Congenital thrombotic thrombocytopenic purpura with novel mutations ...

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Sep 30, 2013 - Congenital thrombotic thrombocytopenic purpura (TTP) is characterized by recurrent episodes of thrombocytopenia, micro- angiopathic ...
Pediatr Blood Cancer 2014;61:558–561

BRIEF REPORT Congenital Thrombotic Thrombocytopenic Purpura With Novel Mutations in Three Unrelated Turkish Children Ayse Metin,

MD, PhD,

1

* Sule Unal, MD,2 Fatma Gu¨mru¨k, MD,2 Roberta Palla, PhD,3,4 Andrea Cairo, Mary Underwood, MD,3,4,6 and Aytemiz Gurgey, MD2

Congenital thrombotic thrombocytopenic purpura (TTP) is an inherited disease caused by mutations in the ADAMTS 13 gene and has been reported to have diverse ages of presentation, ranging from the newborn period to adulthood. Herein, we present three cases of congenital TTP who were symptomatic during childhood (neonatal period, 7 and 10 years) and were each initially given different

MD,

5

diagnoses. Congenital TTP was later diagnosed by molecular analysis and responsiveness to fresh frozen plasma. Three novel mutations in a homozygous state were identified in these patients: c.1308G>C, c.428T>C (p.Ile143Thr) and c.1709A>G (p.Tyr570Cys). Pediatr Blood Cancer 2014;61:558–561. # 2013 Wiley Periodicals, Inc.

Key words: ADAMTS13 deficiency; ADAMTS13 mutation; c.1308G>C; c.428T>C; c.1709A>G mutations; thrombotic thrombocytopenic purpura; congenital TTP; Upshaw–Schulman syndrome

INTRODUCTION Congenital thrombotic thrombocytopenic purpura (TTP) is characterized by recurrent episodes of thrombocytopenia, microangiopathic hemolytic anemia (MAHA), and microvascular thrombosis and ischemic damage of multiple organs that may lead to death, end stage renal failure, or neurological sequelae in the absence of appropriate treatment [1–3]. Congenital TTP has an autosomal recessive mode of inheritance and is caused by mutations in the ADAMTS13 gene [4]. ADAMTS13 is a zinc metalloprotease present in plasma and is responsible for the cleavage of von Willebrand factor [5,6]. When there is a deficiency of ADAMTS13, uncleaved multimers circulate in plasma and cause increased platelet adhesion and aggregation, particularly in the microcirculation, resulting in the formation of thrombi [7–9]. The development of microthrombi results in MAHA and causes variable symptoms of organ ischemia and dysfunction [7]. In this manuscript, we report three Turkish patients, of whom one was symptomatic during the newborn period, whereas the other two displayed symptoms at the ages of 7 and 10 years.

CASE REPORTS

congenital TTP. By the third day of FFP infusion, hemoglobin and platelets returned to normal. The diagnosis was confirmed by the presence of undetectable ADAMTS13 activity and antigen as measured by collagen binding assay and ELISA, respectively [8]. A homozygous mutation, c.1308G>C within the ADAMTS13 gene was detected.

Case 2 A 7-year-old male presented with pneumonia and was diagnosed with tuberculosis. A detailed medical history revealed that he had easy bruising and anemia since birth. During the 9-month treatment period for tuberculosis the patient’s hemoglobin level and thrombocyte count remained low. In terms of family history, the patient’s parents were second degree cousins and the patient has an elder brother and sister. At the age of 13, physical examination during a routine followup visit revealed the presence of icteric sclera with widespread petechia and purpura. Blood work-up exhibited anemia, thrombocytopenia, fragmented erythrocytes, and schistocytes. Elevated serum LDH (1460 IU/L) was detected. A diagnosis of atypical hemolytic-uremic syndrome (HUS) was made and FFP infusion

Clinical and laboratory data of cases are summarized in Table I.

