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Pallister–Killian syndrome caused by mosaicism for a supernumerary ring chromosome 12p

Authors

  • Alison Yeung,

    1. Victorian Clinical Genetics Services, Royal Children's Hospital, Melbourne, Australia
    2. Murdoch Childrens Research Institute, Royal Children's Hospital, Melbourne, Australia
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  • David Francis,

    1. Victorian Clinical Genetics Services, Royal Children's Hospital, Melbourne, Australia
    2. Murdoch Childrens Research Institute, Royal Children's Hospital, Melbourne, Australia
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  • Olivia Giouzeppos,

    1. Victorian Clinical Genetics Services, Royal Children's Hospital, Melbourne, Australia
    2. Murdoch Childrens Research Institute, Royal Children's Hospital, Melbourne, Australia
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  • David J. Amor

    Corresponding author
    1. Victorian Clinical Genetics Services, Royal Children's Hospital, Melbourne, Australia
    2. Murdoch Childrens Research Institute, Royal Children's Hospital, Melbourne, Australia
    3. Department of Paediatrics University of Melbourne, Melbourne, Australia
    • Victorian Clinical Genetic Services, Royal Children's Hospital, Flemington Road, Parkville, Victoria, Australia 3052.
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  • How to cite this article: Yeung A, Francis D, Giouzeppos O, Amor DJ. 2009. Pallister–Killian syndrome caused by mosaicism for a supernumerary ring chromosome 12p. Am J Med Genet Part A 149A:505–509.

Abstract

Pallister–Killian syndrome (PKS) is a rare but distinctive chromosomal syndrome distinguished by severe intellectual impairment, characteristic facial features, and variable structural anomalies. The characteristic cytogenetic abnormality in PKS is a supernumerary isochromosome 12p that confers mosaic tetrasomy. We describe a female child with PKS in whom tetrasomy 12p resulted from a supernumerary ring chromosome containing two copies of chromosome 12cen → p13, a novel cytogenetic finding. The ring chromosome exhibited tissue-limited mosaicism, being absent in blood but detected in 38% of buccal mucosa cells and 41% of skin fibroblasts. Our patient demonstrated the typical dysmorphic characteristics of PKS, but her development was relatively advanced in comparison to children with isochromosome PKS. Her milder developmental phenotype may be attributable to differences in the mosaic distribution or the genomic content of the ring chromosome compared to mosaic isochromosome 12p. © 2009 Wiley-Liss, Inc.

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