Harderoporphyria arises from biallelic CPOX gene mutations, leading to coproporphyrinogen oxidase deficiency in the inner mitochondrial membrane. The impact of CPOX gene mutations on adrenal function remains poorly understood. Characterizing primary adrenal insufficiency (PAI) in 2 siblings with harderoporphyria. Clinical data were recorded, and genetic analysis was performed by whole genome sequencing (WGS). Plasma steroids and urinary porphyrins were measured by liquid chromatography-mass spectrometry and high-performance liquid chromatography, respectively. Mitochondrial function was assessed using the mitochondrial membrane potential (MMP) assay in peripheral blood mononuclear cells. Patients were diagnosed with PAI at 4.5 years (P1, 46,XY) and 7 months (P2, 46,XX). P1 had atypical genitalia and developed primary gonadal insufficiency and non-immune diabetes at ages 6 and 10, respectively. Both patients had a history of microcytic anaemia, haemolysis, cholestasis, hepatosplenomegaly in early infancy, hyperpigmentation, abdominal pain, nystagmus, optic atrophy, and mild lactic acidosis in early childhood. WGS revealed a homozygous c.83_85del, p.S28* variant in CPOX. Oxidative damage to mitochondria was shown by decreased MMP in patients compared with controls (P < .0001). Hormonal assessment indicated severe PAI, suggestive of combined CYP11A1 and CYP11B1 deficiency. CPOX gene mutations cause a mixed model of PAI, affecting mitochondrial steroidogenic enzymes. Clinical manifestations of harderoporphyria may overlap with PAI signs.

A 78-year-old man with a history of neonatal anemia and jaundice and life-long photosensitivity was found to have harderoporphyria, as evidenced by increased porphyrins in urine, plasma, erythrocytes and feces including large amounts of harderoporphyrin in feces and erythrocytes. Two previously undescribed coproporphyrinogen oxidase (CPOX) mutations were identified, including a deletion of four amino acids in a region of the enzyme mutated in 7 of the 8 previously reported cases. This case increases the molecular heterogeneity of this rare porphyria, and illustrates that it should be considered as a cause of chronic photosensitivity and porphyrin elevation at any age.

The porphyrias are a group of metabolic disorders resulting from an innate abnormality in haem biosynthesis, and the clinical settings of which vary according to the genetic enzyme abnormality in question. These are genetic disorders with autosomal dominant or recessive inheritance of varying penetrance, and whose clinical expression differs according to the preferential location of haem precursors. Different classifications have been proposed according to genetic inheritance, the enzyme anomaly at issue, and clinical expression. The clinical classification distinguishes between acute porphyria (acute intermittent porphyria, porphyria variegata, hereditary coproporphyria), bullous cutaneous porphyrias (porphyria cutanea tarda, porphyria variegata and hereditary coproporphyria), painful photosensitive acute cutaneous porphyrias (erythropoietic protoporphyria and X-linked dominant protoporphyria), and rare recessive porphyrias (congenital erythropoietic porphyria, Doss porphyria, hepatoerythropoietic porphyria and harderoporphyria). Treatment depends on the clinical expression of the disorder.