Abnormal Platelet Counts and Clonal Hematopoiesis in the General Population

Area of Science:

• Hematology
• Genetics
• Oncology

Background:

• Clonal hematopoiesis (CH) involves somatic mutations leading to hematopoietic cell expansion.
• Platelet count abnormalities, including thrombocytopenia and thrombocytosis, are common in older adults.
• The interplay between CH, platelet counts, and clinical outcomes requires further investigation.

Purpose of the Study:

• To investigate the association between platelet count abnormalities (thrombocytopenia and thrombocytosis) and CH.
• To evaluate the impact of CH and platelet abnormalities on overall survival.
• To assess the risk of developing hematological malignancies in individuals with CH and platelet count abnormalities.

Main Methods:

• Retrospective analysis of individuals aged ≥60 years from the population-based Lifelines cohort (n = 167,729).
• Case-control study comparing individuals with thrombocytopenia (n=631) or thrombocytosis (n=178) against age- and sex-matched controls.
• Analysis of CH prevalence, specific gene mutations (e.g., SF3B1, TP53, JAK2, CALR), overall survival, and incidence of hematological malignancies.

Main Results:

• CH prevalence was similar in thrombocytopenia cases and controls but higher in thrombocytosis cases.
• Spliceosome gene mutations were enriched in thrombocytopenia cases; TP53 and spliceosome mutations increased mortality risk.
• CH in thrombocytosis was associated with a 23% incidence of hematological malignancies, predominantly myeloproliferative diseases with driver mutations (JAK2, CALR, MPL).

Conclusions:

• Thrombocytopenia with CH does not affect survival, but specific mutations (TP53, spliceosome) significantly increase mortality risk.
• CH in individuals with thrombocytosis is linked to a substantial risk of developing hematological malignancies, particularly myeloproliferative neoplasms.
• These findings highlight distinct clinical implications of CH in the context of different platelet count abnormalities.