Early-Onset, Coexisting Autoimmunity and Decreased HLA-Mediated Susceptibility Are the Characteristics of Diabetes in Down Syndrome

OBJECTIVE: Down syndrome (DS) is associated with an increased risk of diabetes, particularly in young children. HLA-mediated risk is however decreased in children with DS and diabetes (DSD). We hypothesized that early-onset diabetes in children with DS is etiologically different from autoimmune diabetes. RESEARCH DESIGN AND METHODS: Clinical and immunogenetic markers of autoimmune diabetes were studied in 136 individuals with DSD and compared with 194 age- and sex-matched individuals with type 1 diabetes, 222 with DS, and 671 healthy controls. HLA class II was analyzed by sequence-specific primed PCR. Islet autoantibodies were measured by radioimmunoassay. RESULTS: Age at onset of diabetes was biphasic, with 22% of DS children diagnosed before 2 years of age, compared with only 4% in this age-group with type 1 diabetes in the general population (P < 0.0001). The frequency of the highest-risk type 1 diabetes–associated HLA genotype, DR3-DQ2/DR4-DQ8, was decreased in both early- and later-onset DSD compared with age-matched children with type 1 diabetes (P < 0.0001), although HLA DR3-DQ2 genotypes were increased (P = 0.004). Antibodies to GAD were observed in all five samples tested from children diagnosed at ≤2 years of age, and persistent islet autoantibodies were detected in 72% of DSD cases. Thyroid and celiac disease were diagnosed in 74 and 14%, respectively, of the DSD cohort. CONCLUSIONS: Early-onset diabetes in children with DS is unlikely to be etiologically different from autoimmune diabetes occurring in older DS children. Overall, these studies demonstrate more extreme autoimmunity in DSD typified by early-onset diabetes with multiple autoimmunity, persistent islet autoantibodies, and decreased HLA-mediated susceptibility

Analysis of transcription factors key for mouse pancreatic development establishes NKX2-2 and MNX1 mutations as causes of neonatal diabetes in man

notes: PMCID: PMC3887257This is a freely-available open access publication. Please cite the published version which is available via the DOI link in this record.Understanding transcriptional regulation of pancreatic development is required to advance current efforts in developing beta cell replacement therapies for patients with diabetes. Current knowledge of key transcriptional regulators has predominantly come from mouse studies, with rare, naturally occurring mutations establishing their relevance in man. This study used a combination of homozygosity analysis and Sanger sequencing in 37 consanguineous patients with permanent neonatal diabetes to search for homozygous mutations in 29 transcription factor genes important for murine pancreatic development. We identified homozygous mutations in 7 different genes in 11 unrelated patients and show that NKX2-2 and MNX1 are etiological genes for neonatal diabetes, thus confirming their key role in development of the human pancreas. The similar phenotype of the patients with recessive mutations and mice with inactivation of a transcription factor gene support there being common steps critical for pancreatic development and validate the use of rodent models for beta cell development.Wellcome TrustDiabetes UKEuropean Community’s Seventh Framework Programme (FP7/2007-2013