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Structure and evolution of the Smith-Magenis syndrome repeat gene clusters, SMS-REPs.

ABSTRACT: An approximately 4-Mb genomic segment on chromosome 17p11.2, commonly deleted in patients with the Smith-Magenis syndrome (SMS) and duplicated in patients with dup(17)(p11.2p11.2) syndrome, is flanked by large, complex low-copy repeats (LCRs), termed proximal and distal SMS-REP. A third copy, the middle SMS-REP, is located between them. SMS-REPs are believed to mediate nonallelic homologous recombination, resulting in both SMS deletions and reciprocal duplications. To delineate the genomic structure and evolutionary origin of SMS-REPs, we constructed a bacterial artificial chromosome/P1 artificial chromosome contig spanning the entire SMS region, including the SMS-REPs, determined its genomic sequence, and used fluorescence in situ hybridization to study the evolution of SMS-REP in several primate species. Our analysis shows that both the proximal SMS-REP (approximately 256 kb) and the distal copy (approximately 176 kb) are located in the same orientation and derived from a progenitor copy, whereas the middle SMS-REP (approximately 241 kb) is inverted and appears to have been derived from the proximal copy. The SMS-REP LCRs are highly homologous (>98%) and contain at least 14 genes/pseudogenes each. SMS-REPs are not present in mice and were duplicated after the divergence of New World monkeys from pre-monkeys approximately 40-65 million years ago. Our findings potentially explain why the vast majority of SMS deletions and dup(17)(p11.2p11.2) occur at proximal and distal SMS-REPs and further support previous observations that higher-order genomic architecture involving LCRs arose recently during primate speciation and may predispose the human genome to both meiotic and mitotic rearrangements.

SUBMITTER: Park SS

PROVIDER: S-EPMC186597 | biostudies-literature | 2002 May

REPOSITORIES: biostudies-literature

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Structure and evolution of the Smith-Magenis syndrome repeat gene clusters, SMS-REPs.

Park Sung-Sup SS Stankiewicz Paweł P Bi Weimin W Shaw Christine C Lehoczky Jessica J Dewar Ken K Birren Bruce B Lupski James R JR

Genome research 20020501 5

An approximately 4-Mb genomic segment on chromosome 17p11.2, commonly deleted in patients with the Smith-Magenis syndrome (SMS) and duplicated in patients with dup(17)(p11.2p11.2) syndrome, is flanked by large, complex low-copy repeats (LCRs), termed proximal and distal SMS-REP. A third copy, the middle SMS-REP, is located between them. SMS-REPs are believed to mediate nonallelic homologous recombination, resulting in both SMS deletions and reciprocal duplications. To delineate the genomic struc ...[more]

PMID: 11997339

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Project description:Smith-Magenis syndrome (SMS0) is a complex and rare genetic multisystem disorder characterized by a variable pattern of cognitive deficits accompanied by a1 distinctive behavioral phenotype. SMS is characterized by subtle facial dysmorphology, short stature, sleep disturbances, and neurobehavioral abnormalities. Little is known about the manifestation of his unique case among Arab population and its strategic treatment.This study comes to present a case of SMS in an Arab newborn male who was born in spontaneous delivery on June 29, 2015, with tachypnea, tracheomalacia, and mild hypotonia. The newborn was admitted on the Neonatal Intensive Care Unit (NICU), and various laboratory examinations and clinical examinations were performed.Throughout his hospitalization, feeding difficulties appeared and thus a peripheral venous catheter was inserted in the left leg.After 22 days of follow-up and hospitalizations, the patient status improved and he was discharged with recommendations to be in follow up in pediatric outpatient clinic.However, notwithstanding the different investigations, intermittent tachypnea continued at a rate of 72 to 77?breaths/min. Search for diagnosis begin intensively owing to persistence of tachypnia, mild hypotonia, feeding difficulties, sleep disturbances, and mild dysmorphic facial features. Suspicions of genetic abnormalities were considered and blood samples were sent for chromosome analysis and for fluorescent in situ hybridization (FISH) testing.The genetic results revealed the following: cytogenetic findings: 46, XY, del(17)(p11.2) and the FISH results: del(17)(p11.2p11.2) (D17S29). The chromosome diagnosis revealed an interstitial deletion of 17p11.2 and the diagnosis of the SMS was confirmed.Accurate clinical diagnosis, therapeutic assessments and a holistic management plans, including multidiscipline therapeutic strategies, periodic neuro-developmental assessments, and an early intervention programs, are recommended.However, cytogenetic analysis or FISH using an RAI1-specific probe is the most frequently used technique for DS. Sleep and behavioral disturbances treatment include a combination of the daytime dose of acebutolol with an evening oral dose of melatonin. Melatonin as chronobiotic, antioxidant, and analgesic agent showed to be effective in different primary sleep disorders and in those associated with neurobehavioral disorders. Based on the beneficial effect of melatonin, it will be useful to use serum levels of melatonin as a follow-up test.

Dataset Information

Structure and evolution of the Smith-Magenis syndrome repeat gene clusters, SMS-REPs.

Publications

Structure and evolution of the Smith-Magenis syndrome repeat gene clusters, SMS-REPs.

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