Karyotyping, genotyping, and immunophenotyping
“There is no disease-defining karyotype abnormality [in CMML],” Dr. Durakovic said.
She said 30% of patients have abnormal karyotype, and the most common abnormality is trisomy 8. Unlike in patients with MDS, del(5q) and monosomal karyotypes are infrequent in patients with CMML.
Similarly, there are no “disease-defining” mutations or genetic changes in CMML, although CMML is genetically distinct from MDS, Dr. Durakovic said.
For instance, SRSF2 encodes a component of the spliceosome that is mutated in almost half of CMML patients and less than 10% of MDS patients. Likewise, ASLX1 and TET2 are “much more frequently involved” in CMML than in MDS, Dr. Durakovic said.
In a 2012 study of 275 CMML patients, researchers found that 93% of patients had at least one somatic mutation in nine recurrently mutated genes – SRFS2, ASXL1, CBL, EZH2, JAK2V617F, KRAS, NRAS, RUNX1, and TET2 ().
However, Dr. Durakovic noted that these mutations are found in other disorders as well, so this information may not be helpful in differentiating CMML from other disorders.
A 2015 study revealed a technique that does appear useful for identifying CMML – monocyte subset distribution analysis. For this analysis, monocytes are divided into the following categories:
- Classical/MO1 (CD14bright/CD16−).
- Intermediate/MO2 (CD14bright/CD16+).
- Nonclassical/MO3 (CD14dim/CD16+).
The researchers found that CMML patients had an increase in the fraction of classical monocytes (with a cutoff value of 94%), as compared to healthy control subjects, patients with another hematologic disorder, and patients with reactive monocytosis ().
A 2018 study confirmed that monocyte subset distribution analysis could differentiate CMML from other hematologic disorders, with the exception of atypical CML. This study also suggested that a decreased percentage of non-classical monocytes was more sensitive than an increased percentage of classical monocytes ().
Despite the differences between these studies, “monocyte subset distribution analysis is showing promise as a method of identifying hard-to-identify CMML patients with ease and affordability,” Dr. Durakovic said.
She added that the technique can be implemented in clinical practice using the.
Dr. Durakovic did not report any conflicts of interest.
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