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Two cases of trisomy 16 mosaicism ascertained postnatally

Authors

  • Claudine Rieubland,

    Corresponding author
    1. Genetic Health Services Victoria, Royal Children's Hospital, Melbourne, Australia
    2. The Murdoch Childrens Research Institute, Melbourne, Australia
    • Genetic Health Services Victoria, Murdoch Childrens Research Institute, Royal Children's Hospital, Flemington Rd, Parkville 3052, Melbourne, Australia.
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  • David Francis,

    1. Genetic Health Services Victoria, Royal Children's Hospital, Melbourne, Australia
    2. The Murdoch Childrens Research Institute, Melbourne, Australia
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  • Leonie Houben,

    1. Genetic Health Services Victoria, Royal Children's Hospital, Melbourne, Australia
    2. The Murdoch Childrens Research Institute, Melbourne, Australia
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  • Sylvea Corrie,

    1. Genetic Health Services Victoria, Royal Children's Hospital, Melbourne, Australia
    2. The Murdoch Childrens Research Institute, Melbourne, Australia
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  • Agnes Bankier,

    1. Genetic Health Services Victoria, Royal Children's Hospital, Melbourne, Australia
    2. The Murdoch Childrens Research Institute, Melbourne, Australia
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  • Susan M. White

    1. Genetic Health Services Victoria, Royal Children's Hospital, Melbourne, Australia
    2. The Murdoch Childrens Research Institute, Melbourne, Australia
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  • How to cite this article: Rieubland C, Francis D, Houben L, Corrie S, Bankier A, White SM. 2009. Two cases of trisomy 16 mosaicism ascertained postnatally. Am J Med Genet Part A 149A:1523–1528.

Abstract

Postnatally ascertained trisomy 16 mosaicism is a rare diagnosis, with only three reported cases to date with no defined clinical phenotype. Trisomy 16 mosaicism diagnosed prenatally is common and associated with variable pregnancy outcomes ranging from stillbirth with multiple congenital abnormalities to an apparently normal newborn, making the genetic counseling very challenging. It is not clear whether uniparental disomy (UPD) 16 contributes to the phenotype, although it has been suggested that maternal UPD 16 affects the rate of intra-uterine growth retardation (IUGR) and congenital anomalies. We report on two further cases of trisomy 16 mosaicism confined to fibroblasts diagnosed postnatally. Patient 1 presented at birth with severe hypospadias, unilateral postaxial polydactyly, and different hair color with midline demarcation. His growth and development were normal at 11 months of age. Patient 2 was born with IUGR, significant craniofacial and body asymmetry, asymmetric skin hyperpigmentation, unilateral hearing loss, scoliosis, VSD, unexplained dilated cardiomyopathy, feeding difficulties, failure to thrive, and recurrent respiratory tract infections. She died at 7 months of age from respiratory failure. These two further cases of postnatally diagnosed trisomy 16 mosaicism highlight the variability of clinical features and outcome in this diagnosis. While Patient 2 presented with typical features of chromosomal mosaicism, Patient 1 had mild and transient features with essentially normal outcome, suggesting that trisomy 16 mosaicism may be under-diagnosed. © 2009 Wiley-Liss, Inc.

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