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Trisomy 17p10-p12 due to mosaic supernumerary marker chromosome: Delineation of molecular breakpoints and clinical phenotype, and comparison to other proximal 17p segmental duplications

Authors

  • Svetlana A. Yatsenko,

    1. Department of Molecular & Human Genetics, Baylor College of Medicine, Houston, Texas
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  • Diane Treadwell-Deering,

    1. Department of Pediatrics, Baylor College of Medicine, Houston, Texas
    2. Department of Psychiatry and Behavioral Sciences, Baylor College of Medicine, Houston, Texas
    3. Texas Children's Hospital, Houston, Texas
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  • Kevin Krull,

    1. Department of Pediatrics, Baylor College of Medicine, Houston, Texas
    2. Department of Psychiatry and Behavioral Sciences, Baylor College of Medicine, Houston, Texas
    3. Texas Children's Hospital, Houston, Texas
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  • Richard Alan Lewis,

    1. Department of Molecular & Human Genetics, Baylor College of Medicine, Houston, Texas
    2. Department of Pediatrics, Baylor College of Medicine, Houston, Texas
    3. Department of Ophthalmology, Baylor College of Medicine, Houston, Texas
    4. Department of Medicine, Baylor College of Medicine, Houston, Texas
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  • Daniel Glaze,

    1. Department of Pediatrics, Baylor College of Medicine, Houston, Texas
    2. Department of Neurology, Baylor College of Medicine, Houston, Texas
    3. Texas Children's Hospital, Houston, Texas
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  • Pawel Stankiewicz,

    1. Department of Molecular & Human Genetics, Baylor College of Medicine, Houston, Texas
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  • James R. Lupski,

    1. Department of Molecular & Human Genetics, Baylor College of Medicine, Houston, Texas
    2. Department of Pediatrics, Baylor College of Medicine, Houston, Texas
    3. Texas Children's Hospital, Houston, Texas
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  • Lorraine Potocki

    Corresponding author
    1. Department of Molecular & Human Genetics, Baylor College of Medicine, Houston, Texas
    2. Texas Children's Hospital, Houston, Texas
    • Department of Molecular & Human Genetics, Baylor College of Medicine, Texas Children's Hospital, Clinical Care Center, Mail Code CCC-1560, Houston, TX 77030.
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Abstract

The unstable, gene-rich chromosome region 17p11.2-p12 is associated with various structural aberrations including supernumerary marker chromosomes (SMCs). In some cases, SMC(17)s utilize the same substrates for recombination as the common recurrent 17p11.2 and 17p12 rearrangements. We report on a 9-year-old girl with a de novo mosaic SMC(17). The der(17) encompasses genetic material from 17p10-p11.2 and is present in 97% of peripheral blood lymphocytes and in 79% of buccal cells. The patient has few features similar to individuals with duplication 17p11.2 including mental retardation, language impairment, and sleep disturbances but has normal growth, and no structural abnormalities of the heart, kidneys, or brain. She has no substantial behavioral abnormalities or dysmorphic features. Molecular analyses determined that the der(17) contains RAI1 but not PMP22. We found one chromosome breakpoint within the centromere and the second breakpoint within the distal Smith–Magenis syndrome low-copy repeat (distal SMS-REP). Recently we characterized the breakpoints of three other marker chromosomes originating from the proximal short arm of chromosome 17. In all four cases, one breakpoint maps within the centromere and in three cases the second breakpoint maps within a low-copy repeat. We thus propose that genome architecture may play a significant role in the formation of marker chromosomes. We present the cytogenetic, molecular, and clinical data of this patient and compare our results with those of patients with dup(17)(p11.2p11.2) syndrome and other patients with SMC(17). © 2005 Wiley-Liss, Inc.

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