Case 1 A full term male was referred 12 hours after birth for pallor and purpuric skin lesions. Maternal obstetric history was prominent with three fetal demises, all at the eighth month of gestation. The parents were third degree cousins. Hemogram revealed anemia and thrombocytopenia. A peripheral blood (PB) smear exhibited schistocytes. Serum renal and liver function analyses revealed hyperbilirubinemia and high serum creatinine. After phototherapy, exchange transfusion, and fluid replacement, the patient improved and serum biochemistry returned to normal. He was admitted for acute bronchiolitis at 10-month-old and was found to have anemia, reticulocytosis, thrombocytopenia, and schistocytes with a serum LDH of 654 U/L (150–360). Fresh frozen plasma (FFP) infusion was given with a possible diagnosis of

1 Division of Pediatric Immunology and Allergy, Ankara Children’s Hematology Oncology Training and Research Hospital, Ministry of Health, Ankara, Turkey; 2Division of Pediatric Hematology, Hacettepe University, Ankara, Turkey; 3Dipartimento di Fisiopatologia MedicoChirurgica e dei Trapianti, Angelo Bianchi Bonomi Hemophilia and Thrombosis Center, Universita` degli Studi di Milano, Milan, Italy; 4 Luigi Villa Foundation, Milan, Italy; 5Angelo Bianchi Bonomi Hemophilia and Thrombosis Center, Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico, Milan, Italy; 6Haemostasis Research Unit, Department of Haematology, University College London, London, UK

Conflict of interest: Nothing to declare.  Correspondence to: Ayse Metin, Division of Pediatric Immunology and Allergy, Ankara Children’s Hematology Oncology Training and Research Hospital, Ministry of Health, Diskapi, Ankara, Turkey. E-mail: [email protected]

Received 17 June 2013; Accepted 13 August 2013

 C 2013 Wiley Periodicals, Inc. DOI 10.1002/pbc.24764 Published online 30 September 2013 in Wiley Online Library (wileyonlinelibrary.com).

Pediatr Blood Cancer DOI 10.1002/pbc

Age at last follow-up Outcome

ADAMTS13 activity (normal range 46–160%) Anti-ADAMTS13 autoantibodies by ELISA (positive sample >1.2%) Molecular analysis

Age at presentation/diagnosis History of intrauterine death in mother Hb (g/dl) Reticulocyte (%) Platelet count (109/L) Schistocytes Unconjugated bilirubin (mg/dl) Urea (mg/dl) Creatinine (mg/dl) Clinical presentation

Date of birth/gender Consanguinity and ethnicity

6.5 5.5 45.0

C (Exon 5), leading to p.Ile143Thr localized in the metalloprotease domain 25 years Healthy with FFP infusion

T (c.IVS11-1G>T) localized in the TSP-1 domain 12 years Healthy with FFP infusion

C mutation located in exon 5 leading to p. Ile143Thr in case 2 is localized in the metalloproteinase domain which contains the catalytic site of the enzyme [10]. It was previously reported that no residual ADAMTS13 activity could be detected in the plasma of case 2 [11]. A lower residual ADAMTS13 activity in patients has been shown to be associated with a more severe clinical phenotype [11] and so this mutation appears to have a damaging effect on the protein leading to a severe phenotype. Combining the three separate families reported here along with others that have been reported in the literature, congenital TTP has been identified in a total of six Turkish families [11,12]. Different mutations were observed in each of these six Turkish families. In the literature, apart from the 4143InsA mutation, common TTP mutations have not been described. This mutation was reported in only one of the Turkish families with TTP. This finding indicates that TTP in Turkish patients (as in other ethnic groups) is a heterogeneous entity at molecular level as reported previously [13– 17]. In conclusion, it is interesting to seldomly observe patients with congenital TTP in our country, where consanguineous marriages are common. This may be due to the fact that the disease may be misdiagnosed during childhood. Congenital TTP should be considered in adults with recurrent TTP which may help to identify undiagnosed cases.

ACKNOWLEDGMENTS DISCUSSION Although some congenital TTP cases are symptomatic at birth, the patients can be diagnosed at various ages with diverse presentations. Patients may be misdiagnosed as having ITP, idiopathic hemolytic anemia, disseminated intravascular coagulopathy, or HUS. With regards to the three patients indicated here, the diagnosis of TTP was not made during the onset of the initial symptoms but during follow-up. Although hemolytic anemia, thrombocytopenia, schistocytes, and high LDH levels were present in the first and third cases at initial presentation, a diagnosis of TTP was considered only after the patients responded to FFP. In the second case, FFP was administered to treat the coagulation disorder, which provided an improvement in thrombocytopenia and a decrease in LDH levels and hence, the patient was diagnosed with TTP. The mothers of two patients had a history of spontaneous abortion and intrauterine fetal death in earlier pregnancies. The fetal losses in the present study may be due to the development of placental thrombosis. Missense mutations were detected in all cases. The missense mutation in case 1 is situated at the end of exon 11 at the boundary between exon 11 and intron 11. Along with causing an amino acid change this mutation is predicted to affect the splicing process (http://www.fruitfly.org/seq_tools/splice.html). An alternative donor splicing splice 115 nucleotides after the mutation is predicted to be used instead. If this is the case this could lead to the production of Pediatr Blood Cancer DOI 10.1002/pbc

