Papers by Toshiyuki Miyata
Haematologica, Feb 21, 2019
C ongenital thrombotic thrombocytopenic purpura is an autosomal recessive inherited disease with ... more C ongenital thrombotic thrombocytopenic purpura is an autosomal recessive inherited disease with a clinically heterogeneous course and an incompletely understood genotype-phenotype correlation. In 2006, the Hereditary TTP Registry started recruitment for a study which aimed to improve the understanding of this ultra-rare disease. The objective of this study is to present characteristics of the cohort until the end of 2017 and to explore the relationship between overt disease onset and ADAMTS13 activity with emphasis on the recurring ADAMTS13 c.4143_4144dupA mutation. Diagnosis of congenital thrombotic thrombocytopenic purpura was confirmed by severely deficient ADAMTS13 activity (≤10% of normal) in the absence of a functional inhibitor and the presence of ADAMTS13 mutations on both alleles. By the end of 2017, 123 confirmed patients had been enrolled from Europe (n=55), Asia (n=52, 90% from Japan), the Americas (n=14), and Africa (n=2). First recognized disease manifestation occurred from around birth up to the age of 70 years. Of the 98 different ADAMTS13 mutations detected, c.4143_4144dupA (exon 29; p.Glu1382Argfs*6) was the most frequent mutation, present on 60 of 246 alleles. We found a larger proportion of compound heterozygous than homozygous carriers of ADAMTS13 c.4143_4144dupA with overt disease onset at < 3 months of age (50% vs. 37%), despite the fact that ADAMTS13 activity was <1% in 18 of 20 homozygous, but in only 8 of 14 compound heterozygous carriers. An evaluation of overt disease onset in all patients with an available sensitive ADAMTS13 activity assay (n=97) shows that residual ADAMTS13 activity is not the only determinant of age at first disease manifestation. Registered at clinicaltrials.gov identifier NCT01257269.
Clinical and Applied Thrombosis-Hemostasis, Apr 25, 2018
The gain-of-function variation p.I1157T in C3 was previously identified in 8 patients with atypic... more The gain-of-function variation p.I1157T in C3 was previously identified in 8 patients with atypical hemolytic uremic syndrome (aHUS) at Mie University Hospital. In the present study, we identified another 11 patients with aHUS with this variation, including 10 pediatric patients (onset age: 1-16 years). The variation seems to be geographically concentrated around Mie Prefecture in Japan. Fifteen of the 19 patients with aHUS experienced infection as probable triggering events. All 19 patients had renal dysfunction. Seven patients, including 2 from the previous study and 5 from the present study, were treated with eculizumab, with all showing a good response with hematological normalization. Among the 5 eculizumab-treated patients in the present study, 3 had an ambiguous diagnosis of aHUS due to low-grade hemolysis even with elevated levels of lactate dehydrogenase and bilirubin. In those cases, in-house targeted DNA sequencing identified the C3 p.I1157T variation carriers, which enabled the early initiation of treatment with eculizumab. The present study supports the early introduction of eculizumab in patients with aHUS, especially pediatric patients.
Genes, Sep 28, 2021
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Genes, 2021
The genotypes of vitamin K epoxide reductase complex 1 (VKORC1) and cytochrome P450 2C9 (CYP2C9) ... more The genotypes of vitamin K epoxide reductase complex 1 (VKORC1) and cytochrome P450 2C9 (CYP2C9) can influence therapeutic warfarin doses. Conversely, nongenetic factors, especially renal function, are associated with warfarin maintenance doses; however, the optimal algorithm for considering genes and renal dysfunction has not been established. This single-center prospective cohort study aimed to evaluate the factors affecting warfarin maintenance doses and develop pharmacogenetics-guided algorithms, including the factors of renal impairment and others. To commence, 176 outpatients who were prescribed warfarin for thromboembolic stroke prophylaxis in the stroke center, were enrolled. Patient characteristics, blood test results, dietary vitamin K intake, and CYP2C9 and VKORC1 (-1639G>A) genotypes were recorded. CYP2C9 and VKORC1 (-1639G>A) genotyping revealed that 80% of the patients had CYP2C9 *1/*1 and VKORC1 mutant AA genotypes. Multiple linear regression analysis demonstrat...
