Age-Specific Levels of Diabetes-Related GAD and IA-2 Antibodies in Healthy Children and Adults

Abstract

Glutamic acid decarboxylase (GAD) and tyrosine phosphatase IA-2 antibody levels were measured in 375 healthy children and adults and in 187 children with newly diagnosed type 1 diabetes mellitus (DM). GAD antibody levels were determined by radioimmunoassay, and IA-2 antibody levels by immunoprecipitation. Healthy children had higher GAD antibody levels than adults (p < 0.001). The 98th percentile was 1.60 U/ml in children and 1.16 U/ml in adults. IA-2 antibody levels did not differ between these two cohorts. Children with DM had higher GAD and IA-2 antibody levels than healthy children (p <0.001). Based on receiver operating characteristics (ROC) analysis, elevated levels of these antibodies showed high specificity rates (+/- SE) of 0.968 +/- 0.14 to 1.00 +/- 0.00. The sensitivity ranged between 0.439 +/- 0.037 (both antibodies elevated) and 0.850 +/- 0.027 (at least one antibody elevated). These data emphasize the importance of establishing age-specific reference values for DM-related antibodies in the background population before applying them for screening and intervention studies.

Autoantibodies targeting neurotransmitter biosynthetic enzymes in attention-deficit/hyperactivity disorder (ADHD)

“…This frequency is in line with previous studies of GAD65 antibodies in the presumed healthy population [13]. Therefore, we find it unlikely that GAD65 antibodies are frequently observed or involved in the pathophysiology of ADHD.…”

“…It is thought that the levels of GAD65 antibodies in the healthy population reach a top during childhood and subsequently falls as the individual ages [13]. In addition there are known sex differences in the prevalence of several of the autoimmune disorders [15].…”

Comparison of the prevalence of islet autoantibodies according to age and disease duration in patients with type 1 diabetes mellitus

“…In the comparison between the prepuberty and the postpuberty groups, the prevalence of anti-GAD Ab-, ICA512-, and IAA-positive patients was higher in the prepuberty groups than in the postpuberty groups. Previous studies21,22) reported that younger subjects showed higher levels of islet autoantibodies to T1DM. However, the cause was not clearly identified21,22).…”

“…Previous studies21,22) reported that younger subjects showed higher levels of islet autoantibodies to T1DM. However, the cause was not clearly identified21,22). The research by Kordonouri et al21) showed that concentrations of anti-GAD Ab and IA-2 Ab were higher in a pubertal group than in an adult group, both of which were healthy and not diagnosed with DM.…”

“…However, the cause was not clearly identified21,22). The research by Kordonouri et al21) showed that concentrations of anti-GAD Ab and IA-2 Ab were higher in a pubertal group than in an adult group, both of which were healthy and not diagnosed with DM. This difference in the positive rate of islet autoantibodies among the age groups is also seen in diseases other than T1DM, with one study reporting apparent differences in the concentration of total immunoglobulin among different age groups, suggesting that antibody concentrations can vary among different age groups23).…”