title: Frequency of Paroxysmal Nocturnal Hemoglobinuria Clones by Multiparametric Flow Cytometry in Pediatric Aplastic Anemia Patients of Indian Ethnic Origin.
abstract: BACKGROUND
  The literature on paroxysmal nocturnal hemoglobinuria (PNH) in aplastic anemia (AA) is largely focused on adults with few studies in children. Moreover, large studies are conspicuously absent from developing countries. Knowledge of the prevalence and utility of their detection is required before widespread use of PNH screening in pediatric AA in resource-limited settings.
  
  
  METHODS
  We performed a retrospective audit over a period of 9 years to study the prevalence of PNH clones by flow cytometry (FCM) in children ≤12 years of age presenting with AA, and analyzed their response to immunosuppressant therapy.
  
  
  RESULTS
  Nine (12.9%) out of 70 patients had PNH clones comprising >1% of the target cell population, including five patients (7.14%) with PNH clone size >10%. The clone size in monocytes ranged from 3.7% to 95.2% (median 21.1%) and in neutrophils from 1.6% to 87.6% (median 19.5%). Fluorescent aerolysin (FLAER)-based FCM screening significantly improved the detection of PNH clones compared to non-FLAER based screening techniques (18.4% vs. 6.25%). One child showed chronic intravascular hemolysis and another developed arterial stroke during the course of illness. None of our PNH-positive AA patients tested for chromosome breakage studies (n = 8) showed increased clastrogen-induced breakage.
  
  
  CONCLUSIONS
  A lower frequency but moderate/large-sized PNH clones were seen in our pediatric AA population, compared to western data. FLAER-based FCM screening significantly improved the detection of PNH clones. We recommend routine FLAER-based screening of PNH in pediatric AA patients.
authors.affiliation: Department of Hematology, Postgraduate Institute of Medical Education and Research, Chandigarh, India.
authors.forename: Sreejesh
authors.initials: S
authors.lastname: Sreedharanunni
authors.affiliation: Department of Hematology, Postgraduate Institute of Medical Education and Research, Chandigarh, India.
authors.forename: Man Updesh Singh
authors.initials: MU
authors.lastname: Sachdeva
authors.affiliation: Department of Hematology, Postgraduate Institute of Medical Education and Research, Chandigarh, India.
authors.forename: Parveen
authors.initials: P
authors.lastname: Bose
authors.affiliation: Department of Hematology, Postgraduate Institute of Medical Education and Research, Chandigarh, India.
authors.forename: Neelam
authors.initials: N
authors.lastname: Varma
authors.affiliation: Hematology/Oncology Unit, Advanced Pediatric Center, Postgraduate Institute of Medical Education and Research, Chandigarh, India.
authors.forename: Deepak
authors.initials: D
authors.lastname: Bansal
authors.affiliation: Hematology/Oncology Unit, Advanced Pediatric Center, Postgraduate Institute of Medical Education and Research, Chandigarh, India.
authors.forename: Amita
authors.initials: A
authors.lastname: Trehan
mesh_terms: D000741:Anemia, Aplastic / Q000150:complications*; D002648:Child; D002675:Child, Preschool; D002999:Clone Cells; D005260:Female; D005434:Flow Cytometry; D006457:Hemoglobinuria, Paroxysmal / Q000175:diagnosis / Q000453:epidemiology*; D006801:Humans; D007194:India; D008297:Male; D015995:Prevalence; D012189:Retrospective Studies; D044465:White People / Q000235:genetics*
keywords: PNH clones; aplastic anemia; flow cytometry; pediatrics