Japanese Journal of Thrombosis and Hemostasis, 2020
Thrombosis journal, 2016
In recent years, genetic analyses of congenital deficiencies of three anticoagulant proteins, ant... more In recent years, genetic analyses of congenital deficiencies of three anticoagulant proteins, antithrombin, protein C (PC) and protein S (PS), in East Asian patients with venous thromboembolism (VTE) have greatly increased. The PS-K196E mutation is often identified in the Japanese population with an allelic frequency of 0.86 %, and a total of approximately 10,000 Japanese are estimated to be homozygotes. The heterozygotes show PS anticoagulant activities ranging from 40 to 110 %, and 16 % lower mean anticoagulant activity than that in wild-type individuals. Specific assay methods to identify carriers of this mutation have recently been developed. The mutation carriers are at risk of thrombosis during pregnancy but do not appear to be at risk for adverse pregnancy outcomes. To promote future research into this mutation and its relation to thrombosis, a thrombosis-prone mouse strain with the PS K196E mutation has been developed. We found the PS-K196E mutation and the heterozygous PS-d...
International journal of hematology, 2016
The congenital form of thrombotic thrombocytopenic purpura (TTP) is caused by genetic mutations i... more The congenital form of thrombotic thrombocytopenic purpura (TTP) is caused by genetic mutations in ADAMTS13. Some, but not all, congenital TTP patients manifest renal insufficiency in addition to microangiopathic hemolysis and thrombocytopenia. We included 32 congenital TTP patients in the present study, which was designed to assess whether congenital TTP patients with renal insufficiency have predisposing mutations in complement regulatory genes, as found in many patients with atypical hemolytic uremic syndrome (aHUS). In 13 patients with severe renal insufficiency, six candidate complement or complement regulatory genes were sequenced and 11 missense mutations were identified. One of these missense mutations, C3:p.K155Q mutation, is a rare mutation located in the macroglobulin-like 2 domain of C3, where other mutations predisposing for aHUS cluster. Several of the common missense mutations identified in our study have been reported to increase disease-risk for aHUS, but were not m...
PloS one, 2015
Protein S (PS) acts as a cofactor for activated protein C in the plasma anticoagulant system. PS ... more Protein S (PS) acts as a cofactor for activated protein C in the plasma anticoagulant system. PS Lys196-to-Glu (K196E) mutation is a genetic risk factor for venous thromboembolism in Japanese individuals. Because of the substantial overlap in PS anticoagulant activity between KK (wild-type) and KE (heterozygous) genotypes, it is difficult to identify PS K196E carriers by measuring PS activity. Here, we generated monoclonal antibodies specific to the PS K196E mutant and developed a simple and reliable method for the identification of PS K196E carriers. We immunized mice with a keyhole limpet hemocyanin-conjugated synthetic peptide with Glu196. The hybridoma cells were screened for the binding ability of the produced antibodies to recombinant mutant EGF-like domains of PS (Ile117-Glu283). We obtained three hybridoma cell lines producing PS K196E mutation-specific antibodies. We established a sandwich enzyme-linked immunosorbent assay (ELISA) system in which the PS K196E mutation-speci...
Journal of human genetics, 2002
Single-nucleotide polymorphisms (SNPs) located in coding regions (coding SNPs; cSNPs) with amino ... more Single-nucleotide polymorphisms (SNPs) located in coding regions (coding SNPs; cSNPs) with amino acid substitution can potentially alter protein function. Therefore, identification of the nonsynonymous cSNPs of the genes of common diseases is valuable in tests of association with phenotypes. In this study, we validated 525 candidate cSNPs from 179 hypertension candidate genes deposited in the publicly available database dbSNP by DNA sequencing of samples from 32 Japanese individuals. We identified a total of 143 SNPs (27%) in 93 hypertension candidate genes. We also identified 16 new SNPs, for a total of 159 SNPs. Of the 159 SNPs thus identified, 104 were nonsynonymous. We estimate that approximately 20% of the SNPs deposited in dbSNP database showed a minor allele frequency of over 5%. The candidate SNPs for hypertension identified in this study would be valuable for association studies with hypertension to accelerate the identification of hypertension genes.
