Role of the C1858T polymorphism of protein tyrosine phosphatase non-receptor type 22 (PTPN22) in children and adolescents with type 1 diabetes.

In recent years, increasing interest has been devoted to the susceptibility gene polymorphisms in type 1 diabetes (T1D) as well as in other autoimmune diseases. Among these, a nucleotide polymorphism of the gene encoding for the protein tyrosine phosphatase non-receptor type 22 (PTPN22) has been associated with T1D in several studies. The aim of this study is to define the frequency of the C1858T polymorphism in the PTPN22 gene in a cohort of 113 Caucasian patients (58 males and 55 females) with T1D, and to assess a possible correlation with a group of clinically relevant variables: age at onset, gender, diabetes-related autoantibodies, residual ß-cell function and daily insulin requirement (IR) 6 months after diagnosis. Using a PCR-RFLP approach, we evidenced a 17.7% frequency of the PTPN22 C1858T polymorphism in diabetic patients, higher than the frequency showed in the general population. A statistically significant correlation between this polymorphism and higher levels of C-peptide at diagnosis and lower IR at 6 months from diagnosis was observed (P=0.001 and P=0.04). Moreover, 1858T variant carriers were more frequently positive for glutamic acid decarboxylase (GAD) autoantibodies at diagnosis than wild-type subjects (P=0.19). On the other hand, no significant difference regarding age at onset, gender distribution, insulinoma-associated 2 molecule (IA2) and islet cell antibodies (ICA) positivity was found. These findings, if adequately confirmed in the future and extended to larger samples, may characterize a subset of T1D patients with a defined genetic pattern, who may be eligible for trials aimed to preserve residual ß-cell function in the coming years.

Airway hyper-responsiveness to mannitol provides a good evaluation of atopy in childhood asthma.

AIM: The relationship between airway hyper-responsiveness (AHR) and atopy has been previously investigated, but there are still some issues to be clarified. The aim of this study was to assess the link between AHR and mannitol and atopy in asthmatic children. METHODS: We evaluated 44 children with asthma, aged 6-16 years of age, using skin prick tests (SPTs), serum total and specific immunoglobulin E (IgE) levels and the mannitol challenge test (MCT). RESULTS: We found a good correlation between AHR to mannitol and specific IgE against Dermatophagoides pteronissinus (r = -0.66, p < 0.001) and a weak correlation with specific IgE against dog dander (r = -0.33, p = 0.01) and Aspergillus fumigatus (r = -0.23, p = 0.02). Furthermore, we found a weak correlation between AHR to mannitol and serum total IgE (r = -0.30; p = 0.03), the sum of specific IgE to aeroallergens (r = -0.37, p = 0.01) and the number of positive SPTs (r = -0.31, p = 0.02). CONCLUSION: Measuring AHR with MCT might provide an accurate evaluation of the degree of atopy in children. The patients with a higher degree of atopy were significantly more reactive to mannitol. In clinical practice, these results indicate that children with asthma who are more atopic may require more intensive treatment strategies to reduce AHR.

Usefulness of Atopy Patch Test on a child with milk protein-induced enterocolitis syndrome: a case report.

We describe the case of a child affected by milk-protein induced enterocolitis, in which oral challenge with corn was performed without symptoms after a negative specific Atopy Patch Test. Food protein-induced enterocolitis syndrome (FPIES) is an uncommon nonIgE-mediated gastrointestinal food hypersensitivity of infancy, characterized by severe vomiting and diarrhea arising within 1 to 3 hours after ingestion of the causative food. Little is known about the pathophysiology of FPIES. The absence of food-specific IgE as demonstrated by negative skin prick tests suggests that the disease is not caused by an early onset IgE-mediated reaction. Atopy Patch Test has been described as sensitive and predictive in this syndrome. The hypothesis on the immunological pathogenesis has been discussed on the basis of literature data.