The aetiology of the cat eye syndrome reconsidered.

Guanti, Ginevra

doi:10.1136/jmg.18.2.108

Cited by 34 publications

(11 citation statements)

References 68 publications

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“…This work demonstrates how DNA sequence dosage analysis can be used to study genetic disorders that are not readily amenable to standard cytogenetic analysis. IN CAT EYE SYNDROME (CES), A SMALL supernumerary chromosome is associated with various malformations, including ocular colobomata, anal and cardiac defects, and mental retardation (1)(2)(3). Each associated feature is relatively common and none is necessarily present in every instance of CES.…”

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Characterization of the Supernumerary Chromosome in Cat Eye Syndrome

McDermid

Duncan

Brasch

et al. 1986

Science

147

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Most individuals with cat eye syndrome (CES) have a supernumerary bisatellited chromosome which, on the basis of cytogenetic evidence, has been reported to originate from either chromosome 13 or 22. To resolve this question, a single-copy DNA probe, D22S9, was isolated and localized to 22q11 by in situ hybridization to metaphase chromosomes. The number of copies of this sequence was determined in CES patients by means of Southern blots and densitometry analysis of autoradiographs. In patients with the supernumerary chromosome, four copies were found, whereas in one patient with a duplication of part of chromosome 22, there were three copies. Therefore, the syndrome results from the presence of either three or four copies of DNA sequences from 22q11; there is no evidence that sequences from other chromosomes are involved. This work demonstrates how DNA sequence dosage analysis can be used to study genetic disorders that are not readily amenable to standard cytogenetic analysis.

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confidence: 99%

Characterization of the Supernumerary Chromosome in Cat Eye Syndrome

McDermid

Duncan

Brasch

et al. 1986

Science

147

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“…The chromosome region 22q11.2 has long been recognized as a hotspot for genomic rearrangement and related disorders, such as 22q11.2 deletion syndrome (DiGeorge syndrome/velocardiofacial syndrome, OMIM 188400/ OMIM 192430) [DiGeorge and Harley, 1965;Shprintzen et al, 1978], der (22) t(11; 22) syndrome (OMIM 609029) and cat-eye syndrome (OMIM 115470) [Guanti, 1981;Edelmann et al, 1999a]. Der (22) syndrome and cat-eye syndrome are rare conditions characterized by increased copy-number of the most centromeric part of 22q11 [Zackai and Emanuel, 1980;McDermid and Morrow, 2002], whereas the microdeletions of 22q11.2 occur more often, with an estimated frequency of 1 in 4,000-6,000 live births [Yamagishi, 2002;Botto et al, 2003].…”

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Sixteen New Cases Contributing to the Characterization of Patients with Distal 22q11.2 Microduplications

et al. 2010

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The chromosome region 22q11.2 has long been recognized to be susceptible to genomic rearrangement. More recently, this genomic instability has been shown to extend distally (involving LCR22E–H) to the commonly deleted/duplicated region. To date, 21 index cases with ‘distal’ 22q11.2 duplications have been reported. We report on the clinical and molecular characterization of 16 individuals with distal 22q11.2 duplications identified by DNA microarray analysis. Two of the individuals have been partly described previously. The clinical phenotype varied among the patients in this study, although the majority displayed various degrees of developmental delay and speech disturbances. Other clinical features included behavioral problems, hypotonia, and dysmorphic facial features. Notably, none of the patients was diagnosed with a congenital heart defect. We found a high degree of inherited duplications. Additional copy number changes of unclear clinical significance were identified in 5 of our patients, and it is possible that these may contribute to the phenotypic expression in these patients as has been suggested recently in a 2-hit ‘digenic’ model for 16p12.1 deletions. The varied phenotypic expression and incomplete penetrance observed for distal 22q11.2 duplications makes it exceedingly difficult to ascribe pathogenicity for these duplications. Given the observed enrichment of the duplication in patient samples versus healthy controls, it is likely that distal 22q11.2 duplications represent a susceptibility/risk locus for speech and mild developmental delay.

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“…The 22q11.2 region is particularly susceptible to meiotic chromosome rearrangements associated with genomic disorders including velo-cardio-facial syndrome/DiGeorge syndrome (VCFS/DGS MIM192430/MIM188400) (DiGeorge 1965;Shprintzen et al 1978); the reciprocal duplication, dup(22)(q11.2;q11.2) (Edelmann et al 1999a;Bergman and Blenow 2000;Ensenauer et al 2003); and cat-eye syndrome (CES; MIM 115470) (Guanti 1981). Unequal crossing-over events between LCRs on Chromosome 22q11.2 are responsible for these genomic disorders.…”

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Traffic of genetic information between segmental duplications flanking the typical 22q11.2 deletion in velo-cardio-facial syndrome/DiGeorge syndrome

et al. 2005

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Velo-cardio-facial syndrome/DiGeorge syndrome results from unequal crossing-over events between two 240-kb low-copy repeats termed LCR22 (LCR22-2 and LCR22-4) on Chromosome 22q11.2, comprised of modules, each of which are >99% identical in sequence. To delineate regions in the LCR22s that might contain hotspots for 22q11.2 rearrangements, we scanned the interval for increased rates of recombination with the hypothesis that these regions might be more prone to breakage. We generated an algorithm to detect sites of altered recombination by searching for single nucleotide polymorphic positions in BAC clones from different libraries mapped to LCR22-2 and LCR22-4. This method distinguishes single nucleotide polymorphisms from paralogous sequence variants and complex polymorphic positions. Sites of shared polymorphism are considered potential sites of gene conversion or double cross-over between the two LCR22s. We found an inverse correlation between regions of paralogous sequence variants that are unique to a given position within one LCR22 and clusters of shared polymorphic sites, suggesting that these clusters depict altered recombination and not remnants of ancestral single nucleotide polymorphisms. We postulate that most shared polymorphic sites are products of past transfers of DNA information between the LCR22s, suggesting that frequent traffic of genetic material may induce genomic instability in the two LCR22s. We also found that gaps up to 1.5 kb long can be transferred between LCR22s.

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The aetiology of the cat eye syndrome reconsidered.

Cited by 34 publications

References 68 publications

Characterization of the Supernumerary Chromosome in Cat Eye Syndrome

Characterization of the Supernumerary Chromosome in Cat Eye Syndrome

Sixteen New Cases Contributing to the Characterization of Patients with Distal 22q11.2 Microduplications

Traffic of genetic information between segmental duplications flanking the typical 22q11.2 deletion in velo-cardio-facial syndrome/DiGeorge syndrome

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