The evaluation of 15q proximal duplications by FISH

Riordan, D.; Dawson, AJ

doi:10.1111/j.1399-0004.1998.tb03773.x

Cited by 16 publications

(3 citation statements)

References 17 publications

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“…Duplications, which do not contain the PWACR are usually familial, appear to be without clinical effect, and may be regarded as a polymorphism [Carelle‐Calmels et al, 2008]. The second category of duplications includes the PWACR, may be familial or de novo in origin and have been reported with variable clinical phenotypes [Browne et al, 1997; Riordan and Dawson, 1998; Gurrieri et al, 1999; Bolton et al, 2001]. The phenotypic expression is also dependent on the parental origin of the duplication with a more severe phenotypic effect in cases involving the maternally derived homologue (inherited from an affected mother or de novo derived from the maternal chromosome 15q).…”

Section: Discussionmentioning

confidence: 99%

“…Morphologic examination is usually normal [Mohandas et al, 1999; Mao et al, 2000; Boyar et al, 2001]. The phenotype–genotype correlations remain unclear, but it seems that the parental origin of the duplication as well as the presence or absence of the Prader–Willi/Angelman Critical region (PWACR) in the duplicated region play a major role in the clinical severity [Browne et al, 1997; Cook et al, 1997; Riordan and Dawson, 1998; Schroer et al, 1998; Bolton et al, 2001]. We report here on the clinical phenotype and genetic characterization of 12 members in a family positive for the duplication.…”

Section: Introductionmentioning

confidence: 99%

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Clinical and molecular characterization of a large family with an interstitial 15q11q13 duplication

Piard

Philippe

Marvier

et al. 2010

American J of Med Genetics Pt A

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The clinical significance of an interstitial duplication of chromosome 15q11q13 is still not well documented. This abnormality has been associated with autistic spectrum disorders (ASD) and varying degrees of mental retardation. The clinical variability appears to be influenced by the parental origin of the duplication. We present here the clinical evaluation and psychological assessment of the largest reported family with 12 carriers on three generations. Patients exhibit mental retardation, motor and visuo-motor skills impairments and adaptive functioning deficit without formal diagnosis of autism. There appeared to be evidence in the family of reduced penetrance in duplication of paternal origin. This familial 15q11q13 duplication was precisely investigated by cytogenetic and molecular techniques including fluorescence in situ hybridization (FISH), PCR analysis of microsatellite markers, array-comparative genomic hybridization analysis (Array-CGH) and semi-quantitative methylation-sensitive PCR. Results showed an inherited 15q11q13 duplication of maternal origin in 10 patients and of paternal origin in the remaining two. The size of the duplicated area was around 6 Mb with breakpoints in accordance with those previously reported. This report extends the clinical spectrum of the 15q11q13 duplication, and we recommend the investigation of 15q11q13 duplication not only in subjects with autistic spectrum disorder but also in patients with low normal intelligence and dyspraxia.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Clinical and molecular characterization of a large family with an interstitial 15q11q13 duplication

Piard

Philippe

Marvier

et al. 2010

American J of Med Genetics Pt A

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“…To date, almost all which include the PWASCR have demonstrated maternal inheritance with the exception of paternally derived idic(15) in a few patients in conjunction with maternal UPD, in which case the paternally derived idic(15) appeared to “rescue” the Prader–Willi phenotype to some extent [Saitoh et al, 2007]. Paternal inheritance of a small SMC 15 in the form of an idic(15) consisting of only satellite DNA and no unique sequence has been reported in a few patients and appears to be benign [Leana‐Cox et al, 1994; Riordan and Dawson, 1998]. Likewise, paternally inherited intrachromosomal duplications of the PWASCR have been described in normal individuals [Browne et al, 1997], furthering the evidence which suggests increased dosage of this region is only detrimental when inherited from the mother.…”

Section: Discussionmentioning

confidence: 99%

Partial hexasomy for the Prader–Willi–Angelman syndrome critical region due to a maternally inherited large supernumerary marker chromosome

Hoppman-Chaney

Dawson

Nguyen

et al. 2010

American J of Med Genetics Pt A

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Extra copies of the Prader-Willi-Angelman syndrome critical region (PWASCR) have been shown to have detrimental phenotypic effects depending on the parent of origin. Hexasomy for the PWASCR is rare; only 6 cases have been described to date. We report on a 15-year-old girl referred for developmental delay and seizures with a mosaic tricentric small marker chromosome (SMC) 15 identified by routine G-banding chromosome studies. C-banding and FISH confirmed the presence of three chromosome 15 centromeres as well as four copies of the PWASCR on the SMC in approximately 60% of interphase cells. Microsatellite genotyping documented maternal inheritance of the SMC, and methylation-sensitive multiplex ligation-dependent PCR amplification (MS-MLPA) showed that the extra copies of the PWASCR contained on the marker chromosome bear a methylation pattern similar to a normal maternal chromosome, implying maternal inheritance. These findings are consistent with the patient's phenotype as paternal inheritance of such a marker chromosome is thought to be benign. However, this patient's phenotype is the mildest described to date and may be a result of mosaicism for the SMC.

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Fluorescence in situ hybridization detectable mosaicism for Angelman syndrome with biparental methylation

et al. 2000

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We present a child with mild to moderate global developmental delay including severe speech impairment, inappropriate happy demeanor, wide-based gait, frequent ear infections with mild hearing loss, deep-set eyes, a wide mouth, widely-spaced teeth, normal head circumference, and no seizures. Results of peripheral blood lymphocyte chromosomal analysis with GTG banding were normal. However, fluorescence in situ hybridization (FISH) studies showed mosaicism for a deletion of probes (D15S10 and SNRPN) from the Angelman syndrome (AS) critical region with approximately 40% of peripheral lymphocytes having the deletion. The deleted chromosome 15 also showed centromeric duplication, which was detected with a D15Z1 probe [46,XX, dic(15)(pter-->q11.1::p11.2-->q11. 1::q13-->qter)]. The same duplication pattern was observed in 30% of the nuclei obtained from a buccal smear. Methylation studies using polymerase chain reaction with sodium bisulfite-treated DNA demonstrated a normal biparental methylation pattern. To the best of our knowledge, this is the first case with AS and a FISH detectable deletion in a mosaic pattern. We recommend FISH studies for the detection of mosaicism in the patients with AS clinical findings even if results of the methylation studies are normal.

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The evaluation of 15q proximal duplications by FISH

Cited by 16 publications

References 17 publications

Clinical and molecular characterization of a large family with an interstitial 15q11q13 duplication

Clinical and molecular characterization of a large family with an interstitial 15q11q13 duplication

Partial hexasomy for the Prader–Willi–Angelman syndrome critical region due to a maternally inherited large supernumerary marker chromosome

Fluorescence in situ hybridization detectable mosaicism for Angelman syndrome with biparental methylation

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