Bends in human mitotic metaphase chromosomes revisited: 15q11-13 is the most frequent non-random autosomal bend in blood cultures

Abstract

We have investigated the preferential bending of some chromosome sites in blood cultures from normal and chromosomally abnormal subjects. A total of 2,262 centromeric and 2,718 non-centromeric bends were recorded, and 69 non-centromeric sites were found not to bend at random. 15q11-13 bending was found to be the most frequent non-random autosomal bend. Bends on chromosomes may be remnants of a folded chromosome state in the nucleus, and may facilitate the preferential involvement of some chromosomal bands in structural reorganizations such as the isoacentric fragments, or contribute to the high frequency of interstitial deletions and isodicentric inversion duplications involving the 15q11-13 region.

Characterization of six marker chromosomes by comparative genomic hybridization

“…FISH techniques confirmed an inv dup(15)(q11q13) in a girl, with mild autistic features, speech delay, motor skill, and object manipulation difficulties. The psu dic (15;15) was initially described by Van Dyke et al [1977], with repeating sequences (duplicons) and chromosome bends in 15q11‐q13 favoring meiotic exchanges [Lupski et al, 1996; Plaja et al, 2001; Pujana et al, 2002]. Generally, the patients' phenotype with inv dup (15)(q11‐q13/q14) of maternal origin, including Prader–Willi syndrome (PWS)/Angelman syndrome (AS) regions, comprises mental retardation, autism, facial dysmorphism, clinodactyly, and strabismus [Plattner et al, 1993; Wandstrat and Schwartz, 2000; Schinzel and Niedrist, 2001].…”

Fragile sites, chromosomal lesions, tandem repeats, and disease

“…X-chromosome bending was proposed to represent a remnant of the Barr body packaging from the previous interphase or, alternatively, a structural feature that helps to provide continuity to the Barr body from one interphase to the next ( Van Dyke et al, 1987 , 1986 ; Munn et al, 1991 ; Walker et al, 1991 ; Dietzel et al, 1998 ). Non-random bends in autosomes have also been described, with higher incidence with increasing length of the chromosomes, and thought to be associated with chromatin compaction as residue of a folded chromosome state in the interphase nucleus ( Flejter et al, 1984 ; Plaja et al, 2004 , 2001 ). More observations on different cell lines are necessary to obtain robust evidence that support a biological role of chromosomal bending and its dependance upon chromatin compaction and accessibility.…”