Proteus Syndrome - Background

Proteus Syndrome

Background

Proteus syndrome is an extremely rare overgrowth syndrome thought to affect fewer than 500 individuals in the developed world. It is characterized by the progressive and abnormal growth of body tissues, including skin, bones, fatty tissues and blood vessels. Physicians named the condition for the Greek god who could transform his shape.

The most famous case of what some suggest could be Proteus syndrome is that of Joseph Merrick, known as the Elephant Man. Merrick gained celebrity - and for a time earned his livelihood in England and Europe - by being displayed in human novelty exhibitions as the Elephant Man. He died in 1890 at the age of 27 in London Hospital, now the Royal London Hospital, where he resided at the end of his life. Merrick's life has been portrayed on stage, and in a 1980 Hollywood movie titled "The Elephant Man."

Medical literature through the 20th century contains other descriptions of the disorder. Canadian-based geneticist Michael Cohen, Jr., DMD, Ph.D., first described the condition in 1979, and Hans Rudolf Wiedemann, a German pediatrician gave the disease its name in 1983.

In July of 2011, a team led by researchers at the National Institutes of Health discovered that the genetic cause of the condition is a point mutation - a single-letter misspelling in the DNA of the genetic code - in the AKT1 gene that causes sporadic tissue growth. Unlike inherited genetic disorders, the gene variant that causes Proteus syndrome occurs spontaneously in each affected individual after conception in just one cell of the developing embryo.

It is believed that the severity of the disease depends on when this spontaneous genetic change occurs in embryonic development. As the embryo grows and develops, only the descendants of the cell with the original AKT1 gene mutation display the hallmarks of the disease, leaving the individual with a mixture of normal and mutated cells, a condition called genetic mosaicism.

Newborns with Proteus syndrome almost always appear unaffected, and symptoms typically arise in the child's first two years of life. The mutation in AKT1 alters the ability of affected cells to regulate their own growth, causing some parts of the patient's body to grow to abnormal and even enormous sizes, while other parts of the body remain normal. The irregular overgrowth worsens with age and increases the susceptibility to tumors.

Besides overgrowth of limbs, Proteus syndrome also causes a variety of skin lesions and thickening of the soles of the feet. Some patients have neurological complications, such as mental retardation, seizures and vision loss. Blood vessel malformations are also associated with Proteus syndrome, and individuals with the condition are at greatly increased risk for deep vein thrombosis and pulmonary embolism.

Management of the Proteus syndrome requires a team of specialists with knowledge of the wide array of manifestations and complications of the disorder.