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The syndrome is diagnosed in an increasing number of children prenatally by amniocentesis and chorionic villus sampling [24] in order to obtain a chromosome karyotype, where the abnormality can be observed. It is estimated that only 15–20% of children with 47,XYY syndrome are ever diagnosed. Of these, approximately 30% are diagnosed prenatally.
The presentation of XYYY syndrome is variable and at this time not entirely clear. As all known cases were diagnosed postnatally (after birth), and the similar XYY syndrome is known to have a milder phenotype in prenatally than postnatally diagnosed cases, it is suspected that many cases of XYYY syndrome may be mild or asymptomatic.
48,XXYY syndrome is a condition related to the X and Y chromosomes (the sex chromosomes). People normally have 46 chromosomes in each cell.Two of the 46 chromosomes, known as X and Y, are called sex chromosomes because they help determine whether a person will develop male or female sex characteristics.
Klinefelter syndrome is not an inherited condition. The extra X chromosome comes from the mother in approximately 50% of the cases. Maternal age is the only known risk factor. Women at 40 years have a four-times-higher risk of a child with Klinefelter syndrome than women aged 24 years. [15] [35] [36]
The Focus Foundation, located in Davidsonville, Maryland, is a research foundation dedicated to identifying and assisting families and children who have X and Y Chromosomal Variations (also called X & Y chromosomal variations), dyslexia and/or developmental coordination disorder.
The children with trisomy X and Klinefelter's had their karyotypes disclosed to their parents, but due to the then-present perception that XYY syndrome was associated with violent criminality, those diagnoses were hidden from the family. [56]
46,XX/46,XY chimeric or mosaic is associated with a wide spectrum of different physical presentations, with cases ranging from having a completely normal male or female phenotype [7] [8] [9] to some cases having ovotesticular syndrome. Due to this variation, genetic testing is the only way to reliably make a diagnosis.
XY complete gonadal dysgenesis, also known as Swyer syndrome, is a type of defect hypogonadism in a person whose karyotype is 46,XY. Though they typically have normal vulvas , [ 1 ] the person has underdeveloped gonads, fibrous tissue termed " streak gonads ", and if left untreated, will not experience puberty .