This observational, multi-center study aims to collect data to develop a novel, minimally invasive diagnostic tool for myeloproliferative neoplasms (MPN) based on peripheral blood (PB) profiling of circulating hematopoietic stem and progenitor cells (cHSPCs) using single-cell RNA sequencing (scRNA-seq). Current diagnostic practice relies on bone marrow (BM) biopsy, procedures that is invasive, technically demanding, and may be inconclusive in early or prefibrotic disease stages.

Our prior work established a reference atlas of healthy cHSPC subtypes and a computational pipeline capable of identifying disease-specific transcriptional changes by quantifying deviations from this reference. This study will assess whether PB-based genomic profiling can accurately distinguish MPN from non-clonal cytoses, including secondary erythrocytosis or thrombocytosis.

Patients referred for bone marrow biopsy due to suspected myeloproliferative neoplasm (MPN) will undergo PB collection for genomic profiling. The study's primary objective is to develop a PB-based test by comparing the developed test diagnoses to the conventional BM-based diagnostics. Secondary objectives include evaluating its potential for MPN subtype classification, risk stratification, as well as assessing its ability to reduce the need for BM biopsies.

Inclusion Criteria:

1. Age ≥ 18 years

2. Confirmed MPN diagnosis, based on the WHO criteria (Barbui 2018), which includes:

   Polycythemia Vera (PV) Criteria:

   • Elevated hemoglobin (>16.5 g/dL for men, >16.0 g/dL for women), hematocrit (>49% for men, >48% for women), or increased red cell mass
   • Bone marrow biopsy showing hypercellularity with trilineage growth (panmyelosis)
   • Presence of JAK2 mutation (V617F or exon 12)

   Essential Thrombocythemia (ET) Criteria:

   • Platelet count ≥450 ×10⁹/L
   • Bone marrow biopsy showing proliferation mainly of the megakaryocyte lineage
   • Not meeting WHO criteria (Alaggio et al., 2022) for other myeloid neoplasms (such as CML, PV, PMF, MDS).
   • Presence of JAK2, CALR, or MPL mutation Primary Myelofibrosis (PMF) Criteria
   • Megakaryocytic proliferation and atypia, with or without reticulin fibrosis, and increased marrow cellularity (for prefibrotic/early PMF) or significant reticulin/collagen fibrosis (for overt PMF)
   • Not meeting criteria for other myeloid neoplasms
   • Presence of JAK2, CALR, or MPL mutation, or in their absence, another clonal marker

3. Patients who are referred for a bone marrow biopsy due to a suspected diagnosis of MPN

Exclusion Criteria:

1. Patients diagnosed with MPN receiving therapy
2. Patients who have undergone a bone marrow transplant

Patients with MPN, or suspicion for MPN, who are referred to BM will be recruited to the study

We will send PERIBLOOD report including the genetic data, for each patients, to the participating sites