Thrombotic thrombocytopenic purpura (TTP) is a life-threatening systemic illness of abrupt onset and unknown cause. Proteolysis of the blood-clotting protein von Willebrand factor (VWF) observed in normal plasma is decreased in TTP patients. However, the identity of the responsible protease and its role in the pathophysiology of TTP remain unknown. We performed genome-wide linkage analysis in four pedigrees of humans with congenital TTP and mapped the responsible genetic locus to chromosome 9q34. A predicted gene in the identified interval corresponds to a segment of a much larger transcript, identifying a new member of the ADAMTS family of zinc metalloproteinase genes (ADAMTS13). Analysis of patients' genomic DNA identified 12 mutations in the ADAMTS13 gene, accounting for 14 of the 15 disease alleles studied. We show that deficiency of ADAMTS13 is the molecular mechanism responsible for TTP, and suggest that physiologic proteolysis of VWF and/or other ADAMTS13 substrates is required for normal vascular homeostasis.

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CUTE CHEST SYNDROME AND painful episodes are the most common precedents of death in adults with sickle cell anemia (SCA). 1 A randomized, doubleblinded, placebo-controlled trial, the

VCP plus XRT is a superior adjuvant combination compared with 8-in-1 chemotherapy plus XRT. For patients with M0 tumors, residual tumor bulk (not extent of resection) is a predictor for PFS. Patients with M0 tumors, > or = 3 years with < or = 1.5 cm2 residual tumor, had a 78%+/-6% 5-year PFS rate. Children younger than 3 years old who received a reduced XRT dosage had the lowest survival rate.

A randomized, controlled clinical trial established the efficacy and safety of short-term use of hydroxyurea in adult sickle cell anemia. To examine the risks and benefits of long-term hydroxyurea usage, patients in this trial were followed for 17.5 years during which they could start or stop hydroxyurea. The purpose of this follow-up was to search for adverse outcomes and estimate mortality. For each outcome and for mortality, exact 95% confidence intervals were calculated, or tests were conducted at a 5 0.05 level (P-value <0.05 for statistical significance). Although the death rate in the overall study cohort was high (43.1%; 4.4 per 100 person-years), mortality was reduced in individuals with long-term exposure to hydroxyurea. Survival curves demonstrated a significant reduction in deaths with long-term exposure. Twenty-four percent of deaths were due to pulmonary complications; 87.1% occurred in patients who never took hydroxyurea or took it for <5 years. Stroke, organ dysfunction, infection, and malignancy were similar in all groups. Our results, while no longer the product of a randomized study because of the ethical concerns of withholding an efficacious treatment, suggest that long-term use of hydroxyurea is safe and might decrease mortality. Am. J. Hematol. 85:403-408, 2010. V

Monogenic deficiency diseases provide unique opportunities to define the contributions of individual molecules to human physiology and to identify pathologies arising from their dysfunction. Here we describe a deficiency disease in two human siblings that presented with severe bleeding, frequent infections and osteopetrosis at an early age. These symptoms are consistent with but more severe than those reported for people with leukocyte adhesion deficiency III (LAD-III). Mechanistically, these symptoms arose from an inability to activate the integrins expressed on hematopoietic cells, including platelets and leukocytes. Immortalized lymphocyte cell lines isolated from the two individuals showed integrin activation defects. Several proteins previously implicated in integrin activation, including Ras-associated protein-1 (RAP1) 1 and calcium and diacylglycerol-regulated guanine nucleotide exchange factor-1 (CALDAG-GEF1) 2 , were present and functional in these cell lines. The genetic basis for this disease was traced to a point mutation in the coding region of the KINDLIN3 (official gene symbol FERMT3) gene 3 . When wild-type KINDLIN-3 was expressed in the immortalized lymphocytes, their integrins Correspondence should be addressed to T.V.B. (byzovat@ccf.org). 6 These authors contributed equally to this work.Note: Supplementary information is available on the Nature Medicine website. AUTHOR CONTRIBUTIONS N.L.M. identified the Kindlin-3 mutation, performed molecular biology and protein biochemistry studies and wrote the manuscript; L.Z. contributed to study design and experiments on primary leukocytes from subjects; J.C. performed assays with EGFP-Kindlin-3 rescue and siRNA-mediated KINDLIN3 knockdown and western blotting; A.C. performed microscopy studies and FACS analysis; O.R. performed cell culture work and molecular biology; Y.-Q.M. performed molecular biology and Kindlin-3-specific antibody preparation; E.A.P. performed platelet studies; M.T. performed neutrophil analysis; D.P.L. and A.I.C. performed osteogenesis assays; S.B.S. originally described the subjects, designed clinical studies and wrote the manuscript; E.F.P. designed the studies, interpreted the results and wrote the manuscript; T.V.B. performed experiments with platelets and leukocytes, designed the general strategy, interpreted data and wrote the manuscript. Kindlin-3 is one of the three-member kindlin family of intracellular proteins that are linked to the actin cytoskeleton 3 . The family is evolutionarily conserved with an ortholog, UNC-112, found in Caenorhabditis elegans 4 . Each kindlin contains a C-terminal FERM domain that is most similar to that of talin, another cytoskeletal protein involved in integrin regulation. Kindlins and talin bind to nonoverlapping sites in the cytoplasmic tails of integrins 5 . Kindler disease, associated with a deficiency of Kindlin-1, has multiple symptoms, including skin blistering and poikiloderma 6 . Kindlin-2 deficiency is embryonically lethal in zebrafish and mice but has not been described in hu...

Fatal T-cell lymphomas developed in three patients with a chronic illness manifested by fever, pneumonia, dysgammaglobulinemia, hematologic abnormalities, and extraordinarily high titers of antibody to the Epstein-Barr virus (EBV) capsid antigen (greater than 10,000) and early antigen (greater than 640) but low titers to the EBV nuclear antigen (less than or equal to 40). To understand the pathogenesis of these tumors better, we determined the immunophenotype of the tumor cells and analyzed tumor-cell DNA for EBV genomes and for lymphoid-cell gene rearrangements. More than 80 percent of the cells in tumors had an activated helper T-cell phenotype (T4, T11, la positive). The EBV genome was found by in situ hybridization in tumor tissue from each patient. Southern blot assay of DNA digests from one patient showed the same pattern as that of the EBV-infected marmoset line, B95-8. DNA digests from two patients showed a monoclonal proliferation of T cells determined on the basis of uniform T-cell-receptor gene rearrangements and a single band for the joined termini of the EBV genome. We conclude that EBV may infect T cells and contribute to lymphomas in selected patients with severe EBV infections.

While this diet does not replace conventional antineoplastic treatments, these preliminary results suggest a potential for clinical application which merits further research.