Simpson-Golabi-Behmel syndrome is a condition that affects many parts of the body and occurs primarily in males. This condition is classified as an overgrowth syndrome, which means that affected infants are considerably larger than normal at birth (macrosomia) and continue to grow and gain weight at an unusual rate. The other signs and symptoms of Simpson-Golabi-Behmel syndrome vary widely. People with mild cases often live into adulthood.

Mutations in the GPC3 gene are the most common cause of Simpson-Golabi-Behmel syndrome. This gene provides instructions for making a protein called glypican 3, which blocks (inhibits) a developmental pathway called the hedgehog signaling pathway. This pathway is critical for cell growth and division (proliferation), cell specialization, and the normal shaping (patterning) of many parts of the body during embryonic development. Researchers believe that glypican 3 also helps establish the body's shape by causing certain cells to self-destruct (undergo apoptosis) when they are no longer needed.

The incidence of Simpson-Golabi-Behmel syndrome is unknown. At least 250 people worldwide have been diagnosed with this disorder.

This condition is inherited in an X-linked pattern. A condition is considered X-linked if the mutated gene that causes the disorder is located on the X chromosome, one of the two sex chromosomes in each cell. In males (who have only one X chromosome), one altered copy of the gene in each cell is sufficient to cause the condition. Because females have two copies of the X chromosome, one altered copy of the gene in each cell usually leads to less severe health problems in females than in males, or it may cause no signs or symptoms at all.

Published Date: July 01, 2017
Published By: National Institutes of Health