title: Nucleophosmin mutation analysis in acute myeloid leukaemia: Immunohistochemistry as a surrogate for molecular techniques.
abstract: OBJECTIVE
  Mutation of nucleophosmin (NPM1) gene in the absence of FLT3-ITD (FMS related tyrosine kinase 3 - internal tandem duplications) mutation carries a good prognosis in cytogenetically normal acute myeloid leukaemia (AML). NPM1, a multifunctional nucleolar phosphoprotein that shuttles between nucleus and cytoplasm, gets trapped in the cytoplasm when mutated. Immunohistochemical (IHC) demonstration of its aberrant cytoplasmic location (NPMc+) has been suggested as a simple substitute for the standard screening molecular method. This study was aimed to assess the diagnostic utility of IHC on formalin fixed bone marrow biopsies in comparison with the reference molecular method (allele specific oligonucleotide - polymerase chain reaction; ASO-PCR) to predict NPM1 mutation status in AML patients.
  
  
  METHODS
  NPM protein IHC was performed using mouse anti-NPM monoclonal antibody on 35 paraffin-embedded bone marrow biopsies of patients with primary AML of any French-American-British (FAB) subtype. Results of IHC were compared with those of ASO-PCR.
  
  
  RESULTS
  Of the 35 AML patients, 21 (60%) were positive for NPM1 exon 12 gene mutation by ASO-PCR, 19 (90.47%) of these 21 were NPMc+. Thirteen of the 35 patients were negative by both the methods. One NPMc+ patient was not detected by ASO-PCR. IHC had a sensitivity and specificity of 90 and 93 per cent, respectively, compared to the molecular screening gold standard.
  
  
  CONCLUSIONS
  Mutation of NPM1 determined by the widely available and inexpensive IHC agrees closely with results of the standard molecular methods. Thus, technically and financially not well endowed laboratories can provide the prognostically and potentially therapeutically important information on NPM1 mutation using IHC.
authors.affiliation: Department of Laboratory Oncology, Institute Rotary Cancer Hospital, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Anita
authors.initials: A
authors.lastname: Chopra
authors.affiliation: Department of Laboratory Oncology, Institute Rotary Cancer Hospital, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Sushant
authors.initials: S
authors.lastname: Soni
authors.affiliation: Department of Haematology, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Haraprasad
authors.initials: H
authors.lastname: Pati
authors.affiliation: Department of Laboratory Oncology, Institute Rotary Cancer Hospital, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Dev
authors.initials: D
authors.lastname: Kumar
authors.affiliation: Department of Laboratory Oncology, Institute Rotary Cancer Hospital, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Rahul
authors.initials: R
authors.lastname: Diwedi
authors.affiliation: Department of Laboratory Oncology, Institute Rotary Cancer Hospital, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Deepak
authors.initials: D
authors.lastname: Verma
authors.affiliation: Department of Laboratory Oncology, Institute Rotary Cancer Hospital, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Garima
authors.initials: G
authors.lastname: Vishwakama
authors.affiliation: Department of Medical Oncology, Institute Rotary Cancer Hospital, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Sameer
authors.initials: S
authors.lastname: Bakhshi
authors.affiliation: Command Hospital (Eastern Command), Kolkata, India.
authors.forename: Suman
authors.initials: S
authors.lastname: Kumar
authors.affiliation: Department of Medical Oncology, Institute Rotary Cancer Hospital, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Ajay
authors.initials: A
authors.lastname: Gogia
authors.affiliation: Department of Laboratory Oncology, Institute Rotary Cancer Hospital, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Rajive
authors.initials: R
authors.lastname: Kumar
mesh_terms: D000293:Adolescent; D000328:Adult; D000911:Antibodies, Monoclonal / Q000235:genetics; D002648:Child; D004252:DNA Mutational Analysis; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D015470:Leukemia, Myeloid, Acute / Q000235:genetics* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D009687:Nuclear Proteins / Q000235:genetics* / Q000302:isolation & purification; D000090243:Nucleophosmin
chemical_list: D000911:Antibodies, Monoclonal; C000716967:NPM1 protein, human; C000715570:Npm1 protein, mouse; D009687:Nuclear Proteins; D000090243:Nucleophosmin