What are the genetic changes related to Simpson-Golabi-Behmel syndrome ?
Mutations in the GPC3 gene are responsible for some cases of Simpson-Golabi-Behmel syndrome. This gene provides instructions for making a protein called glypican 3, which is involved in the regulation of cell growth and division (cell proliferation). Researchers believe that the GPC3 protein can also cause certain cells to self-destruct (undergo apoptosis) when they are no longer needed, which can help establish the body's shape.  GPC3 mutations can delete part or all of the gene, or alter the structure of glypican 3. These mutations prevent the protein from performing its usual functions, which may contribute to an increased rate of cell growth and cell division starting before birth. It is unclear, however, how a shortage of functional glypican 3 causes overgrowth of the entire body and the other abnormalities characteristic of Simpson-Golabi-Behmel syndrome.  Some individuals with Simpson-Golabi-Behmel syndrome do not have identified mutations in the GPC3 gene. In these cases, the cause of the condition is unknown.