Article

Unique and atypical deletions in Prader-Willi syndrome reveal distinct phenotypes

Department of Psychiatry, University of Florida, Gainesville, FL, USA.
European journal of human genetics: EJHG (Impact Factor: 4.23). 11/2011; 20(3):283-90. DOI: 10.1038/ejhg.2011.187
Source: PubMed

ABSTRACT Prader-Willi syndrome (PWS) is a multisystem, contiguous gene disorder caused by an absence of paternally expressed genes within the 15q11.2-q13 region via one of the three main genetic mechanisms: deletion of the paternally inherited 15q11.2-q13 region, maternal uniparental disomy and imprinting defect. The deletion class is typically subdivided into Type 1 and Type 2 based on their proximal breakpoints (BP1-BP3 and BP2-BP3, respectively). Despite PWS being a well-characterized genetic disorder the role of the specific genes contributing to various aspects of the phenotype are not well understood. Methylation-specific multiplex ligation-dependent probe amplification (MS-MLPA) is a recently developed technique that detects copy number changes and aberrant DNA methylation. In this study, we initially applied MS-MLPA to elucidate the deletion subtypes of 88 subjects. In our cohort, 32 had a Type 1 and 49 had a Type 2 deletion. The remaining seven subjects had unique or atypical deletions that were either smaller (n=5) or larger (n=2) than typically described and were further characterized by array-based comparative genome hybridization. In two subjects both the PWS region (15q11.2) and the newly described 15q13.3 microdeletion syndrome region were deleted. The subjects with a unique or an atypical deletion revealed distinct phenotypic features. In conclusion, unique or atypical deletions were found in ∼8% of the deletion subjects with PWS in our cohort. These novel deletions provide further insight into the potential role of several of the genes within the 15q11.2 and the 15q13.3 regions.

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    Chapter: Epigenetics
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    ABSTRACT: This article was originally published in Pathobiology of Human Disease, a Dynamic Encyclopedia of Disease Mechanisms, published by Elsevier, and the attached copy is provided by Elsevier for the author's benefit and for the benefit of the author's institution, for non-commercial research and educational use including without limitation use in instruction at your institution, sending it to specific colleagues who you know, and providing a copy to your institution's administrator. All other uses, reproduction and distribution, including without limitation commercial reprints, selling or licensing copies or access, or posting on open internet sites, your personal or institution's website or repository, are prohibited. For exceptions, permission may be sought for such use through Elsevier's permissions site at: http://www.elsevier.com/locate/permissionusematerial Tirado C.A. (2014) Epigenetics. In: Linda M. McManus, Richard N. Mitchell, editors. Pathobiology of Human Disease. San Diego: Elsevier; p. 3399-3407.
    Pathobiology of HUMAN DISEASE, Edited by Linda M. McManus, Richard N. Mitchell, editors, 11/2014: chapter Epigenetics: pages 3399-3407; Elsevier.
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    ABSTRACT: The SNORD116 locus lies in the 15q11-13 region of paternally expressed genes implicated in Prader-Willi Syndrome (PWS), a complex disease accompanied by obesity and severe neurobehavioural disturbances. Cases of PWS patients with a deletion encompassing the SNORD116 gene cluster, but preserving the expression of flanking genes, have been described. We report a 23-year-old woman who presented clinical criteria of PWS, including the behavioural and nutritional features, obesity, developmental delay and endocrine dysfunctions with hyperghrelinemia. We found a paternally transmitted highly restricted deletion of the SNORD116 gene cluster, the shortest described to date (118 kb). This deletion was also present in the father. This finding in a human case strongly supports the current hypothesis that lack of the paternal SNORD116 gene cluster has a determinant role in the pathogenesis of PWS. Moreover, targeted analysis of the SNORD116 gene cluster, complementary to SNRPN methylation analysis, should be carried out in subjects with a phenotype suggestive of PWS.European Journal of Human Genetics advance online publication, 11 June 2014; doi:10.1038/ejhg.2014.103.
    European journal of human genetics: EJHG 06/2014; 23(2). DOI:10.1038/ejhg.2014.103 · 4.23 Impact Factor
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    ABSTRACT: The objectives of the present study were to investigate eating behavior and growth parameters in Angelman syndrome. We included 39 patients with Angelman syndrome. Twelve cases had a larger Class I deletion, eighteen had a smaller Class II deletion, whereas paternal uniparental disomy (pUPD) or a verified UBE3A mutation were present in five and four cases, respectively. Eating behavior was assessed by a questionnaire. Anthropometric measures were obtained from medical records and compared to Danish reference data. Children with pUPD had significantly larger birth weight and birth length than children carrying a deletion or a UBE3A mutation. We found no difference in birth weight or length in children with Class I or Class II deletions. When maternal birth weight and/or birth weight of siblings were taken into consideration, children with Class I deletion had a lower weight at birth than expected, and the weight continued to be reduced during the investigated initial five years of life. In contrast, children with pUPD showed hyperphagic behavior and their weight increased significantly after the age of two years. Accordingly, their body mass index was significantly increased as compared to children with a deletion. At birth, one child showed microcephaly. At five years of age, microcephaly was observed in half of the deletion cases, but in none of the cases with a UBE3A mutation or pUPD. The apparently normal cranial growth in the UBE3A and pUPD patients should however be regarded as the result of a generally increased growth. Eating behavior, pre- and postnatal growth in children with Angelman syndrome depends on genotype.
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