PALB2 mutations in European familial pancreatic cancer families

Slater EP, Langer P, Niemczyk E, Strauch K, Butler J, Habbe N, Neoptolemos JP, Greenhalf W, Bartsch DK. PALB2 mutations in European pancreatic cancer families. Recently, PALB2 was reported to be a new pancreatic cancer susceptibility gene as determined by exomic sequencing, as truncating PALB2 mutations were identified in 3 of 96 American patients with familial pancreatic cancer (FPC). Representing the European Registry of Hereditary Pancreatitis and Familial Pancreatic Cancer (EUROPAC) and the German National Case Collection for Familial Pancreatic Cancer (FaPaCa), we evaluated whether truncating mutations could also be detected in European FPC families. We have directly sequenced the 13 exons of the PALB2 gene in affected index patients of 81 FPC families. An index patient was defined as the first medically identified patient, stimulating investigation of other members of the family to discover a possible genetic factor. None of these patients carried a BRCA2 mutation. We identified three (3.7%) truncating PALB2 mutations, each producing different stop codons: R414X, 508‐9delAG and 3116delA. Interestingly, each of these three families also had a history of breast cancer. Therefore, PALB2 mutations might be causative for FPC in a small subset of European families, especially in those with an additional occurrence of breast cancer.     

Efficacy and safety of deferasirox doses of >30 mg/kg per d in patients with transfusion-dependent anaemia and iron overload

The highest approved dose of deferasirox is currently 30 mg/kg per d in many countries; however, some patients require escalation above 30 mg/kg per d to achieve their therapeutic goals. This retrospective analysis investigated the efficacy (based on change in serum ferritin levels) and safety of deferasirox >30 mg/kg per d in adult and paediatric patients with transfusion-dependent anaemias, including β-thalassaemia, sickle cell disease and the myelodysplastic syndromes. In total, 264 patients pooled from four clinical trials received doses of >30 mg/kg per d; median exposure to deferasirox >30 mg/kg per d was 36 weeks. In the overall population there was a statistically significant median decrease in serum ferritin of 440 μg/l ( P  < 0·0001) from pre-dose-escalation to the time-of-analysis; significant decreases were also observed in adult and paediatric patients, as well as β-thalassaemia patients. The adverse event profile in patients who received deferasirox doses of >30 mg/kg per d was consistent with previously published data. There was no worsening of renal or liver function following dose escalation. Deferasirox >30 mg/kg per d effectively reduced iron burden to levels lower than those achieved prior to dose escalation in patients with transfusion-dependent anaemias. This has important implications for patients who are heavily transfused and may require higher doses to reduce body iron burden.     

Pulmonary hypertension in thalassaemia major patients with normal left ventricular systolic function

Pulmonary hypertension is common in adults with thalassaemia and other haemolytic anaemias. It was hypothesised that regular transfusions in thalassaemia major should both decrease the chronic haemolytic rate and be protective from pulmonary hypertension (PHT). To reduce the contribution of existing cardiac disease to PHT, the subjects were limited to patients with normal left ventricular shortening fractions. Associations with multiple laboratory markers of haemolysis, serum ferritin levels, chest X-rays findings and splenectomy status were also considered. We found no biochemical, transfusional, or clinical (except gender) differences in transfused thalassaemia patients with or without pulmonary hyper tension.     

Liver ferritin subunit ratios in neonatal hemochromatosis

Neonatal hemochromatosis is an enigmatic disease. Little is known about iron metabolism in this disease, including the tissue concentration of ferritin or its H and L subunit ratio. The authors report the tissue iron, ferritin, and ferritin subunit content of a child who died at 5 weeks of neonatal hemochromatosis. The child was born at 29 weeks gestation to a mother with lupus, sickle cell trait, and gestational diabetes. The child's severe liver dysfunction led to the clinical diagnosis of neonatal hemochromatosis at 1 week of age. Despite aggressive support, including red cell transfusions and chelation, the child died of an intracranial hemorrhage. Autopsy showed liver fibrosis and iron staining characteristic of neonatal hemochromatosis. Autopsy liver tissue was compared to age-matched control tissue. Soluble protein was analyzed by the Bradford method. Soluble iron (over 90% of total iron) was analyzed by the o -phenanthroline complex. Tissue ferritin and human ferritin controls (Calzyme) were analyzed by Western blotting after SDS-PAGE, identified with sheep anti-human ferritin antibodies (The BindingSite) secondary antibody-fluorescence for detection, and quantified using the Molecular Dynamics Storm 840 phosphorimager and ImageQuant software. Protein, iron, and total ferritin were similar in the normal and neonatal hemochromatosis liver tissues. Ferritin subunits, however, showed an increased H/L-subunit ratio compared to an age-matched control. This first report of a marked increase in the ferritin H/L-subunit ratio may point to an underlying mechanism of disease in this enigmatic disorder.     

