Copper therapy reduces intravascular hemolysis and derepresses ferroportin in mice with mosaic mutation (Atp7amo-ms): An implication for copper-mediated regulation of the Slc40a1 gene expression.

Mosaic mutant mice displaying functional dysfunction of Atp7a copper transporter (the Menkes ATPase) are an established animal model of Menkes disease and constitute a convenient tool for investigating connections between copper and iron metabolisms. This model allows to explore changes in iron metabolism in suckling mutant mice suffering from systemic copper deficiency as well as in young and adult ones undergone copper therapy, which reduces lethal effect of the Atp7a gene mutation. Our recent study demonstrated that 14-day-old mosaic mutant males display blood cell abnormalities associated with intravascular hemolysis, and show disturbances in the functioning of the hepcidin-ferroportin regulatory axis, which controls systemic iron homeostasis. We thus aimed to check whether copper supplementation recovers mutants from hemolytic insult and rebalance systemic iron regulation. Copper supplementation of 14-day-old mosaic mutants resulted in the reestablishment of hematological status, attenuation of hepicidin and concomitant induction of the iron exporter ferroportin/Slc40a1 expression in the liver, down-regulated in untreated mutants. Interestingly, treatment of wild-type males with copper, induced hepcidin-independent up-regulation of ferroportin protein level in hepatic macrophages in both young and adult (6-month-old) animals. Stimulatory effect of copper on ferroportin mRNA and protein levels was confirmed in bone marrow-derived macrophages isolated from both wild-type and mosaic mutant males. Our study indicates that copper is an important player in the regulation of the Slc40a1 gene expression.

Causes of hemolysis in neonates with extreme hyperbilirubinemia.

OBJECTIVE: We instituted a quality improvement process to enhance our capacity to diagnose genetic hemolytic conditions in neonates with extreme hyperbilirubinemia. STUDY DESIGN: During a 1-year period, whenever the total serum bilirubin (TSB) was >25 mg dl(-1) a special evaluation was performed. If we deemed an erythrocyte membrane defect likely, based on red blood cell morphology, EMA-flow cytometry was performed. Otherwise 'next-generation' sequencing was performed using a panel of genes involved in neonatal hyperbilirubinemia. RESULT: Ten neonates had a TSB ⩾ 25 mg dl(-1). Two others were evaluated as part of this process at the request of their attending neonatologists, because each had a TSB >14 mg dl(-1) in the first hours after birth and required phototherapy for ⩾ 1 week. Explanations for the jaundice were found in all 12 neonates. Five had hereditary spherocytosis, three of which also had ABO hemolytic disease. Two had pyruvate kinase deficiency. One had severe G6PD deficiency. The other four had ABO hemolytic disease. CONCLUSION: On the basis of the present small case series, we suggest that among neonates with extreme hyperbilirubinemia, it can be productive to pursue a genetic basis for hemolytic disease.