title: Severe thrombocytopenia in a patient with inosine triphosphatase (ITPA)-CC genotype caused by pegylated interferon (IFN)-α-2a with ribavirin therapy: a case report.
abstract: BACKGROUND
  Pegylated interferon combined with ribavirin treatment is an effective therapy for chronic hepatitis C viral infection. However, pegylated interferon combined with ribavirin is associated with various adverse reactions. Severe thrombocytopenia is a life-threatening side effect of interferon therapy that can lead to bleeding. It is generally understood that the inosine triphosphatase-CC genotype does not have a significantly lower reduction by pegylated interferon combined with ribavirin in the mean platelet counts compared with the AA/CA genotype. We report a case of severe thrombocytopenia that developed in a patient with chronic hepatitis C treated with pegylated interferon combined with ribavirin in spite of having the inosine triphosphatase-CC genotype.
  
  
  METHODS
  A 57-year-old female had been diagnosed as having HCV infection in 2008. The inosine triphosphatase gene showed one single nucleotide polymorphism (rs1127354) C/C (major homozygous) and the IL28B gene showed single nucleotide polymorphism (rs8099917 T/T, rs11881222 T/T) (major homozygous). The patient was treated with pegylated interferon 180 μg once a week combined with ribavirin 600 mg per day from April 2011. The hepatitis c virus ribonucleic acid turned negative 9 weeks after treatment with pegylated interferon combined with ribavirin. During the therapy, the platelet count remained above 8.0 × 10(4)/μl for about 9 months. In January 2012, the platelet count was 6.8 × 10(4)/μl. In February 2012, the 44th week from the beginning of the treatment, a sudden decrease in the platelet count to 0.8 × 10(4)/μl was observed. After prednisolone was administered, the platelet count increased. Finally the platelet count had risen above normal range.
  
  
  CONCLUSIONS
  We should pay careful attention in the differential diagnosis for patients with the inosine triphosphatase-CC genotype because, although rare, severe thrombocytopenia could occur.
authors.forename: Weimin
authors.initials: W
authors.lastname: Jiang
authors.affiliation: Department of Gastroenterology, Kitasato University School of Medicine, East Hospital, 2-1-1 Asamizodai, Minami-ku, Sagamihara, Kanagawa 252-0380, Japan. hisashi7@kitasato-u.ac.jp.
authors.forename: Hisashi
authors.initials: H
authors.lastname: Hidaka
authors.forename: Takahide
authors.initials: T
authors.lastname: Nakazawa
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Kitagawa
authors.forename: Wasaburo
authors.initials: W
authors.lastname: Koizumi
mesh_terms: D000998:Antiviral Agents / Q000009:adverse effects; D004359:Drug Therapy, Combination; D005260:Female; D005838:Genotype; D005938:Glucocorticoids / Q000627:therapeutic use; D019698:Hepatitis C, Chronic / Q000188:drug therapy; D006801:Humans; D016898:Interferon-alpha / Q000009:adverse effects*; D008875:Middle Aged; D010976:Platelet Count; D011092:Polyethylene Glycols / Q000009:adverse effects*; D011239:Prednisolone / Q000627:therapeutic use; D011755:Pyrophosphatases / Q000235:genetics*; D011994:Recombinant Proteins / Q000009:adverse effects; D012254:Ribavirin / Q000009:adverse effects*; D013921:Thrombocytopenia / Q000139:chemically induced* / Q000188:drug therapy; D016896:Treatment Outcome; D000097630:Inosine Triphosphatase
chemical_list: D000998:Antiviral Agents; D005938:Glucocorticoids; D016898:Interferon-alpha; D011092:Polyethylene Glycols; D011239:Prednisolone; D011755:Pyrophosphatases; D011994:Recombinant Proteins; D012254:Ribavirin; D000097630:Inosine Triphosphatase; C100416:peginterferon alfa-2a