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XYY syndrome, also known as Jacobs syndrome, is an aneuploid genetic condition in which a male has an extra Y chromosome. [1] There are usually few symptoms. [2] These may include being taller than average and an increased risk of learning disabilities. [1] [2] The person is generally otherwise normal, including typical rates of fertility. [1]
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.
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. [14] [34] [35]
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.
Though a 48-chromosome complement involving the autosomes would be unsurvivable, 49,XXXYY and other high-level sex chromosome aneuploidies, such as tetrasomy X, pentasomy X, XYYY syndrome, XYYYY syndrome, and XXXXY syndrome, are survivable with relatively mild phenotypes due to the paucity of genes vital to basic development on the sex chromosomes.
XYYYY syndrome, also known as 49,XYYYY, is an exceptionally rare chromosomal disorder in which a male human has three additional copies of the Y chromosome. Only seven non- mosaic cases of the disorder have ever been recorded in the medical literature, as well as five mosaic cases, of which two had more 48,XYYY than 49,XYYYY cells. [ 1 ]
47, XYY syndrome (simply known as XYY syndrome) is caused by the presence of a single extra copy of the Y chromosome in each of a male's cells. 47, XYY males have one X chromosome and two Y chromosomes, for a total of 47 chromosomes per cell.
In 2005, researchers found a connection between expressive language delay and a genetic abnormality: a duplicate set of the same genes that are missing in individuals with Williams-Beuren syndrome. Also so called XYY syndrome can often cause speech delay. [39] Twins. Being a twin increases the chance of speech and language delays.