Prevalence of Autoimmune Antibodies in Type I Diabetic Children and Their Siblings / 대한소아내분비학회지

ABSTRACT

Background:Insulin dependent diabetes mellitus(IDDM) is known to be a disease characterized by a deficiency of insulin caused by destruction of the pancreatic beta-cells. It has been suggested that the clinical and immunological characteristics of IDDM in Korean are different from those of Caucasian. This study was undertaken to investigate the clinical characteristics and the prevalence of autoimmune markers in type I diabetic children and their prediabetic siblings in Korea. METHODS:Insulin autoantibody(IAA), antiglutamic acid decarboxylase(Anti-GAD) antibody, thyroid autoantibodies such as antithyroid antibody(ATA) and antimicrosomal antibody(AMA), and rheumatoid facter(RF) in 54 type I diabetic children have been measured. Diabetic autoimmune antibodies were also measured in 48 siblings. RESULTS: 1)Clinical characteristics of type I diabetic children were that age of onset was 8.6+/-4.4 years, duration of diabetes was 4.1+/-3.3 years. C-peptide at onset of diabetes was fasting 0.7+/-0.5ng/ml, and postprandial 1.2+/-0.5ng/ml, and HbA1c was 12.5+/-4.3%. 2)The positivity of IAA and anti-GAD antibody of type I diabetic children was 74% and 50% respectively. ATA and AMA positivity of type I diabetic children was 3.7% and 5.6%. however RF was not detected at all. Among the diabetic siblings, 48 persons for anti-GAD antibody, 21 for IAA, 27 for ICA were measured but 1 case was positive for IAA. 3)Clinical characteristics of type I diabetic children were not specific different between IAA and anti-GAD antibody positivity. But the mean age of onset of type I diabetic children was younger in case of both positivity of IAA and anti-GAD antibody than both negativity(7.8 vs 11.4 years old, P<0.05). 4)A case in whose brothers are diagnosed as IDDM has shown that autoantibody of elder brother was positive in both IAA and anti-GAD antibody, and younger brother was also strongly positive in IAA. Another case in whose sisters were IDDM, has shown that, while elder sister was positive in IAA, younger sister strongly positive in both IAA and anti-GAD antibody. 5)In a case of identical twin brother, the elder is type I diabetic child and the younger is normal, elder brother's onset of age was 6 years and 8 months old, and titer of anti-GAD antibody was measured as strong positive. Both ICA and anti- GAD antibody were negative in normal younger brother. First phase insulin release in IV GTT and the insulin levels in oral GTT showed reduction from the normal level in normal brother, and repeat check up showed normal ranges but on-going study is needed under observation. CONCLUSION: The prevalence of autoantibody positivity of type I diabetic children of Korea in this study were IAA 74%, and anti-GAD antibody 50%. Cases with both IAA and anti-GAD antibody positive were shown to be earlier onset. Though titers of auto-antibody in IDDM twins, brothers and sisters were strongly positive, auto-antibodies in siblings of IDDM patients were detected only one case with IAA positive(0.47%). We suggest that the pathogenesis of IDDM in Korean is different from foreign countries in terms of prevalence of autoimmune antibodies and more numbers of diabetic siblings should be tested for further study.