Objective: We reported 3 patients with primary aldosteronism who presented at times of high plasma LH, and had somatic CTNNB1 mutations causing ˜100-fold elevation of LHCGR in their APAs (Teo et al. NEJM 2015). Subsequently we identified 4 further patients, but the association with pregnancy was not found by others. Whole exome sequencing (WES) of an APA diagnosed at onset of puberty suggests an explanation.
Method: WES of tumour and blood was performed in a 12-year old boy with severe hypertension. Candidate genes were Sanger sequenced in 6 other APAs with known or suspected CTNNB1 mutations. LHCGR expression was measured in all 7 APAs by qPCR. Function of mutant genes was assessed by measurement of aldosterone production by NCI-H295R adrenocortical cells and primary human APA cells.
Results: The boys APA had S45F mutation of CTNNB1 and Q209P mutation of GNA11. Mutations of Q209, to P or H, were found in all 6 patients with previously identified mutations of CTNNB1 (S33C, S45P, T41A, G34R, or S45F). qPCR showed 32166 fold increase in expression of LHCGR in the APAs compared with the normal adjacent adrenal tissue. H295R cells (whose CTNNB1 genotype is S45P) were GNA11 wild-type. In cells transfected with CTNNB1 wild-type, aldosterone secretion fell by 51% (n=3, P<0.001). Q209P transfection increased aldosterone by 277% (n=3, P<0.05). Primary human APA cells electroporated with both GNA11 Q209H and CTNNB1 del45 group showed a twfold increase in aldosterone secretion compared to single-mutant transfected cells (n=3, P<0.01).
Conclusions: Double somatic mutations of CTNNB1 and GNA11 may be required to induce reversion to gonadal phenotype, causing LHCGR-expressing APAs to present at times of high LH. GNA11 mediates the aldosterone response to AngII, and Q209 mutations cause uveal melanomas. They are in the analogous residue to Q227 mutations of GNAS which activate cAMP in McCune Albright.