Prevalence and Diagnostic Value of Zinc Transporter 8 (ZnT8) Antibodies in Bulgarian Population with Type 1 Diabetes
Author: Grozeva, Greta G., Chakarova, Nevena Y., Dimova, Rumyana B., Tankova, Tsvetalina Iv., Atanassova, Iliana B.
Department of Diabetology, Clinical Center of Endocrinology, Medical University, Sofia
A new immunologic marker – antibody to zinc transporter 8 (ZnT8-Ab), has been established in the diagnosis of type 1 diabetes in recent years. The aim of the study is to investigate the prevalence and diagnostic value of ZnT8-Ab in a Bulgarian population of type 1 diabetes patients. Material and methods: 70 patients (40 males and 30 females), of mean age 37,24 ±11,08 years and mean BMI 23,46±4,49 kg/m2 , of up to 5 years duration of the disease (in 47% of the patients diabetes being newlydiagnosed or of less than a year duration), were investigated. Antibodies to beta-cell structures, antibodies to glutamic acid decarboxylase, GAD 65-Ab, antibodies to thyrosin phosphatase and IA 2-Ab and ZnT8-Ab were assessed. Results: Оne or more of the investigated antibodies were detected in 85,7% of the participants, ZnT8-Ab being the second most prevalent – in 45,7% of the group, following GAD 65-Ab – 77,1% and exceeding the prevalence of IA-2-Ab – 34,3%. 14,3% of the participants were triple negative. 2,9% of the participants were positive to ZnT8 which accounts for 16,6% of the cases of idiopathic type 1 diabetes. ZnT8-Ab was significantly more prevalent in the subgroup with newly-diagnosed diabetes and diabetes of less than a year’s duration – 63,6%, (p=0,04). The assessment of the classical combination GAD 65-Ab + IA-2-Ab identified 83% of type 1 diabetes cases (F=[2,3] 43,4, р<0.001, r=0,462). The use of ZnT8-Ab instead of IA 2-Ab as a second immunologic marker identified more cases of type 1 diabetes – 87% (F=[2,3] 46,6, р < 0,001, r=0,486), and the combination of all the three antibodies led to the diagnosis of 92% of the type 1 diabetes cases (F=[3,3] 50,7, р = 0,043, r=0,515). Conclusions: In adult patients with autoimmune diabetes ZnT8-Ab is the second most prevalent antibody and the second in diagnostic importance after GAD 65-Ab. The assessment of ZnT8-Ab in addition to GAD 65- Ab and IA 2-Ab reduces the cases of idiopathic type 1 diabetes and the use of ZnT8-Ab as a second immunologic marker in addition to GAD 65-Ab outweighs the established combination of GAD 65-Ab+IA 2-Ab.
Key words: zinc transporter 8, type 1 diabetes, antibodies, beta-cell