Characterization of Human Chromosomal Constitutive Heterochromatin

Heterochromatin of centromeric chromosome regions contains late replicating, largely repetitive DNA. It is suggested that heterochromatin participates in chromosome pairing, crossing-over and in chromosome disjunction control (1,3). Centromeric heterochromatin, a variety of heterochromatin, is a tightly packed form of DNA.Centromeric heterochromatin is a constituent in the formation ofactive centromeres in most higher-order organisms; the domain exists on both mitotic and interphase chromosomes. (4,5,6,8) Centromeric heterochromatin is usually formed on alpha satellite DNA in humans; however, there have been cases where centric heterochromatin and centromeres have formed on originally euchromatin domains lacking alpha satellite DNA; this usually happens as a result of a chromosome breakage event and the formed centromere is called a neocentromere.