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An incident in chromosome separation during anaphase II (of meiosis II) called nondisjunction can result in sperm cells with an extra copy of the Y-chromosome. If one of these atypical sperm cells contributes to the genetic makeup of a child, the child will have an extra Y-chromosome in each of the body's cells. [23]
XYYY syndrome, also known as 48,XYYY, is a chromosomal disorder in which a male has two extra copies of the Y chromosome. The syndrome is exceptionally rare, with only twelve recorded cases. The presentation of the syndrome is heterogeneous, but appears to be more severe than its counterpart XYY syndrome.
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.
XXXYY syndrome is caused by two extra copies of the X chromosome alongside one extra copy of the Y chromosome, producing a total complement of 49 chromosomes rather than the usual 46. [1] Sex chromosome aneuploidies are the most frequent form of aneuploidy in humans. [ 9 ]
The tip of the Y chromosome contains the SRY gene and, during recombination, a translocation occurs in which the SRY gene becomes part of the X chromosome. [15] [26] If a fetus is conceived from a sperm cell with an X chromosome bearing the SRY gene, it will develop as a male despite not having a Y chromosome. This form of the condition is ...
While all human chromosomes contain repeats, more than 30 million letters of the Y chromosome — out of 62.5 million — are repetitive sequences, sometimes called satellite DNA or junk DNA.
The syndrome is defined by the presence of at least one extra X chromosome in addition to a Y chromosome, yielding a total of 47 or more chromosomes rather than the usual 46. Klinefelter syndrome occurs randomly. The extra X chromosome comes from the father and mother nearly equally.
The cells of those born male contain an X chromosome and a Y chromosome that make a pair and give instructions on which genes should be expressed in the body, the researchers said.