene as the cause of the condition.

The syndrome, known technically as fibrodysplasia ossificans progressiva (FOP) is one of the rarest diseases caused by a genetic mutation. It affects about one in 2 million people.

But the researchers hope their work will not only lead to a treatment for FOP, but also for a wide range of more common skeletal conditions.

In the longer term, it could also allow scientists to make bone in the laboratory.

Battling the disease

Rachel Parkes, 14, from Preston, is one of less than 40 people in the UK with the condition.

With the help of her outreach worker, Carrie Ann, she tries to lead as normal a life as possible.

But it's far from normal. Rachel's every move can make the disease worse. She used to sleep upstairs but even being carried was a risk.

As there is no current treatment all she can do is take steroids and extremely strong pain-killers.

She lost the use of her right leg last year and in January this year lost the use of her left leg.

The latest research offers her hope, where previously there was precious little.

Big hopes

Lead researcher Dr Frederick Kaplan said: "The discovery of the FOP gene is relevant to every condition that affects the formation of bone and every condition that effects the formation of the skeleton.

"Perhaps someday we will be able to harness the gene mutation that causes the renegade bone formation in FOP and make bone in a controlled way."

Dr Kaplan said that could potentially help patients who have severe osteoporosis, severe bone loss from trauma, fractures that fail to heal or congenital malformations of the spine and limbs.

The Pennsylvania team established that FOP was likely to be caused by a flaw in the system controlling the proteins responsible for bone formation and repair of the skeleton.

They were able to zero in on one specific gene, called ACVR1, and found that a single tiny mutation triggered the production of faulty proteins.

Professor Paul Wordsworth, an expert in rheumatology at Nuffield Orthopaedic Centre, in Oxford, also contributed to the research.

He said: "These things take many years to bring to fruition, but there are definitely ways in which you can expect to stop the new bone forming. It is the first glimmer of hope."