Overview of Arthrogryposis Multiplex Congenita

Symptoms

The symptoms of arthrogryposis multiplex congenita or AMC include neurologic defects, muscle defects, connective tissue as well as skeletal defects and fetal crowding and constraint. Maternal neuromuscular diseases like myotonic dystrophy or myasthenia gravis are also seen in the child. If the mother has the disease it is seen in the children after birth. If it is contracted during pregnancy there is a chance that the child will not contract it. But if the mother had the disease prior to pregnancy, there will be a 99.9% chance the child will contract it as well due to placental semi-permable membranous structures.Clubfoot, ankles that bend inward, elbows that are bent outward and knees or shoulders that bend unnaturally are seen in small children who have AMC. Limited movements of joints or joints that do not have full range of movement are included in this disorder.

Causes

There are thought to be many causes leading to AMC. AMC is formed during the fetal period, from 8 weeks after conception (10 weeks gestation) to birth. Additional connective tissue grows around the affected joint, and this tissue fixes the joint into place, therefore limiting the range of movement. Tendons around the joint do not stretch to normal lengths, and movement with physical therapy after birth is hard. Muscle defects, vascular compromises, maternal sickness, fetal crowding and neurologic defects as well as connective tissue skeletal defects are all known causes of AMC.

Types of Arthrogryposis Multiplex Congenita

There are over 150 types of arthrogryposis multiplex congenita known. Amyoplasia is the most common type of AMC, and is called classical arthrogryposis. This is seen in about 1 of every 10,000 live births in the United States and covers 1/3 of all AMC births. This is seen as symmetric position of the limbs, where extended elbows and absent muscle tissues are found. Distal arthrogryposis is the second most common, and involves only hands. It is characterized by overlapping fingers, clenched fists or deviation of the fingers from the ulnar side. This is inherited through a dominant autosomal trait and has been found to come from the 9th chromosome.

Contractural arachnodactyly is the third most common form of AMC and is also known as Beals syndrome. These sufferers are normally thin, with a crumpled ear as well as joint contractures. This form of AMC is caused by a mutation with dominant inheritance of the fibrillin gene on chromosome 5. This disorder is seen as multiple contractures with very long and thin toes and fingers that show arachnodactyly.

Other forms include popliteal pterygium which causes cleft lips, antecubial pterygium that is seen only in elbows, lethal popliteal pterygium where the facial cleft is seen with syndactyly of hands and feet and genital skin anomalies.

Resources

MedicineNet.com from the publication Definition of Arthrogryposis multiplex congenita (AMC) Last reviewed 11/29/2000

Global-Help.org from the publication Arthrogryposis