Since BWS has been associated with biallelic expression of insulin-like growth factor II (IGF-II), it has been proposed that GPC3 is a negative regulator of IGF-II.
A phenotypically related X-linked overgrowth syndrome, Simpson Golabi Behmel syndrome (SGBS), is caused by alterations in glypican-3 (GPC3), a molecule that may interact with the gene products identified to be important in generating the BWS phenotype, that is, IGF2 and p57KIP2.