View source for Tisomy

A&nbsp;Trisomy &nbsp;is a type of polysomy inwhich instead of the usual two [[chromosomes|chromosomes]], there are three copies of a particular chromosome. A trisomy is a type of [[aneuploidy|aneuploidy]] (an abnormal number of chromosomes).&nbsp; 

The majority of human trisomies result in miscarriage, however there are a number of types that survive to birth. These include; [[Trisomy 13|Trisomy 13]] ([[Patau_Syndrome|Patau Syndrome]]), [[Trisomy_18|Trisomy 18]] ([[Edward's_Syndrome|Edward's syndrome]]) and [[Trisomy 21|Trisomy 21]] ([[Down Syndrome|Down Syndrome]]). Autosomal trisomy shows various levels of mental retardation and is associated with physical traits. 

Trisomy of [[Sex_chromosomes|sex chromosomes]] also occurs. XXX ([[Triple X syndrome|Triple X syndrome]]) and XXY ([[Klinefelter_syndrome|Klinefelter syndrome]]).