Improving the diagnostic approach to type I diabetes: the introduction of anti‐zinc transporter protein autoantibodies (ZnT8A) (835.15)

Abstract

Aim of the study. To evaluate the prevalence and persistence of ZnT8A, in a cohort of Pediatric diabetic patients, to assess reliability and relationship with other T1DM diagnostic markers. Methods. Sera from 97 T1DM pediatric patients (53.6% M/46.4% F, age 11.1 ± 3.9 yrs), and 112 controls (51.8% M/48.2% F, age 9.6 ± 4.9 yrs; with no T1D or family history of autoimmune diseases) were analyzed for IgG ZnT8, GADA, IA2A and AIA by ELISA, and for IgG Islet Cell Antibodies (ICA) by an indirect immunofluorescence test on cryostat primate’s pancreas.Results. ZnT8A (cut‐off 蠅 15 UA/ml) were present in 54.6% (53/97) T1DM patients (in two cases as the unique autoantibody) vs 97.3% (3/112) controls (p<0.0001). ZnT8A prevalence decreases among onset (25/40, 62.5%) and follow‐up patients with 5 or more years of disease (12/29, 41.3%). The prevalence of ICA at disease onset was 33.3% compared to 66.7% for GADA, 73.3% for IA2A, 73.3% for ZnT8A and 6% for AIA. Conclusions. The sensitivity (54.6%) and specificity (97.3%) of the ZnT8A in T1DM were in line with previous literature and comparable to those of the other major known diabetes autoantibodies. Even if ZnT8A do not persist as long as GADA after diagnosis, it represent a valid independent diagnostic marker for T1DM and its introduction in the Lab analysis is strongly recommended. In contrast, the sensibility of ICA appears unsatisfactory and its use as a screening test of limited value.