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Patau syndrome is a syndrome caused by a chromosomal abnormality, in which some or all of the cells of the body contain extra genetic material from chromosome 13. This can occur either because each cell contains a full extra copy of chromosome 13 (a disorder known as trisomy 13 or trisomy D), or because each cell contains an extra partial copy of the chromosome (i.e., Robertsonian translocation) or because of mosaic Patau syndrome. Full trisomy 13 is caused by nondisjunction of chromosomes during meiosis (the mosaic form is caused by nondisjunction during mitosis). The extra genetic material from chromosome 13 disrupts the normal course of development, causing multiple and complex organ defects. Like all nondisjunction conditions (such as Down syndrome and Edwards syndrome), the risk of this syndrome in the offspring increases with maternal age at pregnancy, with about 31 years being the average. Patau syndrome affects somewhere between 1 in 10,000 and 1 in 21,700 live births.〔(About.com > Patau Syndrome (Trisomy 13) ) From Krissi Danielsson. Updated June 10, 2009〕 ==Signs and symptoms== Of those fetuses that do survive to gestation and subsequent birth, common abnormalities may include: * Nervous system * * Intellectual disability and motor disorder * * Microcephaly * * Holoprosencephaly (failure of the forebrain to divide properly). * * Structural eye defects, including microphthalmia, Peters' anomaly, cataract, iris and/or fundus (coloboma), retinal dysplasia or retinal detachment, sensory nystagmus, cortical visual loss, and optic nerve hypoplasia * * Meningomyelocele (a spinal defect) * Musculoskeletal and cutaneous * * Polydactyly (extra digits) * * Cyclopia * * Proboscis * * Congenital trigger digits * * Low-set ears * * Prominent heel * * Deformed feet known as rocker-bottom feet * * Omphalocele (abdominal defect) * * Abnormal palm pattern * * Overlapping of fingers over thumb * * Cutis aplasia (missing portion of the skin/hair) * * Cleft palate * Urogenital * * Abnormal genitalia * * Kidney defects * Other * * Heart defects (ventricular septal defect) (Patent Ductus Arteriosus) * * Dextrocardia * * Single umbilical artery〔(【引用サイトリンク】title=Trisomy 13: MedlinePlus Medical Encyclopedia )〕 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「Patau syndrome」の詳細全文を読む スポンサード リンク
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