Mutation in erythroid specific transcription factor KLF1 causes Hereditary Spherocytosis in the Nan hemolytic anemia mouse model.

KLF1 regulates definitive erythropoiesis of red blood cells by facilitating transcription through high affinity binding to CACCC elements within its erythroid specific target genes including those encoding erythrocyte membrane skeleton (EMS) proteins. Deficiencies of EMS proteins in humans lead to the hemolytic anemia Hereditary Spherocytosis (HS) which includes a subpopulation with no known genetic defect. Here we report that a mutation, E339D, in the second zinc finger domain of KLF1 is responsible for HS in the mouse model Nan. The causative nature of this mutation was verified with an allelic test cross between Nan/+ and heterozygous Klf1(+/-) knockout mice. Homology modeling predicted Nan KLF1 binds CACCC elements more tightly, suggesting that Nan KLF1 is a competitive inhibitor of wild-type KLF1. This is the first association of a KLF1 mutation with a disease state in adult mammals and also presents the possibility of being another causative gene for HS in humans.

Cisplatin pharmacokinetics in a child receiving peritoneal dialysis.

Cisplatin is a highly effective and frequently used drug in the chemotherapy of solid tumors in children, but there is currently no information to guide dosing in children requiring dialysis. Here, we present the case of a 2-year-old boy with end-stage renal disease managed with peritoneal dialysis and requiring cisplatin for a newly diagnosed hepatoblastoma. A pharmacokinetic study was performed to personalize the cisplatin dose with the goal of providing adequate cisplatin exposure and avoiding excessive exposure and toxicity. Accordingly, 25% of the standard cisplatin dose was infused intravenously over 4 h. Serial blood and peritoneal fluid samples were obtained, and free cisplatin levels were subjected to noncompartmental pharmacokinetic analysis. The disposition of free cisplatin was significantly altered as compared to that of normal children. Despite a 75% dose reduction, our patient showed a fourfold increase in free cisplatin exposure (AUC = 64.1 h mcg/mL) compared with the AUC observed in children with normal kidney (15 + or - 9 h mcg/mL) function. When a subsequent dose was decreased to 8.7% of the standard dose, the free cisplatin AUC measured 29.7 h mcg/mL and more closely approximated the exposure observed in children with normal kidney function.