This information is provided by the National Institutes of Health (NIH) Genetic and Rare Diseases Information Center (GARD).
Proteus syndrome is characterized by excessive growth of a part or portion of the body. The overgrowth is usually asymmetric, which means it affects the right and left sides of the body differently. Newborns with Proteus syndrome have few or no signs of the disorder. Overgrowth becomes apparent between the ages of 6 and 18 months and becomes more severe with age. It may result in differences in appearance and with time, an increased risk for blood clots and tumors. Some people with Proteus syndrome have neurological abnormalities, including intellectual disability, seizures, and vision loss, as well as distinctive facial features. Proteus syndrome is caused by a change (mutation) in the AKT1 gene. It is not inherited, but occurs as a random mutation in a body cell in a developing baby (fetus) early in pregnancy. The AKT1 gene mutation affects only a portion of the body cells. This is why only a portion of the body is affected and why individuals with Proteus syndrome can be very differently affected. Management of the condition often requires a team of specialists with knowledge of the wide array of features and complications of this condition.
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