Mutations of the flavin-containing monooxygenase gene (FMO3) cause trimethylaminuria, a defect in detoxication

Individuals with the recessive condition trimethylaminuria exhibit variation in metabolic detoxication of xenobiotics by hepatic flavin- containing monooxygenases. We show here that mutations in the human flavin-containing monooxygenase isoform 3 gene ( FMO3 ) impair N - oxygenation of xenobiotics and are responsible for the trimethylaminuria phenotype. Three disease-causing mutations in nine Australian-born probands have been identified which share a particular polymorphic haplotype. Nonsense and missense mutations are associated with a severe phenotype and are also implicated in impaired metabolism of other nitrogen- and sulfur-containing substrates including biogenic amines, both clinically and when mutated proteins expressed from cDNA are studied in vitro . These findings illustrate the critical role played by human FMO3 in the metabolism of xenobiotic substrates and endogenous amines.      

Safety of hydroxyurea in children with sickle cell anemia: results of the HUG-KIDS study, a phase I/II trial. Pediatric Hydroxyurea Group.

Previous studies have determined the short-term toxicity profile, laboratory changes, and clinical efficacy associated with hydroxyurea (HU) therapy in adults with sickle cell anemia. The safety and efficacy of this agent in pediatric patients with sickle cell anemia has not been determined. Children with sickle cell anemia, age 5 to 15 years, were eligible for this multicenter Phase I/II trial. HU was started at 15 mg/kg/d and escalated to 30 mg/kg/d unless the patient experienced laboratory toxicity. Patients were monitored by 2-week visits to assess compliance, toxicity, clinical adverse events, growth parameters, and laboratory efficacy associated with HU treatment. Eighty-four children were enrolled between December 1994 and March 1996. Sixty-eight children reached maximum tolerated dose (MTD) and 52 were treated at MTD for 1 year. Significant hematologic changes included increases in hemoglobin concentration, mean corpuscular volume, mean corpuscular hemoglobin, and fetal hemoglobin parameters, and decreases in white blood cell, neutrophil, platelet, and reticulocyte counts. Laboratory toxicities typically were mild, transient, and were reversible upon temporary discontinuation of HU. No life-threatening clinical adverse events occurred and no child experienced growth failure. This Phase I/II trial shows that HU therapy is safe for children with sickle cell anemia when treatment was directed by a pediatric hematologist. HU in children induces similar laboratory changes as in adults. Phase III trials to determine if HU can prevent chronic organ damage in children with sickle cell anemia are warranted.     

Variability in hepatic iron concentration in percutaneous needle biopsy specimens from patients with transfusional hemosiderosis

In patients with sickle cell disease or beta-thalassemia receiving RBC transfusions for a long period, a precise knowledge of the liver iron concentration (LIC) is essential for treatment. Patients underwent LIC and liver pathology assessment by duplicate biopsies in 2 passes from the same local liver site. Fresh tissue cores in trace element-free containers and tissues from dissolved paraffin-embedded cores were analyzed. LIC measurements in each of 2 paraffin-embedded cores did not differ significantly (median, 12,455 vs 12,153 microg/g dry weight; n = 29). A significant difference was observed when 1 fresh tissue sample and 1 paraffin-embedded core were analyzed (median, 11,716 vs 12,864 microg/g dry weight; n = 16; P < .001) with a median disagreement between LIC measurements of 23.0%. We found high agreement in LICs between liver biopsy specimens processed by the paraffin-embedding technique but overestimation of LICs in comparison with desiccated fresh tissue samples.