The appearance of hereditary coproporphyria (HCP) before puberty is very rare, and all reported cases of early-onset HCP have been in the homozygous or the compound heterozygous state. Some have been identified as harderoporphyria, which is a rare erythropoietic variant form of HCP. These conditions can be differentiated by molecular analysis because the gene abnormality responsible for harderoporphyria seems to be unique (K404E IntroductionHereditary coproporphyria (HCP) is a hereditary autosomaldominant disease of heme biosynthesis resulting from a partial deficiency of coproporphyrinogen oxidase (CPO). It is clinically characterized by neurologic dysfunction attacks and occasional photosensitivity. 1 HCP is rare before puberty, 2 and all reported early-onset cases have been in the homozygous 3-8 or the compound heterozygous state. 9 Harderoporphyria, a rare erythropoietic variant form of HCP, is characterized by neonatal hyperbilirubinemia and hemolytic anemia, hepatosplenomegaly, and sometimes photosensitivity. 6-9 To date, 3 families with harderoporphyria have been reported. Molecular analysis indicates that a CPO gene abnormality, K404E, was unique for the disease. 9 Therefore, HCP can be differentially diagnosed from harderoporphyria by both clinical and laboratory examinations and molecular analysis. Here, we describe a first case of neonatal-onset HCP in the heterozygous state with male pseudohermaphrodism. Study design Patient historyThe patient was born at term to healthy, nonconsanguineous Japanese parents with no family history of porphyria. Perinatal history was normal. The amniotic fluid and placenta were yellow, as occurred in a patient with congenital erythropoietic porphyria (CEP). 10 Shortly after birth, the infant was admitted to our hospital for tachypnea and severe jaundice. He displayed icteric skin, petechiae, hypotonia, lethargy, and marked hepatosplenomegaly. Laboratory data showed hypoglycemia (22 mg/dL blood sugar), thrombocytopenia (93 000/L platelets), and anemia (9.4 g/dL erythrocytes) with marked erythroblastosis (26 900/L erythroblasts), similar to what was seen in a patient with CEP. 11 Erythrocyte morphology showed some dacryocytes, leptocytes, and echinocytes. Based on these findings, his anemia was concluded to be hemolytic. Total serum bilirubin level was 14.16 mg/dL (indirect, 6.64 mg/dL). Respiratory distress and hypotonia were improved after intravenous glucose loading for hypoglycemia. Phototherapy was performed for hyperbilirubinemia to avert kernicterus on days 1 and 2. Soon afterward, the patient showed partial edema with vesicles and bulla. After his incubator was wrapped with UV cut-off film, no new skin lesions appeared. The severe hemolytic state, erythroblastosis, and morphologic abnormalities of erythrocyte disappeared, and partial regression of hepatosplenomegaly was observed in a few weeks. In the first week after birth, dark-brown urine was observed. Porphyrins were detected using reverse-phase high-performance liquid-chromatography. 12 He also had ambiguous...

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