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45,X/46,XY mosaicism, also known as X0/XY mosaicism and Mixed gonadal dysgenesis,〔 () "45,X/46,XY including Y chromosome rearrangements". (PDF) Rarechromo.org〕 is a rare disorder of sex development in humans associated with sex chromosome aneuploidy and mosaicism of the Y chromosome. This is called a mosaic karyotype because, like tiles in mosaic floors or walls, there is more than one type of cell. The clinical manifestations are highly variable, ranging from partial virilisation and ambiguous genitalia at birth, to patients with a completely male or female gonads. Most individuals with this karyotype have apparently normal male genitalia, and a minority with female genitalia, with a significant number of individuals showing genital abnormalities or intersex characteristics. A significantly higher than normal number of other developmental abnormalities are also found in individuals with X0/XY mosaicism.〔 Psychomotor development is normal. ==Signs and symptoms== Although similar in some ways to true hermaphroditism, the conditions can be distinguished histologically and by karyotyping. The observable characteristics (phenotype) of this condition are highly variable, ranging from gonadal dysgenesis in males, to Turner-like females and phenotypically normal males.〔 The phenotypical expression may be ambiguous, intersex, or male or female depending on the extent of the mosaicism. The most common presentation of 45,X/46,XY karyotype is phenotypically normal male, next being genital ambiguity. There is a range of chromosomal anomalies within 45,X/46,XY where the variations are very complex, and the actual result in living individuals is often not a simple picture.〔 Most patients with this karyotype are known to have abnormal gonadal histology and heights considerably below their genetic potential. High gonadotropin levels have been described in both male and female patients, as well as low levels of testosterone in male patients. Dosage loss of SHOX gene is commonly associated with short stature.〔(45,X/46,XY mixed gonadal dysgenesis ). ''Orfa.net''; August 2015.〕 Psychomotor development is normal. As the gonads may not be symmetrical, the development of the Müllerian duct and Wolffian duct may be asymmetrical, too. Because of the presence of dysgenetic gonadal tissue and Y chromosome material, there is a high risk of the development of a gonadoblastoma.〔 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「45,X/46,XY mosaicism」の詳細全文を読む スポンサード リンク
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