neocentromerer

Neocentromerer refers to a neocentromere, a chromosome region that gains centromere activity at an ectopic site. Unlike canonical centromeres, which are defined primarily by DNA sequence features such as alpha-satellite repeats, neocentromeres are defined by function and epigenetic marks. Centromere protein CENP-A-containing nucleosomes and kinetochore assembly establish their identity.

They typically arise after chromosomal rearrangements, deletions, or inactivation of the original centromere; their establishment involves recruitment of CENP-A and the assembly of the kinetochore, independent of underlying DNA sequence. They can be stable through mitosis and meiosis but may vary in stability.

Neocentromeres often occur in regions without canonical centromeric DNA, sometimes in gene-rich euchromatin; their exact DNA sequence is not predictive of centromere activity. They may be flanked by pericentromeric heterochromatin over time and can be detected by immunostaining of CENP-A and other centromere proteins or by fluorescence in situ hybridization to map the region.

Documented in humans and other species, including plants and animals, neocentromeres can accompany chromosomal rearrangements associated with developmental disorders, infertility, or miscarriages, though many are compatible with normal development when stable. They provide insight into the epigenetic specification of centromeres and genome plasticity.