Low copy repeats
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Low copy repeats (LCRs), also known as segmental duplications (SDs), are highly homologous sequence elements within the eukaryotic genome. They are typically 10–300 kb in length, and bear >95% sequence identity. Though rare in most mammals, LCRs comprise a large portion of the human genome due to a significant expansion during primate evolution.
Misalignment of LCRs during non-allelic homologous recombination (NAHR) is an important mechanism underlying the chromosomal microdeletion disorders as well as their reciprocal duplication partners. 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, hereditary neuropathy with liability to pressure palsies, Smith-Magenis syndrome, and Potocki-Lupski syndrome.
- ME Johnson. Primate Gene and Genome Evolution Driven by Segmental Duplication of Chromosome 16. PhD thesis, Case Western Reserve University, 2008.