Johnson MB, et al. - Because patients with Down syndrome (DS) from trisomy 21 are four times more likely to have childhood diabetes with an intermediate HLA association, experts investigated whether DS could cause permanent neonatal diabetes mellitus (PNDM). Findings revealed that in 4 out of 9 DS-PNDM patients islet autoantibodies were seen; DS-PNDM was not related with polygenic susceptibility to type 1 diabetes. Investigators found that trisomy 21 was a cause of autoimmune PNDM that was not HLA associated. They suggested that autoimmune diabetes in DS was heterogeneous and includes HLA-associated coincidental type 1 diabetes and non-HLA-associated trisomy 21-related diabetes.