Arthrogryposis

Arthrogryposis, or arthrogryposis multiplex congenita (AMC), is a rare congenital disorder that is characterized by multiple joint contractures and can include muscle weakness and fibrosis. It is a non-progressive disease. The disease derives its name from Greek, literally meaning "curving of joints" (arthron, "joint"; grȳpōsis, late Latin form of late Greek grūpōsis, "hooking").

There are many known subgroups of AMC, with differing signs, symptoms, causes etc. In some cases, few joints may be affected and may have a nearly full range of motion. In the most common type of arthrogryposis, called amyoplasia, hands, wrists, elbows, shoulders, hips, feet and knees are affected. In the most severe types, nearly every joint is involved, including the jaw and back.

Frequently, the contractures are accompanied by muscle weakness, which further limits movement. AMC is typically symmetrical and involves all four extremities with some variation seen.

Classification
Some of the different types of AMC include:
 * Arthrogryposis multiplex due to muscular dystrophy.
 * Arthrogryposis ectodermal dysplasia other anomalies, also known as Cote Adamopoulos Pantelakis syndrome, Trichooculodermovertebral syndrome, TODV syndrome and Alves syndrome.
 * Arthrogryposis epileptic seizures migrational brain disorder.
 * Arthrogryposis IUGR thoracic dystrophy,also known as Van Bervliet syndrome.
 * Arthrogryposis like disorder, also known as Kuskokwim disease.
 * Arthrogryposis-like hand anomaly and sensorineural deafness.
 * Arthrogryposis multiplex congenita CNS calcification.
 * Arthrogryposis multiplex congenita distal (AMCD), with a large number of synonyms such as Arthrogryposis multiplex congenita, distal, x-linked (AMCX1) and Arthrogryposis spinal muscular atrophy
 * Gordon Syndrome, also known as Distal Arthrogryposis, Type 2A.
 * Arthrogryposis multiplex congenita, distal type 2B, also known as Freeman-Sheldon syndrome variant.
 * Arthrogryposis multiplex congenita neurogenic type (AMCN). This particular type of AMC has been linked to the AMCN gene on locus 5q35. Arthrogryposis multiplex congenita pulmonary hypoplasia, also with a large number of synonyms.
 * Arthrogryposis multiplex congenita whistling face, also known as Illum syndrome.
 * Arthrogryposis multiplex congenita, distal type 1 (AMCD1).
 * Arthrogryposis ophthalmoplegia retinopathy, also known as Oculomelic amyoplasia.
 * Arthrogryposis renal dysfunction cholestasis syndrome, also known as ARC Syndrome.

Signs and symptoms
There are numerous symptoms for this group of conditions. Some of the more common signs and symptoms are associated with the shoulder (internal rotation), elbow (extension and pronation), wrist (volar and ulnar), hand (fingers in fixed flexion and thumb-in-palm), hip (flexed, abducted and externally rotated, often dislocated), knee (flexion) and foot (clubfoot). Complications may include scoliosis, pulmonary hypoplasia, respiratory problems, growth retardation, midfacial hemangioma, facial and jaw variations, and abdominal hernias. Cognition and language are usually normal.

Causes
The cause is unknown, although several mechanisms have been suggested. This includes hyperthermia of the fetus, prenatal virus, fetal vascular compromise, septum of the uterus, decreased amniotic fluid, muscle and connective tissue developmental abnormalities. In general, the causes can be classified into extrinsic and intrinsic factors.

Extrinsic

 * There is insufficient room in the uterus for normal movement. For example, fetal crowding; the mother may lack a normal amount of amniotic fluid or have abnormally shaped uterine muscles.

Intrinsic

 * Neurological - Central nervous system and spinal cord are malformed. In these cases, a wide range of other conditions usually accompanies arthrogryposis.
 * Connective Tissue - Tendons, bones, joints or joint linings may develop abnormally. For example, tendons may not be connected to the proper place in a joint.

Research has shown that anything that prevents normal joint movement before birth can result in joint contractures. The joint itself may be normal. However, when a joint is not moved for a period of time, extra connective tissue tends to grow around it, fixing it in position. Lack of joint movement also means that tendons connecting to the joint are not stretched to their normal length; short tendons, in turn, make normal joint movement difficult. (This same kind of problem can develop after birth in joints that are immobilized for long periods of time in casts.)

