A RARE CAUSE OF NEONATAL SALT WASTING: CLINICAL MANAGEMENT OF A CASE WITH PSEUDOHYPOALDOSTERONISM DETECTED WITH A NOVEL HOMOZYGOUS VARIANT IN THE SCNN1A GENE.

Introduction: Pseudohypoaldosteronism (PHA) is a rare condition that can lead to life-threatening hyperkalemia, cardiac arrest and death if not rapidly recognised and treated. Systemic PHA results from the inactivation of variants in genes encoding subunits of the epithelial sodium channel (ENaC). Frequent dose revision is required in oral replacement therapy in patients with systemic PHA. This condition requires a lifelong close follow-up and treatment process in patients. Case Description: In this study, we present the clinical follow-up of a newborn diagnosed with PHA who presented at 9 days of age with severe dehydration, malnutrition, vomiting and lethargy. A novel pathogenic homozygous mutation, c.1536C>A p.(Tyr512*), was identified in exon 11 of the SCNN1A gene. Discussion: Systemic PHA is a rare, life-threatening disorder that may be misdiagnosed in early infancy. Our case highlights a severe systemic presentation associated with ENaC dysfunction. Reporting the clinical course together with genetic findings may improve recognition of severe phenotypes, support earlier diagnosis, and contribute to a better understanding of genotype-phenotype relationships in systemic PHA. Conclusion: Neonates with hyperkalemia and hyponatremia should prompt suspicion of PHA and early aggressive treatment; this case highlights severe systemic PHA and the importance of combined clinical and genetic evaluation.