We thank Prof. Flora Peyvandi from Dipartimento di Fisiopatologia Medico-Chirurgica e dei Trapianti, Universita` degli Studi di Milano, A. Bianchi Bonomi Hemophilia and Thrombosis Center Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico, Milan, Italy and Luigi Villa Foundation, Milan, Italy, for assisting in management of these patients.

REFERENCES 1. George IN. Clinical practice. Thrombotic thrombocytopenic purpura. N Eng J Med 2006;354:1927– 1935. 2. Loirat C, Veyradier A, Girma JP, et al. Thrombotic thrombocytopenic purpura associated with von Willebrand factor-cleaving protease (ADAMTS13) deficiency in children. Semin Thromb Hemost 2006;32:90–97. 3. Furlan M, Robles R, Solenthaler M, et al. Deficient activity of von Willebrand factor-cleaving protease in chronic relapsing thrombotic thrombocytopenic purpura. Blood 1997;89:3097–3103. 4. Levy GG, Nichols WC, Lian EC, et al. Mutations in a member of the ADAMTS gene family cause thrombotic thrombocytopenic purpura. Nature 2001;413:488–494. 5. Zheng X, Chung D, Takayama TK, et al. Structure of von Willebrand factor cleaving protease (ADAMTS13), a metaloprotease involved in thrombotic thrombocytopenic purpura. J Biol Chem 2001;276:41059–41063. 6. Tsai HM. Physiologic cleavage of von Willebrand factor by a plasma protease is dependent on its conformation and requires calcium ion. Blood 1996;87:4235–4244. 7. Moake JL. Thrombotic microangiopathies. N Eng J Med 2002;347:589–600. 8. Peyvandi F, Lavoretano S, Palla R, et al. ADAMTS13 and anti-ADAMTS13 antibodies as markers for recurrence of acquired thrombotic thrombocytopenic purpura during remission. Haematologica 2008;93:232–239. 9. Peyvandi F, Ferrari S, Lavoretano S, et al. Von Willebrand factor cleaving protease (ADAMTS-13) and ADAMTS-13 neutralizing antibodies in 100 patients with thrombotic thrombocytopenic purpura. Br J Haematol 2004;127:433–439. 10. Zheng X, Chung D, Takayama TK, et al. Structure of von Willebrand factor-cleaving protease (ADAMTS!^), a metalloprotease involved in thrombotic thrombocytopenic purpura. J Biol Chem 2001;276:41059–41063. 11. Lotta LA, Wu HM, Mackie IJ, et al. Residual plasmatic activity of ADAMTS13 is correlated with phenotype severity in congenital thrombotic thrombocytopenic purpura. Blood 2012;120:440– 448.

Congenital TTP Cases From Turkey 12. Garagiola I, Valsecchi C, Lavoretano S, et al. Nonsense-mediated mRNA decay in the ADAMTS13 gene caused by a 29-nucleotide deletion. Heamatologica 2008;93:1678–1685. 13. Lotta LA, Garagiola I, Palla R, et al. ADAMTS13 mutations and polymorphisms in congenital thrombotic thrombocytopenic purpura. Hum Mutat 2010;31:11–19. 14. Kokame K, Matsumoto M, Soejima K, et al. Mutations and common polymorphisms in ADAMTS13 gene responsible for von Willebrand factor cleaving protease activity. Proc Natl Acad Sci USA 2002;99: 11902–11907.

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15. Plaimauer B, Fuhrmann J, Mohr G, et al. Modulation of ADAMTS13 secretion and specific activity by a combination of common amino acid polymorphisms and a missense mutation. Blood 2006;107:118–125. 16. Lotta LA, Garagiola I, Cairo A, et al. Genotype–phenotype correlation in congenital ADAMTS13 deficient patients. Blood (ASH Annu Meet Abstr) 2008;112:273. 17. Palla R, Lavoretano S, Lombardi R, et al. The first deletion mutation in the TSP1-6 repeat domain of ADAMTS13 in a family with inherited thrombotic thrombocytopenic purpura. Haematologica 2009;94:289–293.