Focus on increased serum angiotensin-converting enzyme level: From granulomatous diseases to genetic mutations

Angiotensin I-converting enzyme (ACE) is a well-known zinc-metallopeptidase that converts angiotensin I to the potent vasoconstrictor angiotensin II and degrades bradykinin, a powerful vasodilator, and as such plays a key role in the regulation of vascular tone and cardiac function. Increased circulating ACE (cACE) activity has been reported in multiple diseases, including but not limited to granulomatous disorders. Since 2001, genetic mutations leading to cACE elevation have also been described. This review takes advantage of the identification of a novel ACE mutation (25-IVS25 + 1G > A) in two Belgian pedigrees to summarize current knowledge about the differential diagnosis of cACE elevation, based on literature review and the experience of our centre. Furthermore, we propose a practical approach for the evaluation and management of patients with elevated cACE and discuss in which cases search for genetic mutations should be considered.