Widely used as anti-cancer and immunosuppressive agents, thiopurines have narrow therapeutic indices due to frequent toxicities, partly explained by TPMT genetic polymorphisms. Recent studies identified germline NUDT15 variation as another critical determinant of thiopurine intolerance, but the underlying molecular mechanisms and its clinical implications remain unknown. In 270 children enrolled in clinical trials for acute lymphoblastic leukemia in Guatemala, Singapore, and Japan, we identified 4 NUDT15 coding variants (p.Arg139Cys, p.Arg139His, p.Val18Ile, p.Val18_Val19insGlyVal) that resulted in 74.4%–100% loss of nucleotide diphosphatase activity. Loss-of-function NUDT15 diplotypes were consistently associated with thiopurine intolerance across three cohorts (P=0.021, 2.1×10−5, and 0.0054, respectively; meta-analysis P=4.45×10−8, allelic effect size=−11.5). Mechanistically, NUDT15 inactivated thiopurine metabolites and decreased its cytotoxicity in vitro, and patients with defective NUDT15 alleles showed excessive thiopurine active metabolites and toxicity. Taken together, our results indicate that a comprehensive pharmacogenetic model integrating NUDT15 variants may inform personalized thiopurine therapy.

These findings indicate strong associations between inherited genetic variation and ALL susceptibility in children and shed new light on ALL molecular etiology in diverse ancestry.

Recent genomic profiling of childhood acute lymphoblastic leukemia (ALL) identified a novel high-risk subtype with a gene expression signature resembling Philadelphia chromosome-positive ALL and a poor prognosis (Ph-like ALL). However, the role of inherited genetic variation in Ph-like ALL pathogenesis remains unknown. In a genome-wide association study (GWAS) of 511 ALL cases and 6,661 non-ALL controls, we identified a single susceptibility locus for Ph-like ALL (GATA3, rs3824662, P=2.17×10−14, odds ratio [OR]=3.85, for Ph-like ALL vs. non-ALL; P=1.05×10−8, OR=3.25, for Ph-like ALL vs. non-Ph-like ALL) that was independently validated. The rs3824662 risk allele was associated with somatic lesions underlying Ph-like ALL (i.e., CRLF2 rearrangement, JAK mutation, and IKZF1 deletion) and directly influenced GATA3 transcription. Finally, GATA3 SNP genotype was also associated with early treatment response and the risk of ALL relapse. Our results provide insights into interactions between host and tumor genomes and their importance in ALL pathogenesis and prognosis.

The effectiveness of antiplatelet therapy as primary prophylaxis for thrombosis in low-risk essential thrombocythemia (ET) is not proven. In this study, the incidence rates of arterial and venous thrombosis were retrospectively analyzed in 300 lowrisk patients with ET treated with antiplatelet drugs as monotherapy (n ‫؍‬ 198) or followed with careful observation (n ‫؍‬ 102).

There is increasing evidence from genome-wide association studies for a strong inherited genetic basis of susceptibility to acute lymphoblastic leukaemia (ALL) in children, yet the effects of protein-coding variants on ALL risk have not been systematically evaluated. Here we show a missense variant in CDKN2A associated with the development of ALL at genome-wide significance (rs3731249, P=9.4 × 10−23, odds ratio=2.23). Functional studies indicate that this hypomorphic variant results in reduced tumour suppressor function of p16INK4A, increases the susceptibility to leukaemic transformation of haematopoietic progenitor cells, and is preferentially retained in ALL tumour cells. Resequencing the CDKN2A–CDKN2B locus in 2,407 childhood ALL cases reveals 19 additional putative functional germline variants. These results provide direct functional evidence for the influence of inherited genetic variation on ALL risk, highlighting the important and complex roles of CDKN2A–CDKN2B tumour suppressors in leukaemogenesis.

