polysomy

On the other hand, having Y chromosome polysomy has other effects than masculinization.

A trisomy is a type of polysomy in which there are three instances of a particular chromosome, instead of the normal two.

Down syndrome in humans is an example of polysomy where affected individuals possess three copies (trisomy) of chromosome 21.

Polysomy is usually caused by non-disjunction (the failure of a pair of homologous chromosomes to separate) during meiosis, but may also be due to a translocation mutation.

Greater degrees of Y chromosome polysomy (having more than one extra copy of the Y chromosome in every cell, e.g., XYYY) are rare.

Polysomy is a condition in which an otherwise diploid organism has at least one more chromosome than normal, i.e. the number of a particular chromosome is not diploid - there may be three or more copies of the chromosome rather than the expected two copies.