Background and objectives: Based on previous studies revealing acid-suppression medication as a risk factor for food allergy tolerance induction, we aimed to establish the importance of those findings in patients undergoing oral immunotherapy (OIT).Materials and methods, results: We describe a case series of four patients who underwent milk OIT with a concomitant use of proton pump inhibitor (PPI) medication and who developed anaphylaxis after a known, previously tolerated dose of milk.Conclusions: PPIs may act as a cofactor in patients undergoing OIT, triggering adverse reac-tions, irrespective of the PPI used or the dosage. It would be necessary to separate the admin-istration of drug from food intake.Since OIT is a new form of treatment, long-term adverse events arising from PPI treatment and other possible triggers are still uncertain. Consequently, monitoring of patient must be prolonged over time. Additional investigations on the influence of different drugs in OIT main-tenance phase are required.

Urea cycle disorders (UCD) are inborn errors of metabolism caused by deficiency of enzymes required to convert nitrogen from ammonia into urea. Current paradigms of treatment focus on dietary manipulations, ammonia scavenger drugs, and liver transplantation. The aim of this study was to describe the characteristics and indication of liver transplantation in UCD in a tertiary hospital. We performed a retrospective study of children with UCD seen in the period 2000–2021. Data was collected on clinical onset, hyperammonemia severity, evolution and liver transplantation. There were 33 patients in the study period, whose diagnosis were: ornithine transcarbamylase (OTC, n = 20, 10 females), argininosuccinate synthetase (ASS, n = 6), carbamylphosphate synthetase 1 (CPS1, n = 4), argininosuccinate lyase (ASL, n = 2) and N-acetylglutamate synthetase (NAGS, n = 1) deficiency. Thirty one were detected because of clinical symptoms (45% with neonatal onset). The other 2 were diagnosed being presymptomatic, by neonatal/family screening. Neonatal forms (n = 14) were more severe, all of them presented during the first week of life as severe hyperammonemia (mean peak 1,152 µmol/L). Seven patients died (6 at debut) and all survivors received transplantation. There was no mortality among the late forms. Of the 27 patients who did not die in the neonatal period, 16 (59%) received liver transplantationwith 100% survival, normal protein tolerance and usual need of citrulline supplementation. The transplant's metabolic success was accompanied by neurologic sequelae in 69%, but there was no progression of brain damage. Decision of continuous medical treatment in 11 patients appeared to be related with preserved neurodevelopment and fewer metabolic crises.

No abstract

To the Editor, Oral immunotherapy (OIT) may be regarded as an alternative to elimination diet in patients with IgE-mediated allergy. Multiple studies show OIT can induce desensitization or even sustained unresponsiveness. However, the process does not come without risks.