Erythema multiforme

Definition

Cutis laxa (Latin for loose or lax skin) is a connective tissue disorder in which the skin lacks elasticity and hangs in loose folds.

Description

Cutis laxa is extremely rare; less than a few hundred cases worldwide have been described.

The several forms of cutis laxa are divided into primary cutis laxa, which is present from birth and is hereditary, secondary cutis laxa, which arises later in life and may be either hereditary, and acquired cutis laxa, which arises later in life and is not hereditary. Loose skin, the primary and most obvious symptom of these diseases, is caused by underlying defects in connective tissue structure, which also cause more serious internal problems in vocal cords, bones, cartilage, blood vessels, bladder, kidney, digestive system, and lungs. The loose skin is particularly obvious on the face, and children with the disorder look sad or mournful.

There are four genetic forms of the disease, with sex-linked, autosomal dominant, and two types of autosomal recessive inheritance. The recessive forms are the most common and are usually more sever than the other forms.

Causes & Symptoms

Sex-linked cutis laxa is caused by a defective gene on the X chromosome. In addition to loose skin, its symptoms are mild mental retardation, loose joints, bone abnormalities (like hooked nose, pigeon breast, and funnel breast), frequent loose stools, urinary tract blockages, and deficiencies in lysyl oxidase, an enzyme required for the formation of properly functioning connective tissue. (But the defective gene does not code for lysyl oxidase.)

Autosomal dominant cutis laxa is caused by a defective gene carried on an autosomal (not sex-linked) chromosome. Its symptoms are loose, hanging skin, missing elastic fibers, premature aging, and pulmonary emphysema. Only a few families are known with cutis laxa inherited as a dominant trait.

Autosomal recessive cutis laxa type 1 is caused by a defective gene on chromosome 5. Symptoms include emphysema; diverticula in the esophagus, duodenum, and bladder; lax and dislocated joints; tortuous arteries; hernias; lysyl oxidase deficiencies; and retarded growth.

Autosomal recessive cutis laxa type 2 is also inherited as a recessive trait. In addition to the loose skin, this form of the disease is characterized by bone abnormalities, the delayed joining of the cranial (skull) bones, hip dislocation, curvature of the spine, flat feet, and excessive tooth decay.

Acquired cutis laxa tends to follow (and may be caused by) severe illness characterized by fever, inflammation, and a severe skin rash (erythema multiforme); an injury to the nerves that control blood vessel dilation and contraction; or an autoimmune condition.

Diagnosis

The signs of cutis laxa are very obvious, and it is usually easy to diagnose by examining the skin. The determination of which form of cutis laxa is present is aided by information about the associated symptoms and by family histories.

Treatment

There is no effective cure for any of these disorders. Complications are treated by appropriate specialists, for example, cardiologists, gastroenterologists, rheumatologists, and dermatologists. Plastic surgery can be helpful for cosmetic purposes, but the skin may become loose again.

Prognosis

The prognosis for cutis laxa varies with the form of the disorder. The effects may be relatively mild with individuals living a fairly normal, full life, or the disease may be fatal.

Prevention

The inherited forms of cutis laxa are genetically determined and are not currently preventable. Genetic counseling can be helpful for anyone with a family history of cutis laxa. The cause of acquired cutis laxa is not known, so no preventive measures can be taken.

Key Terms

Autosomal

Refers to the 22 pairs (in humans) of chromosomes not involved with sex determination.

Connective tissue

Tissue that supports and binds other tissue; much of it occurs outside of cells (extra-cellular) and consists of fibrous webs of the polymers, elastin and collagen. Cutis laxa is associated with defects in these fibers.

Diverticula

Pouches in the walls of organs.

Dominant trait

A genetic trait where one copy of the gene is sufficient to yield an outward display of the trait; dominant genes mask the presence of recessive genes; dominant traits can be inherited from only one parent.

Duodenum

The uppermost part of the small intestine, about 10 in. long.

Esophagus

The tube connecting the throat to the stomach, about 10 in. long.

Funnel breast (also known as pectus excavatum)

A condition where there is a hollow depression in the lower part of the chest.

Gene

A portion of a DNA molecule that either codes for a protein or RNA molecule or has a regulatory function.

Lysyl oxidase

An enzyme required for the crosslinking of elastin and collagen molecules to form properly functioning connective tissue; present in relatively low levels in at least some forms of cutis laxa.

Pigeon breast (also known as pectus carinatum

A chest shape with a central projection resembling the keel of a boat.

Recessive trait

An inherited trait that is outwardly obvious only when two copies of the gene for that trait are present; an individual displaying a recessive trait must have inherited one copy of the defective gene from each parent.

Sex-linked

Refers to genes or traits carried on one of the sex chromosomes, usually the X.

Tortuous arteries

Arteries with many bends and twists.

X chromosome

One of the two types of sex chromosomes; females have two X chromosomes, while males have one X chromosome and one Y chromosome.

Further Reading

For Your Information

Books

• Pope, F. Michael. "Pseudoxanthoma Elasticum, Cutis Laxa, and Other Disorders of Elastic Tissue." In Emery and Rimoin's Principles and Practice of Medical Genetics, edited by David L. Rimoin, J. Michael Connor, and Reed E. Pyeritz. 3rd. ed. New York: Churchill Livingstone, 1998.

  Organizations

• British Coalition of Heritable Disorders of Connective Tissue. Rochester House, 5 Aldershot Road, Fleet, Hampshire GU13 9NG, United Kingdom. Phone: 01(252) 81-0472. Fax: 01(252) 81-0473.
• National Arthritis and Musculoskeletal and Skin Diseases Information Clearinghouse, National Institutes of Health. 1 AMS Circle, Bethesda, Maryland 20892-3675. (301) 495-4484.

  Other

• OMIM Homepage, Online Mendelian Inheritance in Man. Searchable Database. http://www3.ncbi.nlm.nih.gov/Omim/

Gale Encyclopedia of Medicine. Gale Research, 1999.