Pseudohypoaldosteronism type 1 due to a novel mutation in the mineralocorticoid receptor gene.

Background/aims: Autosomal dominant pseudohypoaldosteronism type 1 is caused by mutations in the mineralocorticoid receptor (NR3C2) gene, often leading to life-threatening hyponatremia and hyperkalemia in the newborn period. We report a novel mutation in the NR3C2 gene, and report, for the first time, the association of well-treated pseudohypoaldosteronism with failure to thrive. This report additionally highlights the importance of aldosterone-sensitive sodium transport in the neonatal period.

Patient And Methods: The patient presented with salt loss, hyperkalemia and a mild metabolic acidosis in the neonatal period (day of life 8). Further evaluation revealed significantly elevated levels of 18-hydroxycorticosterone, aldosterone and plasma renin activity, suggesting the diagnosis of pseudohypoaldosteronism.

Results: Analysis of the patient's NR3C2 gene revealed a novel missense mutation (c.1817G>C), which was subsequently analyzed in his parents and sister. Interestingly, the patient's mother was found to have an identical mutation.

Conclusion: We report a novel mutation in the gene for the mineralocorticoid receptor and an unusual clinical course of pseudohypoaldosteronism type 1 in an adequately treated patient.