What Is Stone Man Syndrome? Have you ever wondered how life will be if you are afraid of even small injuries?
The fear arises not from pain or bleeding after such injuries, but from the formation of bones when tissues like tendons, muscles, ligaments and other connective tissues are damaged.
Although a rare medical condition that occurs 1 in every 2 million individual, Stone man syndrome also known as ‘Fibrodysplasia Ossificans Progreesiva’ or FOP disease is a genetic disorder caused by a mutation in genes which allows injured connective tissues to be replaced with BONES !
This creates a new skeletal structure in people suffering from stone man disease. It characteristically starts from the bones of the neck and spreads downward to involve the sacral bones.
Few cases of this medical condition have been documented. Skeletons showing the ossification of connective tissues can be found in the Mütter Museum located in Philadelphia USA and in London. This is actually a part of Hunterian collection located in the Royal College of Surgeons.
Stone man syndrome becomes apparent early in life. New bones keep developing with age. Most patients with stone man syndrome survive into their 4th decade of life. They die from respiratory related symptoms.
Injuries sustained by trauma, sports, falls or even invasive medical procedures are harmful. They can trigger an intense inflammation of the muscles, tendons and ligaments. With healing, new bones are formed which replace the injured connective tissues.
Stone man syndrome is also referred to as FOP disease, Stone man disease, FOP syndrome, fibrodysplasia ossificans, and FOP disorder.
Stone man syndrome causes
Stone man syndrome is an autosomal dominant genetic disorder caused by a mutation in the ACVR1 gene. For most cases of this disorder, a spontaneous and new mutation occurs in an individual with no family history of the disease. However, few cases have been recorded with the gene being transmitted from one affected parent to the offspring.
In the inherited case of Stone man syndrome, only one altered allele (copy) of the gene from a parent is needed to express the disease. The ACVR1 gene acts as a modulator that controls the growth and proliferation of cells of the muscles, ligaments and other connective tissues. It specifically codes for a specific protein, the ‘morphogenetic protein (BMP) type 1 receptors’ that controls the normal ossification and maturation of skeletal bones.
Symptoms of Stone Man Syndrome are distinct and occur throughout life. Symptoms occur as a result of the replacement of connective tissues with bones. This extra-skeletal system accounts for the pain and change in physical statue associated with stone man syndrome. Common symptoms include:
The initial Tell-Tale sign of Stone Man Syndrome is the presence of malformed big toes. This is usually the first symptom of this disorder. It is also an important symptom because it helps physicians differentiate it from other similar musculoskeletal condition.
Difficulty in movement and joint stiffness caused by the fusion of joints and bones from the replacement of connective tissues with bones.
Difficulty in feeding from the fusion of the jaw bones. This affects the nutrition state of the patient leading to malnutrition and its related medical conditions. It also affects speech because of fusion of the joints of the jaw ‘lock jaw’.
Respiratory difficulty: with the formation of new bones in the rib cage, expansion of the rib cage becomes difficult and this leads to respiratory difficulties. Most patients with stone man syndrome die from respiratory failure and pneumonia.
Change in shape and posture: this is an obvious symptom of stone man syndrome caused by the fusion of bones and joints of the vertebrae. People with Stone Man Ssyndrome have a characteristic hump in the back, deviation of the back bone to the side, difficulty in movement and ability to perform certain task. By the 2nd or 3rd decade of life, most patients with stone man syndrome are usually completely bedridden.
Coping with Stone Man Syndrome
Till date, stone man syndrome has no cure. However, the administration of high dose corticosteroids may help reduce the intensity of muscle and connective tissue inflammation. This delays the formation of new bones from damaged connective tissues.
Since there is no cure for this disease, patients with Stone Man Syndrome are generally advised to prevent falls, trauma, engaging in contact sport, lifestyle and occupation modification which prevents injury to muscles and connective tissues.
Stone man syndrome also referred to as ‘Fibrodysplasia Ossificans Progreesiva’ is a genetic disorder characterized by the replacement of injured muscles, tendons, ligaments and other connective tissues with bones. These new bones lead to the formation of a new skeletal structure which is responsible for the physique and symptoms associated with stone man syndrome.
It is important to note that symptoms of stone man syndrome become apparent during childhood. However, by the 2nd decade of life, most patients with stone man syndrome are bed ridden. Life expectancy for Stone Man Syndrome can be about 40 years. Most death in stone man syndrome are as a result of respiratory failure and pneumonia.
Stone man syndrome is a genetic disorder caused by a mutation in genes that code for a specific protein that is responsible for the normal ossification of bones. Stone man syndrome can be inherited in an autosomal dominant pattern. Here the presence of a single defect allele in any of the parent is sufficient enough to cause disease and the defect gene can be transmitted to their offspring.
It is also important to note that most cases of Stone Man Syndrome are a result of new mutations occurring in individuals with no prior family history of the disease. Mutations can occur from exposure to ionizing radiation, chemical agents, drugs and infections. This exposure can occur in the womb or shortly after birth.
The affected gene in Stone Man Syndrome is the mutation in ACVR1 gene. This is located in the long arm of chromosome 2. The gene codes for Activin A receptor, type 1 protein or ‘morphogenetic protein (BMP) type 1 receptors’. This controls the rate of growth of bones and muscles. The mutation causes a change in the nature of the receptors, disrupting its specific function.
ACVR1 gene controls the ossification process of the body whereby cartilages are replaced by bones. At birth, most structures of the skeletal system are made up of cartilages and these cartilages are gradually replaced by matured bones during growth. This coordinated process is controlled by the ACVR1 gene. This is seen in skeletal maturation that begins during childhood.
Specifically, patients with Stone Man Syndrome have a genetic defect referred to as a ‘point mutation’ where an amino acid histidine is replaced with arginine at position 206 of the ACVR protein . This point mutation distorts the nature or the protein coded by this gene.
With the mutation in patients with stone man syndrome, there is a constant activation of the gene with subsequent release of the defective proteins whenever there is muscle or connective tissue injuries precipitated by trauma or acute viral infections.
This leads to the deposition of bone cells at sites of injuries, overgrowth of bones and the fusion of joints and bones. This specific mutation accounts for most of the symptoms seen in stone man syndrome.
Currently, prenatal testing for children born with this defect is not done routinely. However, genetic studies are used to confirm the diagnosis of stone man syndrome which is usually apparent on clinical evaluation.
Stone man syndrome is a unique but rare genetic disorder with characteristic symptoms. Affected individuals begin to show symptoms from early childhood. Symptoms persist and gradually worsen as patients get older.
New bones are formed outside of the skeletal structure with fusion of joints. The body starts looking like a solid statue. This results in difficulty in movement, difficulty in speech and feeding, respiratory failure and death by the 4th decade of life.