Ketoacidosis at diagnosis in childhood-onset diabetes and the risk of retinopathy 20years later.

AIMS: To investigate on the relationship between severity of ketoacidosis, an important risk factor for C-peptide preservation, and long-term microvascular complications in childhood-onset type 1 diabetes mellitus (T1DM). METHODS: 230 childhood-onset diabetic patients (177 pre-pubertal), aged 7.0±3.8years followed for at least 15years after their diagnosis, were enrolled. Clinical and laboratory data at diagnosis, and C-peptide levels in a subset of patients, were compared with the severity of retinopathy and nephropathy, after a mean of 19.6±3.8years of disease. Digital retinal photographs were taken in all patients, and centrally graded. Repeated measurements of HbA1c and microalbuminuria for the whole duration of diabetes were collected in over half of the cases. RESULTS: Out of 230 patients, those with the lowest age at diagnosis had the most severe DKA and clinical conditions (p<0.05), and lower C-peptide levels (p<0.0001) at diagnosis. There was a significant relationship between pH and clinical severity (r=-0.783, p<0.0001), and between pH and C-peptide levels (r=0.278, p<0.05). The severity of ketoacidosis had no relationship with subsequent lifetime HbA1c values and long-term microvascular complications. In logistic regression analysis, the only variables that independently influenced severity of retinopathy were lifetime HbA1c (B=0.838, p<0.001), duration of disease (B=0.208, p<0.005) and age at diagnosis (B=0.116, p<0.05). CONCLUSIONS: The degree of metabolic derangement at diagnosis is not associated with retinopathy and nephropathy in childhood-onset T1DM. Age at diagnosis seems to be an important variable to be considered when evaluating the long-term effects of residual beta-cell function.

Zinc transporter 8 and MAP3865c homologous epitopes are recognized at T1D onset in Sardinian children.

Our group has recently demonstrated that Mycobacterium avium subspecies paratuberculosis (MAP) infection significantly associates with T1D in Sardinian adult patients. Due to the potential role played by MAP in T1D pathogenesis, it is relevant to better characterize the prevalence of anti-MAP antibodies (Abs) in the Sardinian population, studying newly diagnosed T1D children. Therefore, we investigated the seroreactivity against epitopes derived from the ZnT8 autoantigen involved in children at T1D onset and their homologous sequences of the MAP3865c protein. Moreover, sera from all individuals were tested for the presence of Abs against: the corresponding ZnT8 C-terminal region, the MAP specific protein MptD, the T1D autoantigen GAD65 and the T1D unrelated Acetylcholine Receptor. The novel MAP3865c281-287 epitope emerges here as the major C-terminal epitope recognized. Intriguingly ZnT8186-194 immunodominant peptide was cross-reactive with the homologous sequences MAP3865c133-141, strengthening the hypothesis that MAP could be an environmental trigger of T1D through a molecular mimicry mechanism. All eight epitopes were recognized by circulating Abs in T1D children in comparison to healthy controls, suggesting that these Abs could be biomarkers of T1D. It would be relevant to investigate larger cohorts of children, followed over time, to elucidate whether Ab titers against these MAP/Znt8 epitopes wane after diagnosis.

Genetic loci linked to type 1 diabetes and multiple sclerosis families in Sardinia.

BACKGROUND: The Mediterranean island of Sardinia has a strikingly high incidence of the autoimmune disorders Type 1 Diabetes (T1D) and Multiple Sclerosis (MS). Furthermore, the two diseases tend to be co-inherited in the same individuals and in the same families. These observations suggest that some unknown autoimmunity variant with relevant effect size could be fairly common in this founder population and could be detected using linkage analysis. METHODS: To search for T1D and MS loci as well as any that predispose to both diseases, we performed a whole genome linkage scan, sequentially genotyping 593 microsatellite marker loci in 954 individuals distributed in 175 Sardinian families. In total, 413 patients were studied; 285 with T1D, 116 with MS and 12 with both disorders. Model-free linkage analysis was performed on the genotyped samples using the Kong and Cox logarithm of odds (LOD) score statistic. RESULTS: In T1D, aside from the HLA locus, we found four regions showing a lod-score > or =1; 1p31.1, 6q26, 10q21.2 and 22q11.22. In MS we found three regions showing a lod-score > or =1; 1q42.2, 18p11.21 and 20p12.3. In the combined T1D-MS scan for shared autoimmunity loci, four regions showed a LOD >1, including 6q26, 10q21.2, 20p12.3 and 22q11.22. When we typed more markers in these intervals we obtained suggestive evidence of linkage in the T1D scan at 10q21.2 (LOD = 2.1), in the MS scan at 1q42.2 (LOD = 2.5) and at 18p11.22 (LOD = 2.6). When all T1D and MS families were analysed jointly we obtained suggestive evidence in two regions: at 10q21.1 (LOD score = 2.3) and at 20p12.3 (LOD score = 2.5). CONCLUSION: This suggestive evidence of linkage with T1D, MS and both diseases indicates critical chromosome intervals to be followed up in downstream association studies.