Hämostaseologie, 2013
SummaryThrombotic thrombocytopenic purpura (TTP), a life threatening disease, can be induced by c... more SummaryThrombotic thrombocytopenic purpura (TTP), a life threatening disease, can be induced by congenital or acquired deficiency of plasma metalloprotease ADAMTS13. Since the publication of the first genetic analysis in patients with congenital ADAMTS13 deficiency in 2001, more than 100 genetic defects in the ADAMTS13 gene have been reported worldwide. Genetic analysis in patients with ADAMTS13 deficiency has greatly contributed to the understanding of the etiology of TTP. A rapid and quantitative assay method for the plasma ADAMTS13 activity was developed recently in 2005 and opened a new area of TTP research – namely genetic research using a general population to evaluate age and gender differences of ADAMTS13 activity as well as phenotype – genotype correlations of genetic polymorphisms and estimation of a homozygote or a compound heterozygote ADAMTS13 deficiencies. The Japanese general population study included 3616 individuals with an age between 30 – 80 years confirming other...
Case reports in nephrology, 2014
Atypical hemolytic uremic syndrome (aHUS) can be distinguished from typical or Shiga-like toxin-i... more Atypical hemolytic uremic syndrome (aHUS) can be distinguished from typical or Shiga-like toxin-induced HUS. The clinical outcome is unfavorable; up to 50% of affected patients progress to end-stage renal failure and 25% die during the acute phase. Multiple conditions have been associated with aHUS, including infections, drugs, autoimmune conditions, transplantation, pregnancy, and metabolic conditions. aHUS in the nontransplant postsurgical period, however, is rare. An 8-month-old boy underwent surgical repair of tetralogy of Fallot. Neurological disturbances, acute renal failure, thrombocytopenia, and microangiopathic hemolytic anemia developed 25 days later, and aHUS was diagnosed. Further evaluation revealed that his complement factor H (CFH) level was normal and that anti-FH antibodies were not detected in his plasma. Sequencing of his CFH, complement factor I, membrane cofactor protein, complement factor B, and thrombomodulin genes was normal. His ADAMTS-13 (a disintegrin-like...
Hematology / the Education Program of the American Society of Hematology. American Society of Hematology. Education Program, 2004
Thrombotic thrombocytopenic purpura (TTP) is characterized by microangiopathic hemolytic anemia a... more Thrombotic thrombocytopenic purpura (TTP) is characterized by microangiopathic hemolytic anemia and thrombocytopenia, accompanied by microvascular thrombosis that causes variable degrees of tissue ischemia and infarction. Intravascular coagulation is not a prominent feature of the disorder. Plasma exchange can induce remissions in approximately 80% of patients with idiopathic TTP, but patients have a much worse prognosis when thrombotic microangiopathy is associated with cancer, certain drugs, infections, or tissue transplantation. Recently, acquired autoimmune deficiency of a plasma metalloprotease named ADAMTS13 was shown to cause many cases of idiopathic TTP. This review describes our current understanding of how to use this knowledge clinically. In Section I, Dr. Joel Moake describes the presentation of thrombotic microangiopathy, emphasizing the pathophysiology of idiopathic TTP. Platelets adhere to ultra-large (or "unusually large") von Willebrand factor (ULVWF) mult...
Proceedings of the National Academy of Sciences, 2009
ADAMTS13 specifically cleaves plasma von Willebrand factor (VWF) and thereby controls VWF-mediate... more ADAMTS13 specifically cleaves plasma von Willebrand factor (VWF) and thereby controls VWF-mediated platelet thrombus formation. Severe deficiencies in ADAMTS13 can cause life-threatening thrombotic thrombocytopenic purpura. Here, we determined 2 crystal structures of ADAMTS13-DTCS (residues 287–685), an exosite-containing human ADAMTS13 fragment, at 2.6-Å and 2.8-Å resolution. The structures revealed folding similarities between the disintegrin-like (D) domain and the N-terminal portion of the cysteine-rich domain (designated the C A domain). The spacer (S) domain forms a globular functional unit with a 10-stranded β-sandwich fold that has multiple interaction sites with the C A domain. We expressed 25 structure-based mutants of ADAMTS13-MDTCS (residues 75–685) and measured their enzymatic activity. We identified 3 VWF-binding exosites on the linearly aligned discontinuous surfaces of the D, C A , and S domains traversing the W-shaped molecule. Since the MDTCS domains are conserved ...
