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verification. (March 2009) |
Low copy repeats (LCRs), also known as segmental duplications (SDs), are DNA sequences present in multiple locations within a genome that share high levels of sequence identity.
The repeats, or duplications, are typically 10–300 kb in length, and bear greater than 95% sequence identity. Though rare in most mammals, LCRs comprise a large portion of the human genome owing to a significant expansion during primate evolution. [1] In humans, chromosomes Y and 22 have the greatest proportion of SDs: 50.4% and 11.9% respectively. [2]
Misalignment of LCRs during non-allelic homologous recombination (NAHR) [3] is an important mechanism underlying the chromosomal microdeletion disorders as well as their reciprocal duplication partners. [4] Many LCRs are concentrated in "hotspots", such as the 17p11-12 region, 27% of which is composed of LCR sequence. NAHR and non-homologous end joining (NHEJ) within this region are responsible for a wide range of disorders, including Charcot–Marie–Tooth syndrome type 1A, [5] hereditary neuropathy with liability to pressure palsies, [5] Smith–Magenis syndrome, [6] and Potocki–Lupski syndrome. [3]
The two widely accepted methods for SD detection [7] are:
This article needs additional citations for
verification. (March 2009) |
Low copy repeats (LCRs), also known as segmental duplications (SDs), are DNA sequences present in multiple locations within a genome that share high levels of sequence identity.
The repeats, or duplications, are typically 10–300 kb in length, and bear greater than 95% sequence identity. Though rare in most mammals, LCRs comprise a large portion of the human genome owing to a significant expansion during primate evolution. [1] In humans, chromosomes Y and 22 have the greatest proportion of SDs: 50.4% and 11.9% respectively. [2]
Misalignment of LCRs during non-allelic homologous recombination (NAHR) [3] is an important mechanism underlying the chromosomal microdeletion disorders as well as their reciprocal duplication partners. [4] Many LCRs are concentrated in "hotspots", such as the 17p11-12 region, 27% of which is composed of LCR sequence. NAHR and non-homologous end joining (NHEJ) within this region are responsible for a wide range of disorders, including Charcot–Marie–Tooth syndrome type 1A, [5] hereditary neuropathy with liability to pressure palsies, [5] Smith–Magenis syndrome, [6] and Potocki–Lupski syndrome. [3]
The two widely accepted methods for SD detection [7] are: