What is the definition of Arthrogryposis Multiplex Congenita?
Arthrogryposis multiplex congenita (AMC) refers to the development of multiple joint contractures affecting two or more areas of the body prior to birth. A contracture occurs when a joint becomes permanently fixed in a bent or straightened position, which can impact the function and range of motion of the joint and may lead to muscle atrophy. AMC is not a specific diagnosis, but rather a physical symptom that can be associated with many different medical conditions. It is suspected that AMC is related to decreased fetal movement during development which can have a variety of different causes, including environmental factors (i.e. maternal illness, limited space), single gene changes (autosomal dominant, autosomal recessive, X-linked), chromosomal abnormalities and various syndromes. Treatment varies based on the signs and symptoms found in each person, but may include physical therapy, removable splints, exercise, and/or surgery.
What are the alternative names for Arthrogryposis Multiplex Congenita?
- Congenital multiple arthrogryposis
- Fibrous ankylosis of multiple joints
- Congenital arthromyodysplasia
- Myodystrophia fetalis deformans
- Guérin-Stern syndrome
- Otto syndrome
- Rocher-Sheldon syndrome
- Rossi syndrome
- Guerin-Stern syndrome
What are the causes for Arthrogryposis Multiplex Congenita?
The exact cause of arthrogryposis multiplex congenita (AMC) is not fully understood. AMC is thought to be related to decreased fetal movement during development, which can occur for a variety of reasons. When a joint is not moved for a period of time, extra connective tissue may grow around it, fixing it in place. Lack of joint movement also means that tendons connected to the joint are not stretched to their normal length, which can make normal joint movement difficult.
In general, there are four causes for decreased fetal movement before birth:
- Abnormal development of muscles. In most cases, the specific cause for this cannot be identified. Suspected causes include muscle diseases, maternal fever during pregnancy, and viruses which may damage the cells that transmit nerve impulses to the muscles.
- Insufficient room in the uterus for normal movement. For example, multiple fetuses may be present, the mother may lack normal amounts of amniotic fluid or there may be uterine structural abnormalities.
- Malformations of the central nervous system (the brain and/or spinal cord). In these cases, arthrogryposis is usually accompanied by a wide range of other symptoms.
- Tendons, bones, joints or joint linings may develop abnormally. For example, tendons may not be connected to the proper place in a joint.
AMC can be a component of numerous condition caused by environmental factors, single gene changes (autosomal dominant, autosomal recessive, X-linked), chromosomal abnormalities and various syndromes.
What are the symptoms for Arthrogryposis Multiplex Congenita?
Arthrogryposis multiplex congenita (AMC) refers to the development of multiple joint contractures affecting two or more areas of the body prior to birth. A contracture occurs when a joint becomes permanently fixed in a bent or straightened position, which can impact the function and range of motion of the joint. In some cases, only a few joints are affected and the range of motion may be nearly normal. In people who are severely affected, every joint in the body can be involved, including the jaw and back. Muscles of affected limbs may be atrophied or underdeveloped. Soft tissue webbing may develop over the affected joint.
AMC is not a specific diagnosis, but rather a physical symptom that can be found in many different medical conditions. The signs and symptoms associated with AMC can, therefore, vary greatly in range and severity depending on the underlying condition.
What is the outlook (prognosis) for Arthrogryposis Multiplex Congenita?
The long-term outlook (prognosis) for people with arthrogryposis multiplex congenita (AMC) depends on the severity of the condition, the underlying cause, and the affected person's response to therapy. The degree to which muscles and joints are affected varies significantly from person to person. AMC can be associated with a variety of conditions that are each characterized by unique symptoms.
In general, many people affected by AMC have a good prognosis. With physical therapy and other available treatments, substantial improvement in joint function and mobility is normally possible. Most people with AMC are of normal intelligence and are able to lead productive, independent lives as adults.
How is Arthrogryposis Multiplex Congenita diagnosed?
The Genetic Testing Registry (GTR) provides information about the genetic tests for this condition. The intended audience for GTR is health care providers and researchers. Patients and consumers with specific questions about a genetic test should contact a health care provider or a genetics professional.
Is Arthrogryposis Multiplex Congenita an inherited disorder?
Arthrogryposis multiplex congenita (AMC) is not inherited in most cases; however, a genetic cause can be identified in about 30% of affected people. It can be a component of many different genetic conditions, including those caused by a single gene change or a chromosomal abnormality, such as trisomy 18. Genetic conditions sometimes associated with AMC include some connective tissue disorders; muscle disorders such as muscular dystrophies or congenital myopathies; and certain mitochondrial disorders. Depending on the underlying genetic cause, it may be inherited in an autosomal recessive, autosomal dominant or X-linked manner. Some cases are thought to have multifactorial inheritance, which means that both genetic and environmental factors may play a role in causing the condition.