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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.
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.
In 1965 and 1966, researchers at the MRC Clinical & Population Cytogenetics Research Unit led by Dr. Court Brown at Western General Hospital in Edinburgh reported finding a much higher than expected nine XYY men (2.9%) averaging almost 6 ft. tall in a survey of 314 patients at the State Hospital for Scotland; seven of the nine XYY patients were ...
XXXYY syndrome, also known as 49 ... [20] and XYY [21] and tetrasomy X [22] in 1961. The 49,XXXYY karyotype was not reported again until 1974, highlighting the rarity ...
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]
XYY syndrome; XXXX syndrome; XXXXX syndrome This page was last edited on 7 February 2023, at 19:34 (UTC). Text is available under the Creative Commons Attribution ...
In 1959, five days after Jérôme Lejeune described the trisomy-21 [3] in Down syndrome, basing himself off Marthe Gautier's work, [4] Jacobs and John Strong described an additional X chromosome in male patients (the 47,XXY karyotype) [5] also known as Klinefelter syndrome, as Harry Klinefelter had already diagnosed the symptoms in 1942.