Somatic KCNJ5 mutation occurring early in adrenal development may cause a novel form of juvenile primary aldosteronism

• We report a novel type of non-familial juvenile primary aldosteronism (PA).
• Bilateral adrenals had the same pathology: normal adrenal or hyperplasia.
• Hyperplasia harbored a KCNJ5 mutation, but normal adrenal did not.
• The mutation likely arose in mesodermal development and caused genetic mosaicism.
• The type of PA can be surgically treated by combination with super-selective adrenal venous sampling.

We report a case of non-familial juvenile primary aldosteronism (PA). Super-selective adrenal venous sampling identified less aldosterone production in the right inferior adrenal segment than others. Bilateral adrenalectomy sparing the segment normalized blood pressure and improved PA. Both adrenals had similar histologies, consisting of a normal adrenal cortex and aldosterone synthase-positive hyperplasia/adenoma. An aldosterone-driving KCNJ5 mutation was detected in the lesions, but not in the histologically normal cortex. After taking into account that the two adrenal glands displayed a similar histological profile, as well as the fact that hyperplastic lesions in both glands exhibited a common KCNJ5 mutation, we conclude that the specific mutation may have occurred at an adrenal precursor mesodermal cell, at an early stage of development; its daughter cells were mixed with non-mutant cells and dispersed into both adrenal glands, resulting into a form of the condition known as genetic mosaicism.