Heme oxygenase-1 deficiency as an extremely rare cause of AA-type renal amyloidosis: Expanding the clinical features and review of the literature

Heme oxygenase-1 (HMOX-1) is an enzyme that regulates heme degradation. Antiinflammatory, antioxidant, and cytoprotective effects of HMOX-1 were also described. It is encoded by the HMOX1 gene, and biallelic mutations cause HMOX-1 deficiency, which is a rare chronic multisystemic inflammatory disorder. This inflammatory status could lead to the development of secondary AA-type amyloidosis theoretically. Here, we report a 30-year-old male with AA-type renal amyloidosis due to a chronic inflammatory condition of unknown origin. Paternal consanguinity and dysmorphic features raised suspicion of a rare genetic disorder. Clinical exome sequencing (CES) confirmed the HMOX-1 deficiency diagnosis related to homozygous missense G139V mutation. To the best of our knowledge, our patient is the eleventh HMOX-1 deficiency case in the literature. Also, HMOX-1 deficiency-related systemic AA-type amyloidosis has not been reported before.

Automated summary

In this study, we report a case of AA-type renal amyloidosis in a young male, which was caused by a chronic inflammatory condition possibly due to HMOX-1 deficiency. Clinical exome sequencing confirmed the diagnosis of HMOX-1 deficiency related to a homozygous missense G139V mutation. To the best of our knowledge, this is the eleventh case of HMOX-1 deficiency reported in the literature and the first report of HMOX-1 deficiency-related systemic AA-type amyloidosis.