Double Y syndrome (XYY syndrome) is caused by a random error in cell division.
Here's a more detailed explanation:
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Normal Chromosome Arrangement: Typically, males have one X and one Y chromosome (XY).
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The Extra Y Chromosome: In XYY syndrome, a male has an extra Y chromosome, resulting in an XYY chromosomal arrangement. This is not inherited from either parent.
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Random Cell Division Error: The extra Y chromosome arises during either the formation of sperm cells (spermatogenesis) in the father or, less commonly, during the formation of the egg cell (oogenesis) in the mother or early development of the embryo after fertilization.
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Non-Disjunction: The most common mechanism is called nondisjunction. This means that during cell division, the Y chromosomes in the sperm cell (or, less commonly, the sex chromosomes in the egg cell) do not separate properly. This results in a sperm cell (or egg cell) with an extra Y chromosome. If this sperm cell fertilizes a normal egg cell (or vice versa), the resulting offspring will have the XYY chromosome arrangement.
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Not Inherited: It's crucial to understand that XYY syndrome is not something parents cause or pass down through their genes. It's a spontaneous genetic event. Parents who have a child with XYY syndrome typically have normal chromosomes themselves. There is no increased risk of having another child with XYY syndrome.
In summary, Double Y syndrome arises due to a chance occurrence during cell division, leading to an extra Y chromosome in males.
