Quantitation of gene expression by real-time PCR disproves a "retroviral hypothesis" for childhood-onset diabetes mellitus

Children with insulin-dependent diabetes mellitus (IDDM) suffer from a chro nic autoimmune beta cell destruction of unknown origin, maybe due to supera ntigens or retroviral endogenous genes. Recently, a novel endogenous retrov irus designated as IDDMK(1,2)22 was proposed to encode for such a candidate autoimmune gene in type 1 diabetes. We therefore analyzed the expression o f IDDMK(1,2)22 genes in peripheral blood leukocytes and plasma from 55 heal thy children and 55 diabetic children including 11 patients with acute dise ase onset. In our study we applied an improved quantitative and highly spec ific real-time PCR assay, In contrast to previous data obtained by conventi onal PCR, IDDMK(1,2)22 gene expression did not differ between diabetic and nondiabetic individuals. For this reason, we propose that IDDMK(1,2)22 is a n ubiquitous endogenous retroviral element in the human genome but not a ca ndidate autoimmune gene for IDDM, especially in childhood-onset disease. Re al-time PCR proved to be a highly sensitive and specific method for detecti on and quantitation of very low amounts of mRNA and will thereby be useful regarding the special demands in pediatric studies dealing with very low am ounts of specimen.