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Simpson–Golabi–Behmel syndrome (SGBS), also called Bulldog syndrome, Sara Agers syndrome, Golabi–Rosen syndrome, Simpson dysmorphia syndrome (SDYS) or X-linked dysplasia gigantism syndrome (DGSX), is a rare inherited congenital disorder that can cause craniofacial, skeletal, cardiac, and renal abnormalities. The syndrome is inherited in an X-linked recessive fashion,〔 where males express the phenotype and females usually do not. Females that possess one copy of the mutation are considered to be carriers of the syndrome and may express varying degrees of the phenotype. There are two types of SGBS, each found on a different gene: SGBS is also considered to be an overgrowth syndrome (OGS). OGS is characterized by a 2-3 standard deviation increase in weight, height, or head circumference above the average for sex and age. One of the most noted features of OGS is the increased risk of neoplasms in certain OGSs. SGBS in particular has been found to have a 10% tumor predisposition frequency with 94% of cases occurring in the abdominal region, most being malignant. It is common for tumors to be embryonal in type and appear before the age of 10. There are five different types of tumors that patients with SGBS might develop, all intra-abdominal: Wilms tumor, Hepatoblastoma, Hepatocarcinoma, Gonadoblastoma, and Neuroblastoma. The most common types of tumors developed in patients are the Wilms tumor and hepatoblastoma. ==Causes== Although not all causes of SGBS have been identified, one cause of SGBS type I is a mutation of the glypican-3 gene (GPC3) on the X chromosome locus q26.1. This particular gene is widely expressed, especially in tissues derived from the mesoderm during fetal development. The function of this gene is to produce a protein that acts as a cell surface receptor that binds to transcription factors. Binding of the transcription factors allows regulation of cellular responses to growth factors such as members of the hedgehog protein family. When large or small deletions and missense mutations occur along the GPC3 gene, GPC3 can no longer negatively regulate Hedgehog signaling during development, therefore increasing cell proliferation and the risk of developing cancer. Limb patterning and skeletal development may also go awry when GCP3 mutations inhibit regulations of responses to bone morphogenetic proteins, another type of growth factor. It has been suggested that SGBS type II may be caused by duplication of the GPC4 gene, which helps to regulate cell division and growth. Also, some patients diagnosed with SGBS do not have any GPC3 or GPC4 deletions or mutations. Possible explanations include promoter mutation or silencing of the GPC3 gene causing reduced expression in these patients. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Simpson–Golabi–Behmel syndrome」の詳細全文を読む スポンサード リンク
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