Clinical validation of a multipurpose assay for detection and genotyping of CALR mutations in myeloproliferative neoplasms.
OBJECTIVE
To develop a polymerase chain reaction (PCR)-based approach to detect CALR mutations in myeloproliferative neoplasms (MPNs) in a clinical laboratory.


METHODS
DNA was extracted from bone marrow aspirate samples of 67 JAK2 wild-type MPNs (22 with matched peripheral blood), 54 cases of unclassifiable myelodysplastic syndrome/MPN, and 16 cases of atypical chronic myeloid leukemia. We used genomic DNA to detect somatic mutations in exon 9 of CALR and PCR with fluorescently labeled and M13-tagged primers and subjected the products to capillary electrophoresis (CE) followed by Sanger sequencing. Detailed assay performance characteristics were established.


RESULTS
We identified CALR mutations in 19 (28.4%) of 67 JAK2-negative MPNs, including 14 type I (52-base pair [bp] deletion), four type II (5-bp insertions), and one type III (18-bp deletion). All mutations were confirmed by Sanger sequencing. Sensitivity studies showed 2.5% and 5% mutation detection levels by CE and Sanger sequencing, respectively, with high reproducibility.


CONCLUSIONS
This assay allows for rapid, convenient screening for CALR mutations in MPNs, thereby reducing the number of cases that require assessment by Sanger sequencing, reducing labor and improving turnaround time.
From the Departments of Hematopathology and.
Meenakshi
M
Mehrotra
From the Departments of Hematopathology and.
Rajyalakshmi
R
Luthra
From the Departments of Hematopathology and.
Rajesh R
RR
Singh
From the Departments of Hematopathology and.
Bedia A
BA
Barkoh
From the Departments of Hematopathology and.
John
J
Galbincea
From the Departments of Hematopathology and.
Pramod
P
Mehta
From the Departments of Hematopathology and.
Rashmi S
RS
Goswami
From the Departments of Hematopathology and.
Kausar J
KJ
Jabbar
From the Departments of Hematopathology and.
Sanam
S
Loghavi
From the Departments of Hematopathology and.
L Jeffrey
LJ
Medeiros
Leukemia, The University of Texas MD Anderson Cancer Center, Houston.
Srdan
S
Verstovsek
From the Departments of Hematopathology and kppatel@mdanderson.org.
Keyur P
KP
Patel
D019046:Bone Marrow Neoplasms / Q000175:diagnosis* / Q000235:genetics; D037282:Calreticulin / Q000235:genetics; D045744:Cell Line, Tumor; D004252:DNA Mutational Analysis / Q000379:methods*; D005838:Genotype; D006801:Humans; D053614:Janus Kinase 2 / Q000235:genetics; D009154:Mutation; D009196:Myeloproliferative Disorders / Q000175:diagnosis* / Q000235:genetics; D015203:Reproducibility of Results
D037282:Calreticulin; C507924:JAK2 protein, human; D053614:Janus Kinase 2
Calreticulin (CALR); Capillary electrophoresis; JAK2; Myeloproliferative neoplasms; PCR; Sanger sequencing