• In this first ALL GWAS inAYAs, we determined that inherited GATA3 variants strongly influence ALL susceptibility in this age group. • These findings revealed similarities and differences in the genetic basis of ALL susceptibility between young children and AYAs.Acute lymphoblastic leukemia (ALL) in adolescents and young adults (AYA) is characterized by distinct presenting features and inferior prognosis compared with pediatric ALL. We performed a genome-wide association study (GWAS) to comprehensively identify inherited genetic variants associated with susceptibility to AYA ALL. In the discovery GWAS, we compared genotype frequency at 635 297 single nucleotide polymorphisms (SNPs) in 308 AYA ALL cases and 6,661 non-ALL controls by using a logistic regression model with genetic ancestry as a covariate. SNPs that reached P £ 5 3 10 28 in GWAS were tested in an independent cohort of 162 AYA ALL cases and 5,755 non-ALL controls. We identified a single genome-wide significant susceptibility locus in GATA3: rs3824662, odds ratio (OR), 1.77 (P 5 2.8 3 10 210 ) and rs3781093, OR, 1.73 (P 5 3.2 3 10 29 ). These findings were validated in the replication cohort. The risk allele at rs3824662 was most frequent in Philadelphia chromosome (Ph)-like ALL but also conferred susceptibility to non-Ph-like ALL in AYAs. In 1,827 non-selected ALL cases, the risk allele frequency at this SNP was positively correlated with age at diagnosis (P 5 6.29 3 10 211 ). Our results from this first GWAS of AYA ALL susceptibility point to unique biology underlying leukemogenesis and potentially distinct disease etiology by age group. (Blood. 2015;125(4):680-686)

To cite this article: Teruel R, Pé rez-Sá nchez C, Corral J, Herranz MT, Pé rez-Andreu V, Saiz E, García-Barberá N, Martínez-Martínez I, Roldá n V, Vicente V, Ló pez-Pedrera C, Martínez C. Identification of miRNAs as potential modulators of tissue factor expression in patients with systemic lupus erythematosus and antiphospholipid syndrome. J Thromb Haemost 2011; 9: 1985-92.Summary. Background: Tissue factor (TF) is the main initiator of the coagulation cascade and elements that may upregulate its expression might provoke thrombotic events. Systemic lupus erythematosus (SLE) and antiphospholipid syndrome (APS) are autoimmune diseases characterized by a high TF expression in monocytes. Objectives: To examine the role of microRNAs (miRNAs) in TF expression and to evaluate their levels in SLE and APS patients. Methods: An in silico search was performed to find potential putative binding sites of miRNAs in TF mRNA. In vitro validation was performed transfecting cells expressing TF (THP-1 and MDA-MB-231) with oligonucleotide miRNA precursors and inhibitors. Additionally, reporter assays were performed to test for the binding of miR-20a to TF mRNA. Levels of miRNAs and TF were measured by quantitative (qRT-PCR) in patients with APS and SLE. Results: Overexpression of miRNA precursors, but not inhibitors, of two of the members of cluster miR-1792, for example miR-19b and miR-20a, in cells expressing TF decreased TF mRNA, protein levels, and procoagulant activity between 30% and 60%. Reporter assays showed that miR-20a binds to TF mRNA. Finally, we measured levels of miR-19b and miR-20a in monocytes from patients with APS and SLE and observed significantly lower miRNAs levels in comparison with healthy subjects inversely correlated with the levels of TF. Conclusions: Down-regulation of miR-19b and miR-20a observed in patients with SLE and APS could contribute to increased TF expression and thus provoke the hypercoagulable state characteristic of these patients.

VKORC1 and CYP2C9 polymorphisms are used to predict the safe dose of oral anticoagulant therapy. A new variant of CYP4F2 (V433M) has recently been related to the required warfarin dose. We evaluated its influence in earliest response to acenocoumarol in 100 selected men who started anticoagulation (3 mg for 3 consecutive days). V433M genotype exerted a gene dosage-dependent effect on the decrease of factors II, VII, IX, and X in the earliest response to acenocoumarol, with homozygous 433V subjects being the most sensitive. Similarly, after the initiation of therapy, international normalized ratio also experienced a gene dosage-dependent effect (P ‫؍‬ .015), and 433V subjects needed 4 mg/week less than 433M carriers to achieve a steady anticoagulation (P ‫؍‬ .043). Multivariate linear regression analysis revealed a significant contribution of V433M polymorphism to variability of both early international normalized ratio value (R 2 ‫؍‬ 0.14) and dose requirements (R 2 ‫؍‬ 0.19). Our data underline the relevant role of CYP4F2 V433M polymorphism in the pharmacogenetics of coumarin anticoagulants. (Blood. 2009;113:4977-4979)