The principal cause of AMC is believed to be decreased fetal movements (akinesia) caused by maternal or fetal abnormalities. It is associated with neurogenic and myopathic disorders. It is believed that the neuropathic form of AMC involves a deterioration in the anterior horn cell leading to muscle weakness and fibrosis. In most cases, arthrogryposis is not a genetic condition and does not occur more than once in a family. In about 30% of the cases, a genetic cause can be identified. The risk of recurrence for these cases varies with the type of genetic disorder. There is a rare autosomal recessive form of the disease known to exist.

In May 2013, scientists at the Max Planck Institute for Molecular Genetics in Berlin reported they had found mutations of the zinc-finger gene ZC4H2 to be the cause of AMC and intellectual disability. The clinical picture is variable as the severity of the disease depends on the position of the mutated amino acid in the protein. If the substitution is in a position that plays an important role in the functioning of the protein, a so-called zinc-finger domain, the most severe form of the disease arises and the affected boys die in the early months or years after birth. Girls and women with a mutation in this gene or a complete loss of the gene on one of the two X chromosomes can also be affected. 

Diagnosis
To date, no prenatal diagnostic tools are available to test for the condition. Diagnosis is only used to rule out other causes. This is done by undertaking muscle biopsies, blood tests and general clinical findings rule out other disorders and provides evidence for AMC.

Treatment
While there is no reversal of this condition, individual quality of life can be greatly improved. As each person will respond differently, and will have different needs, a combination of therapies is beneficial. Physical therapy including stretching, strengthening, and mobility training are often provided to improve flexion and range of motion to increase mobility. Occupational therapy (may also include casting, splinting of affected joints) can include training in ADL and fine motor skills as well as addressing psychosocial and emotional implications of living with a disability. Since there is a variety of mobility impairments, individually tailored orthopaedic correction is often beneficial. Orthopedic surgery, which include osteotomy or external Ilizarov fixator, may be elected to correct severely affected joints and limbs and symptoms such as clubfoot, hernia repair and correction of unilateral hip dislocation, in cases where these surgeries improve quality of life. However, in most cases, the contractures would recur despite surgery. A surgery called Tendon Release is usually done to stretch out the tendon that makes most patients walk on their toes.

Prognosis


Individuals with AMC are aided by vigorous therapy and in some cases surgical intervention. This varies to some degree, depending on the severity of mobility reduction. AMC is not a progressive disorder. Typically these individuals have normal cognition and speech and therefore the potential for productive, rewarding, and independent lives.

Epidemiology
AMC is relatively rare occurring in 1 out of every 3,000 live births. Amyoplasia, characterized by fatty and fibrous tissue replacement of the limb muscles, is the most common form, at 43% of reported cases. The majority of individuals thrive, with a minority strongly affected by respiratory muscle involvement.

Affected people

 * Celestine Tate Harrington, a quadriplegic street musician who performed at the Atlantic City Boardwalk and author of the 1996 book, "Some Crawl and Never Walk."
 * Asta Philpot, an American-born man living in England, who was the protagonist of a BBC documentary about prostitution as a means of offering the chance of sexual experiences to people with disabilities.
 * Lee Pearson, British 11-time gold medal winner at the Paralympic games in dressage.
 * Nicholas Taylor, American 3-time Paralympic champion in Quad Tennis.
 * Sunny Taylor, an American painter and activist.
 * Prudence Mabhena, lead singer for the band "Liyana" and subject of the short documentary Music by Prudence, which won an Academy Award for Best Documentary (Short Subject) in 2009.
 * Luca "LazyLegz" Patuelli, A Canadian B-boy who has appeared on The Today Show, So You Think You Can Dance Canada, and America's Got Talent, and performed at the 2010 Winter Paralympics opening ceremony in Vancouver.
 * Randy Fitzgerald, A professional gamer who goes by the gamertag "N0M4D" plays only with his lips and chin.
 * Rion Paige, a contestant on season three of the U.S. version of The X Factor.