Ehlers-Danlos Syndrome: The Mutated Genes That Cause the Symptoms of Ehlers-Danlos Syndrome

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Collagen Defects

Connective tissue provides strength and support to many of the body’s organs, ligaments, and muscles, and collagen is a protein which acts like a glue, adding firmness, strength, structure, and elasticity to connective tissue. It makes up about a quarter of the amount of proteins in the human body.

There are six types of Ehlers-Danlos syndrome and they are all caused by faults with, or reduced amounts of different forms of collagen. Typical symptoms affect the joints and the skin.

Symptoms of Ehlers-Danlos Syndrome

The symptoms of Ehlers-Danlos syndrome vary widely and can range from mild to life-threatening. At the time of writing (August 2009) there is no known cure; treatment is given to manage the symptoms as best as possible. The symptoms include:-

Joints - loose, over flexible joints that are more prone to frequent dislocations, strains, sprains, and fractures; joint pain and early onset of osteoarthritis. There is hypermobility of the joints, that is they extend beyond their normal range of motion.

Skin - fragile skin that tears and scars easily; slow wound healing and the skin is easily bruised.

Different Types of Ehlers-Danlos Syndrome

The six different types of Ehlers-Danlos syndrome, which are listed below, either follow an autosomal dominant or autosomal recessive pattern of inheritance. Autosomal dominant means that only one of the two copies of a faulty gene needs to be inherited for a person to contract the condition. Autosomal recessive means that both faulty copies have to be inherited for a person to be affected by the condition.

Hypermobility - the most common form of the disease. Hypermobility affects elbow and knee joints, and smaller joints in fingers and toes. Chronic joint pain is another symptom. Skin bruises easily. Hypermobility follows an autosomal dominant pattern of inheritance.

Classica****l - the skin is smooth and stretchy, and joints are hyperextensible, meaning they can sprain and dislocate easily. Hernias are another complication with this type of Ehlers-Danlos syndrome. Classical follows an autosomal dominant pattern of inheritance.

Vascular - this is the most serious form of the condition. Skin is translucent, veins can be seen, and there is extensive bruising. Joint hypermobilty is usually found in the digits, and what makes the vascular form so severe is that there could be arterial or organ rupture. Vascular follows an autosomal dominant pattern of inheritance.

Arthrochalasia - a rare type where congenital hip dislocation is the major complication. Other symptoms include easy bruising and severe joint hypermobility. Dislocations are common. Arthrochalasia follows an autosomal dominant pattern of inheritance.

Dermatosparaxis - another rare type. Symptoms include extremely fragile skin with easy bruising. Individuals may also experience large hernias. Dermatosparaxis follows an autosomal recessive pattern of inheritance.

Kyphoscoliosis - also a rare form of the condition. There is a general laxity of the joints, and eyes and skin are fragile. Individuals can lose the ability to walk by their second or third decade. Kyphoscoliosis follows an autosomal recessive pattern of inheritance.

Ehlers-Danlos Syndrome and Genetic Mutations

Mutations of the following genes contribute to the various different types of Ehlers-Danlos syndrome: - ADAMTS2, COL1A1, COL1A2, COL3A1, COL5A1, COL5A2, PLOD1, and TNXB.

COL1A1, COL1A2, COL3A1, COL5A1, COL5A2 all code for types of collagen protein.

ADAMTS2, PLOD1, and TNXB are genes that make proteins that interact with or help to process collagen.

Further Reading

Ehlers-Danlos National Foundation