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Genetic Variant Detection in the CALR gene using High Resolution Melting Analysis
Published on: August 26, 2020
Calreticulin Type 26 Mutation in Myelofibrosis: A Rare Variant With Diagnostic Challenges.
Teresa Maltese1, Giuseppina Raffa1, Fabio Stagno2
1Division of Advanced Diagnostic Laboratories, Department of Clinical and Experimental Medicine, University Hospital "G. Martino" Messina, Messina, Italy.
Journal of Clinical Laboratory Analysis
|May 14, 2026
Summary
Routine assays miss rare CALR mutations in myeloproliferative neoplasms (MPNs). Comprehensive sequencing is crucial for accurate diagnosis and classification of these challenging hematologic disorders.
Area of Science:
- Hematology
- Molecular Diagnostics
- Oncology
Background:
- Myeloproliferative neoplasms (MPNs) are clonal hematologic disorders often driven by JAK2, MPL, or CALR mutations.
- Standard CALR assays primarily detect common exon 9 variants (Type 1 and 2), potentially missing rare mutations.
Purpose of the Study:
- To highlight diagnostic challenges posed by rare CALR mutations in MPNs.
- To emphasize the importance of advanced molecular testing for accurate MPN diagnosis.
Main Methods:
- Case report of a 78-year-old woman with MPN initially negative for JAK2 and common CALR mutations.
- Utilized repeat hematologic evaluation, bone marrow biopsy, Sanger sequencing, cloning, and next-generation sequencing (NGS) after disease progression.
Main Results:
- A rare CALR c.1122delG frameshift mutation (Type 26) was identified by advanced testing, missed by initial assays.
- NGS confirmed heterozygosity with a 43% variant allele frequency; a CBL splice-site mutation was also detected.
- Disease progression showed thrombocytosis, leukocytosis, anemia, and primary myelofibrosis.
Conclusions:
- Routine CALR assays have limitations in detecting rare variants, impacting MPN diagnosis.
- Comprehensive sequencing approaches are essential for identifying rare CALR mutations.
- Expanded molecular testing improves diagnostic accuracy and clinical classification in MPNs.
