Prevalence and fate of type 1 diabetes-associated autoantibodies in cord blood samples from newborn infants of non-diabetic mothers.

Abstract

Cord blood samples were collected from 1002 consecutive births at Turku University Hospital to study the prevalence and fate of type 1 diabetes-associated autoantibodies in newborn infants of unaffected mothers. The samples were analysed for cytoplasmic islet cell antibodies (ICA), autoantibodies to the 65 kD isoform of glutamic acid decarboxylase (GADA), autoantibodies to the protein tyrosine phosphatase related IA-2 antigen (IA-2A), insulin autoantibodies (IAA) and HLA DQB1 genotypes. ICA were detected in 27 cord blood samples (2.7%), with a median of 6 (range 4-34) JDF units. GADA were found to be positive (> or =6.6 RU) in six samples (0.6%), with a median of 66 (range 19-125) RU. IA-2A (> or =0.43 RU) were observed in three samples (0.3%), with a median of 1.3 (range 0.8-57) RU, while only one cord blood sample (0.1%) tested positive for IAA (> or =1.56 nU/ml) with a value of 5.4 RU. Maternal or gestational age, sex and birth weight of the infant were not related to antibody prevalence or titres. Altogether there were 29 infants with antibody positivity in their cord blood (2.9%). Five of these (0.5%) tested positive for two antibodies (ICA and GADA), and one was positive for all four antibodies measured. All nine infants from whom follow-up samples were available became antibody negative by the age of 15 months, and in all but one case inverse seroconversion occurred by the age of 9 months. Around 3% of infants of non-diabetic mothers in Finland have diabetes-associated autoantibodies at birth, and these antibodies disappear at the latest by the age of 15 months.