Human acrocentric chromosome and their association with nucleolar organizer regions in down syndrome

Abstract

In human five chromosomal loci encode ~ 360 copies ribosomal genes are called nucleolar organizer regions (NORs). These are located on the short arm of the acrocentric chromo somes. The exact role of NORs is not known but it helps in the assembly of ribosomes during cell division (mitosis). In the present case study the Down syndrome case used as model of non - disjunction event because of having an extra copy of acrocentric chromosome become imperative to know the associations between acrocentric chromosomes and NORs sites associated transcriptional event. In this case high incidence of NORs expression (>60%/cell) were observed. However, this study of NORs explores the mechanism of transcription during neuronal differentiation causes "mental retardation" has not been documented earlier in the literature.