Proceedings of the National Academy of Sciences, 2002
von Willebrand factor (VWF) is synthesized primarily in vascular endothelial cells and secreted i... more von Willebrand factor (VWF) is synthesized primarily in vascular endothelial cells and secreted into the plasma as unusually large VWF multimers. Normally, these multimers are quickly degraded into smaller forms by a plasma metalloproteinase, VWF-cleaving protease (VWF-CP). Decreases in the activity of this enzyme result in congenital and acquired thrombotic thrombocytopenic purpura (TTP). The human VWF-CP has recently been purified. Cloning of the corresponding cDNA revealed that the 1,427-aa polypeptide is a member of the ADAMTS gene family, termed ADAMTS13 . Twelve rare mutations in this gene have been identified in patients with congenital TTP. Here, we report missense and nonsense mutations in two Japanese families with Upshaw–Schulman syndrome, congenital TTP with neonatal onset and frequent relapses. The comparison of individual ADAMTS13 genotypes and plasma VWF-CP activities indicated that the R268P, Q449stop, and C508Y mutations abrogated activity of the enzyme, whereas the...
Nephrology Dialysis Transplantation, 2006
Background. Unlike acquired thrombotic thrombocytopenic purpura or haemolytic uraemic syndrome, w... more Background. Unlike acquired thrombotic thrombocytopenic purpura or haemolytic uraemic syndrome, which are often intractable, thrombotic microangiopathy in patients with Upshaw-Schulman syndrome (USS)-a congenital deficiency of von Willebrand factor-cleaving protease (ADAMTS13) activityresponds very well to plasma infusion and does not even require plasma exchange. However, the symptoms significantly vary in each individual and thus clinicians often overlook this diagnosis. Methods. A 31-year-old adult male patient with thrombotic microangiopathy, which was complicated with repeated episodes of acute renal failure, is reported. We suspected that the patient had USS and performed assays of ADAMT13 activity and its inhibitor, followed by ADAMTS13 gene analysis of the patient and his parents. Results. The patient had extremely low ADAMTS13 activity and has no inhibitors of ADAMTS13. Through an ADAMTS13 gene analysis of this family, we found two novel mutations responsible for the disease: a missense mutation in exon 7 [702 C ! A (H234Q)] from the father and a nonsense mutation in exon 26 [3616 C ! T (R1206X)] from the mother. Conclusions. Our experience appears to indicate the importance of assays of ADAMTS13 activity and its inhibitor in patients who have episodes of renal insufficiency in association with thrombotic microangiopathy, for diagnosis and choice of treatment.
Journal of Thrombosis and Haemostasis, 2011
Upshaw-Schulman syndrome (USS) is an extremely rare hereditary deficiency of ADAMTS13 activity, t... more Upshaw-Schulman syndrome (USS) is an extremely rare hereditary deficiency of ADAMTS13 activity, termed congenital TTP. The clinical signs are usually mild during childhood, often the isolated thrombocytopenia. But their symptoms become evident when the patients have infections or get pregnant. We identified 43 USS-patients in Japan, who ranged in age from early childhood to 79 years old. Analyzing the natural history of these USS patients based on ADAMTS13 gene mutations may characterize their clinical phenotypes. Severe neonatal jaundice that requires exchange blood transfusion, a hallmark of USS, was found in 18 of 43 patients (42%). During childhood, 25 of 43 patients were correctly diagnosed of USS without gender disparity. These 25 patients were categorized as having "the early-onset phenotype". Between 15 and 45 years of age, 15 were correctly diagnosed, and interestingly they were all female. The remaining three patients were all male and were diagnosed when they got older than 45 years of age, suggesting that they were "the late-onset phenotype". Two of these 3 males developed sudden overt TTP when they were 55 and 63 years old. These two men had two different homozygous ADAMTS13 gene mutations, p.R193W/p.R193W and p.C1024R/p.C1024R, respectively. Both of which were not discovered in the US and Western countries. In vitro expression studies showed that these two proteins were consistently secreted into the culture medium but to a lesser extent and with reduced activity compared to the wild-type protein. Our results indicate that "the late-onset phenotype" of USS is formed with ethnic specificity.
