Beyond Blood Counts: What You Should Know About Myeloproliferative Neoplasms

What are Myeloproliferative Neoplasms?

Myeloproliferative neoplasms (MPNs) are a group of diseases that happen when the bone marrow makes too many blood cells. This could mean too many red blood cells, platelets or abnormal blood cells, depending on the type of MPN.

The three major classical MPNs are:

       · Polycythemia Vera (PV) – mainly associated with an increased production of red blood cells.

       · Essential Thrombocythemia (ET) – mainly associated with an increased number of platelets.

       · Primary Myelofibrosis (PMF) – a condition in which abnormal blood-cell production is associated with changes and scarring in the bone marrow.

Another important myeloid disorder is Chronic Myeloid Leukemia (CML), which is different from these classical MPNs and is associated with a molecular change called BCR-ABL1.

Why Can MPNs Be Difficult to Identify?

Changes in blood counts are often an early sign. But abnormal blood counts alone do not always explain why these changes are happening.

This is where molecular testing can add information. It can search for specific genetic changes that are associated with different myeloid disorders and help health-care professionals better understand the underlying disease.

The Role of Molecular Testing

Certain genetic changes are commonly associated with MPNs. For example, JAK2, CALR and MPL are important markers in classical BCR-ABL1-negative MPNs while BCR-ABL1 is an important marker in CML.

Prevalence of Key Molecular Markers in MPNs

       ·  JAK2: approximately 98% in Polycythemia Vera (PV), 55% in Essential Thrombocythemia (ET) and 60% in Primary Myelofibrosis (PMF).

       ·  CALR: approximately 25–30% in ET and 20–30% in PMF; it is generally absent in PV.

       ·  MPL: approximately 5–7% in ET and 7–10% in PMF; it is rarely detected in PV.

The most frequent driver mutation identified is JAK2, especially in PV. CALR and MPL mutations are less common but clinically significant in ET and PMF. Reported frequencies may vary by study and by patient populations.

The finding of these markers may add another layer of information to the diagnostic process. However, molecular findings are not interpreted alone but together with the patient’s symptoms, blood counts, blood and bone-marrow findings and other laboratory investigations.

Why Early Identification Matters

Identifying relevant molecular markers early can be particularly useful when a person has persistent, unexplained changes in blood counts or other findings that raise suspicion of a myeloid disorder.

Molecular testing can complement conventional investigations and contribute to a clearer understanding of the disease. This information may also support disease classification and subsequent clinical management.

From Blood Counts to Better Understanding

MPNs can be complicated as many conditions can have similar blood count changes. Beyond routine blood testing and looking for relevant molecular markers can provide valuable additional information.

The TRUPCR^® MPN Panel Kit is designed for the detection of BCR-ABL1, JAK2, CALR and MPL abnormalities to assist in the assessment of patients suspected of having an MPN, including the differentiation of BCR-ABL1-associated CML in the diagnostic assessment.

High analytical sensitivity for classical MPN markers with LOD of 0.5% for JAK2 V617F, 1% for CALR and MPL variants is offered by the kit, the kit shows clinical sensitivity of 96.36% and specificity of 98.77%.

Conclusion

Understanding MPNs isn’t as simple as looking at blood-cell counts. Clinical findings, routine laboratory tests and molecular information together provide a more complete picture of the disease.

Molecular testing can aid in the evaluation and classification of suspected myeloid neoplasms and can complement conventional diagnostic approaches by identifying relevant molecular markers.

Research That Matters

1. Rahman K, Biswas S, Sharma A, Gupta K, Chandra D, Singh MK, Gupta R, Mishra A, Kumar S, Gupta A, Hasan F, Nityanand S, Kahsyap R. Prevalence and clinicopathological features of driver gene mutations profile in BCR:ABL1 negative classical myeloproliferative neoplasm-A single-center study from North India. Indian J Pathol Microbiol. 2024;67(4):739-746. https://pubmed.ncbi.nlm.nih.gov/38718214/

2. Aqbal Faiq Mohammed, Anfal Mohammed Khudhair, Dunia, Jawad Ridha. Prevalence of Factor V Leiden Mutation in Iraqi, Patients with Essential Thrombocythemia and its Association with MPN Driver Mutations: A Retrospective Cross-Sectional, Study. AIMCJ. 2026;3(2):56-70. https://aimcj.aliraqia.edu.iq/index.php/pub/article/view/310