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Transient neonatal diabetes mellitus type 1


  • Deborah J.G. Mackay,

    Corresponding author
    • Wessex Regional Genetics Laboratory, Salisbury District Hospital, Salisbury SP2 8BJ, UK.
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    • Deborah Mackay, Ph.D. is a senior lecturer in human genetics at the University of Southampton, UK, and heads the Wessex Imprinting Group, which is embedded in a service genetics laboratory and delivers wide-ranging translational research into human imprinting disorders.

  • I. Karen Temple

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    • Karen Temple, M.D., FRCP, MBChB is Professor of Medical Genetics and Divisional Director of Human Genetics at the University of Southampton, UK. Over two decades her clinical research has made a critical impact on the understanding of imprinting syndromes including the transient neonatal diabetes, Beckwith–Wiedemann, Russell–Silver and Temple syndromes.

  • How to cite this article: Mackay DJG, Temple IK. 2010. Transient neonatal diabetes mellitus type 1. Am J Med Genet Part C Semin Med Genet 153C:335–342.


Transient neonatal diabetes mellitus type 1 (TNDM1) is a rare but remarkable form of diabetes which presents in infancy, resolves in the first months of life, but then frequently recurs in later life. It is caused by overexpression of the imprinted genes PLAGL1 and HYMAI on human chromosome 6q24. The expression of these genes is normally restricted to the paternal allele as a result of maternal DNA methylation. TNDM1 is not associated with mutation of PLAGL1 or HYMAI, but rather with their overexpression via uniparental disomy, chromosome duplication, or relaxation of imprinting. Study of patients with TNDM1 has provided valuable insights into the causes of imprinting disorders. Over half of patients with maternal hypomethylation at the TNDM1 locus have additional hypomethylation of other maternally methylated imprinted genes throughout the genome, and the majority of these patients have mutations in the transcription factor ZFP57. TNDM1 with maternal hypomethylation has also been observed in patients conceived by assisted reproduction, and in discordant monozygotic twins. The variable clinical features of TNDM1 may be associated with variation in the nature of the underlying epigenetic and genetic mutations, and future study of this disorder is likely to yield further insights not only into the biological mechanisms of imprinting, but also into the contribution of epigenetics to diabetes. © 2010 Wiley-Liss, Inc.