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Mosaic paternal uniparental (iso)disomy for chromosome 20 associated with multiple anomalies

Authors

  • Charles P. Venditti,

    1. Division of Human Genetics and Molecular Biology, Department of Pediatrics, The Children's Hospital of Philadelphia, Pennsylvania
    2. Department of Genetics, The University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania
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  • Piper Hunt,

    1. Department of Biological Chemistry, The Johns Hopkins University School of Medicine, Baltimore, Maryland
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  • Alan Donnenfeld,

    1. Genzyme Genetics, 800 Chestnut Street, Philadelphia, Pennsylvania
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  • Elaine Zackai,

    1. Division of Human Genetics and Molecular Biology, Department of Pediatrics, The Children's Hospital of Philadelphia, Pennsylvania
    2. Department of Genetics, The University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania
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  • Nancy B. Spinner

    Corresponding author
    1. Division of Human Genetics and Molecular Biology, Department of Pediatrics, The Children's Hospital of Philadelphia, Pennsylvania
    2. Department of Genetics, The University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania
    3. Division of Clinical Laboratories, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania
    • Division of Human Genetics and Molecular Biology, 1007A Abramson Research Center, 3615 Civic Center Blvd, Philadelphia, PA 19104.
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Abstract

Uniparental disomy for a number of human chromosomes is associated with clinical abnormalities. We report a child with a complex chromosomal rearrangement involving chromosome 20 (45,XY,psu dic (20;20)(p13;p13)) and paternal uniparental isodisomy for chromosome 20 in peripheral blood and bone marrow. This patient had multiple congenital abnormalities including microtia/anotia, micrencephaly, congenital heart disease, neuronal subependymal heterotopias, and colonic agangliosis. Molecular studies on DNA from peripheral blood demonstrated paternal uniparental inheritance of chromosome 20. However, fibroblasts demonstrated a mosaic karyotype, with one cell line having 45 chromosomes, including the pseudodicentric chromosome 20 (75% of cells), and a second cell line having 46 chromosomes, including the pseudodicentric chromosome 20, and a normal chromosome 20 (trisomy 20) (25% of cells). FISH experiments using a sub-telomeric probe that maps ∼120 kb from the 20p telomere, showed that both copies of these sequences were present on the rearranged chromosome, consistent with deletion of a very small interval. This leads us to suggest that in addition to trisomy 20 mosaicism, paternal uniparental disomy for chromosome 20 could contribute to his clinical phenotype. © 2003 Wiley-Liss, Inc.

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