Clonal hematopoiesis (CH), characterized by a fraction of peripheral blood cells carrying an acquired genetic variant, emerges with age. Although in general CH is associated with increased mortality and morbidity, no higher risk of death was observed for individuals ≥80 years. Here, we investigated CH in 621 individuals aged ≥80 years from the population-based LifeLines cohort. Sensitive error-corrected sequencing of 27 driver genes at a variant allele frequency ≥1% revealed CH in the majority (62%) of individuals, independent of gender. The observed mutational spectrum was dominated by DNMT3A and TET2 variants, which frequently (29%) displayed multiple mutations per gene. In line with previous results in individuals ≥80 years, the overall presence of CH did not associate with a higher risk of death (hazard ratio, 0.91; 95% confidence interval, 0.70-1.18; P = .48). Being able to assess the causes of death, we observed no difference between individuals with or without CH, except for deaths related to hematological malignancies. Interestingly, comparison of mutational spectra confined to DNMT3A and TET2 vs spectra containing other mutated genes, showed a higher risk of death when mutations other than DNMT3A or TET2 were present (hazard ratio, 1.48; 95% confidence interval, 1.06-2.08; P = .025). Surprisingly, no association of CH with cardiovascular morbidity was found, irrespective of clone size. Further, CH associated with chronic obstructive pulmonary disease. Data on estimated exposure to DNA damaging toxicities (ie, smoking, a history of cancer [as a proxy for previous genotoxic therapy], and job-related pesticide exposure) showed an association with spliceosome and ASXL1 variants, but not with DNMT3A and TET2 variants.

Erythrocytosis is a common reason for referral to hematology services and is usually secondary in origin. The aim of this study was to assess clinical characteristics and clonal hematopoiesis (CH) in individuals with erythrocytosis in the population-based Lifelines cohort (n = 147 167). Erythrocytosis was defined using strict (World Health Organization [WHO] 2008/British Committee for Standards in Hematology) and wide (WHO 2016) criteria. Individuals with erythrocytosis (strict criteria) and concurrent leukocytosis and/or thrombocytosis were 1:2 matched with individuals with isolated erythrocytosis and analyzed for somatic mutations indicative of CH (≥5% variant allele frequency). One hundred eighty five males (0.3%) and 223 females (0.3%) met the strict criteria, whereas 4868 males (7.6%) and 309 females (0.4%) met the wide criteria. Erythrocytosis, only when defined using strict criteria, was associated with cardiovascular morbidity (odds ratio [OR], 1.8; 95% confidence interval [CI], 1.2-2.6), cardiovascular mortality (hazard ratio [HR], 2.2; 95% CI, 1.0-4.6), and all-cause mortality (HR, 1.7; 95% CI, 1.2-2.6), independent of conventional risk factors. Mutations were detected in 51 of 133 (38%) evaluable individuals, with comparable frequencies between individuals with and without concurrent cytosis. The JAK2 V617F mutation was observed in 7 of 133 (5.3%) individuals, all having concurrent cytosis. The prevalence of mutations in BCOR/BCORL1 (16%) was high, suggesting aberrant epigenetic regulation. Erythrocytosis with CH was associated with cardiovascular morbidity (OR, 9.1; 95% CI, 1.2-68.4) in a multivariable model. Our data indicate that only when defined using strict criteria erythrocytosis is associated with cardiovascular morbidity (especially in the presence of CH), cardiovascular mortality, and all-cause mortality.

Anemia is a major and currently poorly understood clinical manifestation of hematopoietic ageing. Upon ageing, hematopoietic clones harboring acquired leukemia-associated mutations expand and become detectable, now referred to as clonal hematopoiesis (CH). To investigate the relationship between CH and anemia of the elderly we explored the landscape and dynamics of CH in older anemic individuals. From the prospective population-based Lifelines cohort (n=167.729), we selected all individuals ≥60 years with anemia according to WHO criteria (n=676) and 1:1 matched controls. Peripheral blood of 1298 individuals was analyzed for acquired mutations at ≥1% variant allele frequency (VAF) in 27 driver genes. To track clonal evolution over time, we included all available follow-up samples (n=943). CH was more frequently detected in anemic individuals (46.6%) compared to controls (39.1%) (P=0.007). Although no differences were observed regarding commonly detected DTA mutations (DNMT3A, TET2, ASXL1) in anemic individuals compared to controls, other mutations were enriched in the anemia cohort, including TP53 and SF3B1. Unlike individuals with nutrient deficiency (P=0.84), individuals with anemia of chronic inflammation and unexplained anemia revealed a higher prevalence of CH (P=0.035 and P=0.017 respectively) compared to their matched controls. Follow-up analyses revealed that clones may expand and decline, generally showing only a subtle increase in VAF over 44 months (mean 0.56%), irrespective of the presence of anemia. Specific mutations associated with different growth rates and propensities to acquire an additional hit. In contrast to smaller clones (<5% VAF) which did not affect overall survival, larger clones associated with increased risk of death.