Molecular analysis of the CYP11B2 gene in 62 patients with Hypoaldosteronism due to Aldosterone Synthase Deficiency.

CONTEXT Isolated congenital hypoaldosteronism presents in early infancy with symptoms including vomiting, severe dehydration, salt wasting and failure to thrive. The main causes of this rare autosomal recessive disorder are pathogenic variants of the CYP11B2 gene leading to Aldosterone Synthase Deficiency. OBJECTIVE To investigate the presence of CYP11B2 pathogenic variants in a cohort of patients with a clinical, biochemical and hormonal profile suggestive of Aldosterone Synthase Deficiency. DESIGN Clinical and molecular study. SETTING Tertiary Academic Children's Hospital, Center for Rare Pediatric Endocrine Diseases. PATIENTS AND METHODS Sixty-two patients (56 unrelated patients and 6 siblings), with hypoaldosteronism and their parents, underwent CYP11B2 gene sequencing after its selective amplification against the highly homologous CYP11B1 gene. In silico analysis of the identified novel variants was carried out in order to evaluate protein stability and potential pathogenicity. RESULTS CYP11B2 gene sequencing revealed that 62 patients carried a total of 12 different pathogenic CYP11B2 gene variants, six of which are novel. Importantly, 96% of the 56 patients carried the previously reported p.T185I variant either in homozygosity or in compound heterozygosity with another variant. The six novel variants detected were: p.M1I, p.V129M, p.R141Q, p.A165T, p.R448C and the donor splice site variant of intron 8, c.1398 + 1G>A. CONCLUSION Molecular diagnosis was achieved in 62 patients with Aldosterone synthase deficiency, the largest cohort thus far reported. Six novel genetic variants were identified as possibly pathogenic, extending the spectrum of reported molecular defects of the CYP11B2 gene.