Aldosterone synthase deficiency from homozygous cyp11b2 mutation presenting with salt-wasting crisis and failure to thrive in an infant

Introduction: Aldosterone synthase deficiency (ASD) is a rare autosomal recessive disorder caused by pathogenic variants in the CYP11B2 gene, leading to impaired aldosterone synthesis and life-threatening salt-wasting. We present a case of an infant with failure to thrive, dehydration, and electrolyte imbalance, diagnosed through next-generation sequencing.
Material and Methods: mitted with persistent vomiting, constipation, and a10% weight loss. Laboratory evaluation showed severe hyponatremia (116 mmol/L), hyperkalemia (6.5 mmol/L), hypochloremia (87 mmol/L), and metabolic alkalosis. Differential diagnosis included gastrointestinal loss, renal salt-wasting, cystic fibrosis, celiac disease, and congenital adrenal hyperplasia. Normal 17-hydroxyprogesterone excluded classical CAH. Next-generation sequencing was performed.
Results: A homozygous pathogenic variant c.554C>T (p.Thr185Ile) in CYP11B2 confirmed ASD. Treatment with fludrocortisone and sodium supplementation resulted in rapid correction of electrolytes and improved growth. Follow-up at 3.5 years showed normal growth (14.5 kg, 103 cm), stable electrolytes, and normal development, with only mild transient hyponatremia during illness.
Conclusion: ASD should be considered in infants with vomiting, dehydration, and combined hyponatremia–hyperkalemia when CAH is excluded. Early diagnosis and mineralocorticoid therapy prevent complications and support normal development.
Key words: aldosterone synthase deficiency; CYP11B2; infant; hyperkalemia; hyponatremia; fludrocortisone.