Journal of Human Genetics, 2004
To investigate the effects of polymorphisms in the ATP-binding cassette transporter A1 (ABCA1) ge... more To investigate the effects of polymorphisms in the ATP-binding cassette transporter A1 (ABCA1) gene on the high-density lipoprotein cholesterol (HDL-C) level and the incidence of myocardial infarction (MI), we performed association studies. Sequence analysis identified 14 polymorphisms in the promoter region of ABCA1. After considering linkage disequilibrium, three polymorphisms in the promoter region and 11 polymorphisms from the JSNP database were determined in 1,880 subjects recruited from the Suita Study, representing the general population in Japan. We evaluated the association between the ABCA1 genotype and HDL-C level adjusted not only for standard factors, but also for genetic factors including ApoA1 and ApoE genotypes. Of the 14 polymorphisms tested, the G()273)C (P=0.0074), C()297)T (P=0.0195), and IMS-JST071749(P=0.0093) polymorphisms were significantly associated with the HDL-C level in the Suita population. We could reconfirm that the G()273)C genotype was influential in another set of subjects (P=0.0310, n=743). However, the distribution of the ABCA1 G()273)C genotype in subjects with MI (n=598) was not different from that in the control population (n=801). These results indicate that ABCA1 G()273)C has a significant effect on the HDL-C level in the general Japanese population, but not on the incidence of MI.
Journal of Biological Chemistry, 2000
Herp is a 54-kDa membrane protein in the endoplasmic reticulum (ER). The mRNA expression level of... more Herp is a 54-kDa membrane protein in the endoplasmic reticulum (ER). The mRNA expression level of Herp is increased by the accumulation of unfolded proteins in the ER. Transcriptional changes designed to deal with this type of ER stress is called the unfolded protein response (UPR). Most mammalian UPR-target genes encode ER-resident molecular chaperones: GRP78, GRP94, and calreticulin. The promoter regions of these genes contain a cis-acting ER stress response element, ERSE, with the consensus sequence of CCAAT-N 9-CCACG. Under conditions of ER stress, p50ATF6 (the active form of the transcription factor, ATF6) binds to CCACG when CCAAT is bound by the general transcription factor, NF-Y/CBF. Here, we report the genomic structure of human Herp and the presence of a new ER stress response element, ERSE-II, in its promoter region. The gene for Herp consists of eight exons, localized to chromosome 16q12.2-13. The promoter region contains a single ERSE-like sequence. In reporter gene assays, disruption of this cis-element resulted in a partial reduction of the transcriptional response to ER stress, suggesting that the element is functional for the UPR. These results also suggest the involvement of additional elements in the UPR. Further analysis, using an optimized plasmid containing an mRNA-destabilizing sequence, revealed ERSE-II (ATTGG-N-CCACG) as the second ER stress response element. Interestingly, ERSE-II was also dependent on p50ATF6, in a manner similar to that of ERSE, despite the disparate structure. The strong induction of Herp mRNA by ER stress would be achieved by the cooperation of ERSE and ERSE-II.
Journal of Biological Chemistry, 2004
Human ADAMTS13 was recently identified as a gene encoding von Willebrand factor-cleaving protease... more Human ADAMTS13 was recently identified as a gene encoding von Willebrand factor-cleaving protease, hADAMTS13. Both congenital and acquired defects in this enzyme can cause thrombotic thrombocytopenic purpura. hADAMTS13 consists of 1,427 amino acid residues and is composed of multiple structural domains including thrombospondin type 1 motifs and CUB domains. To analyze the functional roles of these domains in vivo, we determined the cDNA sequence of the mouse ortholog, mADAMTS13. Unexpectedly, two forms of the mouse Adamts13 gene were isolated that differed in the insertion of an intracisternal A particle (IAP) retrotransposon including a premature stop codon. The IAP insertion was found in BALB/c, C3H/He, C57BL/6, and DBA/2 strains but not in the 129/Sv strain. The outbred ICR strain had either the IAP-free or IAP-inserted allele or both. IAP-free Adamts13 encoded mADAMTS13L, a protein of 1,426 amino acid residues with the same domain organization as hADAMTS13. In contrast, IAPinserted Adamts13 encoded a C-terminally truncated enzyme, mADAMTS13S, that is comprised of only 1,037 amino acid residues and lacking the C-terminal two thrombospondin type 1 motifs and two CUB domains. Strain specificity was also confirmed by reverse transcription-PCR and Northern blot analyses. Both recombinant mADAMTS13L and mADAMTS13S exhibited von Willebrand factor cleaving activities in vitro. The natural variation in mouse ADAMTS13 should allow for the determination of hitherto unknown functions of its C-terminal domains in vivo.
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Papers by Toshiyuki Miyata