title: Elevations in Circulating Methylated and Unmethylated Preproinsulin DNA in New-Onset Type 1 Diabetes.
abstract: Elevated ratios of circulating unmethylated to methylated preproinsulin (INS) DNA have been suggested to reflect β-cell death in type 1 diabetes (T1D). We tested the hypothesis that absolute levels (rather than ratios) of unmethylated and methylated INS DNA differ between subjects with new-onset T1D and control subjects and assessed longitudinal changes in these parameters. We used droplet digital PCR to measure levels of unmethylated and methylated INS DNA in serum from subjects at T1D onset and at 8 weeks and 1 year post-onset. Compared with control subjects, levels of both unmethylated and methylated INS DNA were elevated at T1D onset. At 8 weeks post-onset, methylated INS DNA remained elevated, but unmethylated INS DNA fell. At 1 year postonset, both unmethylated and methylated INS DNA returned to control levels. Subjects with obesity, type 2 diabetes, and autoimmune hepatitis exhibited lower levels of unmethylated and methylated INS compared with subjects with T1D at onset and no differences compared with control subjects. Our study shows that elevations in both unmethylated and methylated INS DNA occurs in new-onset T1D and that levels of these DNA species change during T1D evolution. Our work emphasizes the need to consider absolute levels of differentially methylated DNA species as potential biomarkers of disease.
authors.affiliation: Department of Pediatrics, Indiana University School of Medicine, Indianapolis, IN Center for Diabetes and Metabolic Diseases, Indiana University School of Medicine, Indianapolis, IN.
authors.forename: Marisa M
authors.initials: MM
authors.lastname: Fisher
authors.affiliation: Department of Pediatrics, Indiana University School of Medicine, Indianapolis, IN Center for Diabetes and Metabolic Diseases, Indiana University School of Medicine, Indianapolis, IN.
authors.forename: Renecia A
authors.initials: RA
authors.lastname: Watkins
authors.affiliation: Center for Diabetes and Metabolic Diseases, Indiana University School of Medicine, Indianapolis, IN Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, IN.
authors.forename: Janice
authors.initials: J
authors.lastname: Blum
authors.affiliation: Center for Diabetes and Metabolic Diseases, Indiana University School of Medicine, Indianapolis, IN Department of Medicine, Indiana University School of Medicine, Indianapolis, IN Department of Cellular and Integrative Physiology, Indiana University School of Medicine, Indianapolis, IN Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN.
authors.forename: Carmella
authors.initials: C
authors.lastname: Evans-Molina
authors.affiliation: Center for Diabetes and Metabolic Diseases, Indiana University School of Medicine, Indianapolis, IN Department of Medicine, Indiana University School of Medicine, Indianapolis, IN Department of Cellular and Integrative Physiology, Indiana University School of Medicine, Indianapolis, IN.
authors.forename: Naga
authors.initials: N
authors.lastname: Chalasani
authors.affiliation: Department of Pediatrics, Indiana University School of Medicine, Indianapolis, IN Center for Diabetes and Metabolic Diseases, Indiana University School of Medicine, Indianapolis, IN.
authors.forename: Linda A
authors.initials: LA
authors.lastname: DiMeglio
authors.affiliation: Center for Diabetes and Metabolic Diseases, Indiana University School of Medicine, Indianapolis, IN Department of Medicine, Indiana University School of Medicine, Indianapolis, IN.
authors.forename: Kieren J
authors.initials: KJ
authors.lastname: Mather
authors.affiliation: Department of Pediatrics, Indiana University School of Medicine, Indianapolis, IN Center for Diabetes and Metabolic Diseases, Indiana University School of Medicine, Indianapolis, IN.
authors.forename: Sarah A
authors.initials: SA
authors.lastname: Tersey
authors.affiliation: Department of Pediatrics, Indiana University School of Medicine, Indianapolis, IN Center for Diabetes and Metabolic Diseases, Indiana University School of Medicine, Indianapolis, IN Department of Medicine, Indiana University School of Medicine, Indianapolis, IN Department of Cellular and Integrative Physiology, Indiana University School of Medicine, Indianapolis, IN Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN rmirmira@iu.edu.
authors.forename: Raghavendra G
authors.initials: RG
authors.lastname: Mirmira
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D004247:DNA / Q000097:blood*; D019175:DNA Methylation; D003922:Diabetes Mellitus, Type 1 / Q000097:blood*; D005260:Female; D006801:Humans; D007328:Insulin / Q000097:blood* / Q000235:genetics; D008297:Male; D011498:Protein Precursors / Q000097:blood* / Q000235:genetics
chemical_list: D007328:Insulin; D011498:Protein Precursors; C013737:preproinsulin; D004247:DNA