['The factors determining the pathogenesis of transient and permanent neonatal diabetes mellitus are poorly characterized. The purpose of this study was to examine the role of chromosome 6 in the pathogenesis of neonatal diabetes mellitus and to detect differences between these 2 phenotypes.', 'Microsatellite markers (D6S334, D6S286, D6S310, D6S308, D6S292, D6S311, and D6S403) and human leukocyte antigen DQ alleles were examined using polymerase chain reaction and DNA fragment electrophoresis in 3 patients with transient and 3 patients with permanent neonatal diabetes mellitus. Humoral markers of islet cell autoimmunity and clinical characteristics were analyzed in the 2 groups.', 'A patient with transient neonatal diabetes mellitus (TND) and macroglossia carrying paternal uniparental isodisomy (UPD) of chromosome 6 has been identified. The isodisomy affected the whole chromosome; no maternal chromosome 6 sequences were detected. The permanent neonatal diabetes mellitus cases and the other 2 cases with TND did not have UPD. None of the patients had high-risk type 1 diabetes human leukocyte antigen DQ alleles and most infants were negative for islet cell-specific autoantibodies indicating that none of the 2 forms of neonatal diabetes mellitus is likely to be of autoimmune origin. An association of TND and persistent granulocytopenia is described for the first time.'] Is transient but not permanent neonatal diabetes mellitus associated with paternal uniparental isodisomy of chromosome 6?