GPC4 and Simpson-Golabi-Behmel syndrome: In humans, mutations in GPC3 and GPC4 are associated with the development of the Simpson-Golabi-Behmel syndrome (SGBS), an X-linked inherited overgrowth syndrome characterized by a broad spectrum of clinical manifestations, such as congenital, facial and cardiac abnormalities, organomegaly, and reduced viability primarily in male patients (98).