Measurement of differentially methylated INS DNA species in human serum samples as a biomarker of islet β cell death

Sarah A. Tersey, Jennifer B. Nelson, Marisa M. Fisher, Raghavendra G. Mirmira

Research output: Contribution to journalArticlepeer-review

6 Scopus citations


The death of islet β cells is thought to underlie the pathogenesis of virtually all forms of diabetes and to precede the development of frank hyperglycemia, especially in type 1 diabetes. The development of sensitive and reliable biomarkers of β cell death may allow for early therapeutic intervention to prevent or delay the development of diabetes. Recently, several groups including our own have reported that cell-free, differentially methylated DNA encoding preproinsulin (INS) in the circulation is correlated to β cell death in pre-type 1 diabetes and new-onset type 1 diabetes. Here, we present a step-by-step protocol using digital PCR for the measurement of cell-free INS DNA that is differentially methylated at cytosine at position -69 bp (relative to the transcriptional start site). We demonstrate that the assay can distinguish between methylated and unmethylated cytosine at position -69 bp, is linear across several orders of magnitude, provides absolute quantitation of DNA copy numbers, and can be applied to samples of human serum from individuals with new-onset type 1 diabetes and disease-free controls. The protocol described here can be adapted to any DNA species for which detection of differentially methylated cytosines is desired, whether from circulation or from isolated cells and tissues, and can provide absolute quantitation of DNA fragments.

Original languageEnglish (US)
Article numbere54838
JournalJournal of Visualized Experiments
Issue number118
StatePublished - Dec 21 2016


  • Biomarker
  • Diabetes
  • Digital PCR
  • Epigenetics
  • Genetics
  • Insulin
  • Islet
  • Issue 118

ASJC Scopus subject areas

  • Neuroscience(all)
  • Chemical Engineering(all)
  • Biochemistry, Genetics and Molecular Biology(all)
  • Immunology and Microbiology(all)

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