Identification of monogenic gene mutations in Japanese subjects diagnosed with type 1B diabetes between >5 and 15.1 years of age.

BACKGROUND: Monogenic mutations, such as those in the potassium inwardly-rectifying channel, subfamily J, member 11 (KCNJ11) and insulin (INS) genes, are identified in young patients with type 1B diabetes (non-autoimmune-mediated). We recently reported the results of a test for monogenic forms of diabetes in Japanese children who were diagnosed with type 1B diabetes at <5 years of age. In this study, we tested for monogenic forms of diabetes in Japanese children aged >5 to ≤15.1 years at the diagnosis of type 1B diabetes. METHODS: Thirty-two Japanese children (eight males, 24 females) with type 1 diabetes negative for glutamate decarboxylase (GAD) 65 and/or IA-2A autoantibodies and who were aged >5 to 15.1 years at diagnosis were recruited from 16 independent hospitals participating in the Japanese Study Group of Insulin Therapy for Childhood and Adolescent Diabetes (JSGIT). We performed mutational analyses of genes with a high frequency of mutation [INS, KCNJ11, hepatocyte nuclear factor 1 alpha (HNF1α) and hepatocyte nuclear factor 4 alpha (HNF4α)]. RESULTS: We identified one missense mutation (G32S) in the INS gene and two mutations (R131Q and R203S) in the HNF1α gene that could be associated with diabetes. No missense change was found in the KCNJ11 gene. CONCLUSIONS: Our results suggest that although mutations in the INS gene can be detected in Japanese patients aged >5 years at diagnosis, the frequency of mutations decrease in older age groups. Conversely, the frequency of the mutation in the HNF1α gene increased in patients diagnosed at age 5 or older. Clinicians should consider the possibility of maturity onset diabetes of the young (MODY) in children diagnosed with type 1B diabetes.

Usefulness of insulin detemir in Japanese children with type 1 diabetes.

BACKGROUND: This multicenter observational study was conducted to investigate the efficacy and safety of insulin detemir (detemir) for diabetes management in Japanese children and adolescents. METHODS: Data from the Japanese Study Group of Insulin Therapy for Childhood and Adolescent Diabetes database were analyzed. Ninety children (32 boys, 58 girls; mean age, 11.9 ± 3.8 years) who transferred from a neutral protamine Hagedorn insulin or insulin glargine basal-bolus regimen to detemir basal-bolus therapy and who were observed for at least 12 months were identified. Clinical data obtained at 0, 3, 6, and 12 months were analyzed to determine the type of bolus insulin used, number and timing of detemir injections, detemir dose as a proportion of the total insulin dose, hemoglobin A1c (HbA1c), fasting blood glucose (FBG) and frequency of severe hypoglycemia. RESULTS: Twelve months after switching to detemir, the detemir dose represented 39.8% of the total insulin dose, and 37.8% of patients were being treated with twice-daily injections. HbA1c and FBG were significantly reduced from baseline at 3 and 6 months but not at 12 months. Considering the seasonal HbA1c variation in the Japanese population, a separate analysis was performed using data for 65 children (21 boys, 44 girls; mean age, 11.6 ± 2.9 years) who switched to detemir during the winter. Subset analysis showed significant HbA1c reductions from baseline at all specified times. The incidence of severe hypoglycemia during detemir treatment was 4.4 episodes per 100 patient-years. CONCLUSIONS: Detemir is an effective and safe basal insulin for diabetes management in Japanese children and adolescents.

HLA-class II and class I genotypes among Japanese children with Type 1A diabetes and their families.

OBJECTIVE: To determine the HLA-DRB1, DQB1, DPB1, A, C, and B genotypes among Japanese children with autoimmune type 1 diabetes. METHODS: Four hundred and thirty patients who were GADAb and/or IA-2Ab-positive (Type 1A) were recruited from 37 medical centers as part of a nationwide multicenter collaborative study. DNA samples from 83 siblings of the children with Type 1A diabetes and 149 parent-child trios were also analyzed. A case-control study and a transmission disequilibrium test (TDT) were then performed. RESULTS: The susceptible and protective DRB1 and DQB1 alleles and haplotypes were confirmed. DPB1 alleles unique to the Japanese population and those common to multiple ethnic groups were also present. A linkage disequilibrium (LD) analysis showed both susceptible and protective haplotypes. The TDT did not reveal any alleles that were transmitted preferentially from the mother or father to children with Type 1A. Homozygosity for DRB1-09:01-DQB1-03:03 and heterozygosity for DRB1-04:05-DQB1-04:01 and DRB1-08:02-DQB1-03:02 were associated with an extremely high risk of Type 1A. A comparison of children with Type 1A and their parents and siblings suggested a dose effect of susceptible DRB1-DQB1 haplotypes and an effect of protective alleles on immunological pathogenesis. DRB1-09:01 appeared to be strongly associated with an early onset in preschool children with Type 1A diabetes. CONCLUSIONS: This study demonstrated the characteristic association of HLA-class II and class I genes with Type 1A diabetes among Japanese children. A TDT did not reveal the genomic imprinting of HLA-class II and class I genes in Type 1A diabetes.