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Occipital horn syndrome (OHS), formerly considered a variant of Ehlers-Danlos syndrome, is an X-linked recessive connective tissue disorder. It is caused by a deficiency in the transport of the essential mineral copper, associated with mutations in the ATP7A gene. Only about 2/3 of children with OHS are thought to have genetically inherited the disorder; the other 1/3 do not have the disease in their family history. Since the disorder is X-linked recessive the disease affects more males. This is because they do not have a second X chromosome, unlike females, so essentially are lacking the 'backup' copy with proper function. Females are much more likely to be carriers only. For a female to be affected they must carry two defective X chromosomes, not just one.〔 (Horn Syndrome ), 9 August 2004.〕 The disorder is considered a milder variant of Menkes disease. == Characteristics == It is characterized by a deficiency in biliary copper excretion that causes deformations in the skeleton. These include projections on the back of the skull (parasagittal bone exostoses arising from the occipital bone—the so-called "occipital horns") as well as deformities of the elbow, radial head dislocation, hammer-shaped lateral ends of the clavicles, and abnormalities of the hips and pelvis.〔 OHS presents in early to middle childhood.〔 Children may present with features such as: * Normal/slightly delayed intelligence 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「occipital horn syndrome」の詳細全文を読む スポンサード リンク
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