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Patients with unexplained low blood counts often have abnormally mutated cells that are typical of blood cancers, such as myelodysplastic syndromes (MDS) or acute myelogenous leukemia (AML). Researchers recently reported this in the journal Blood. They suggest to describe these patients as having clonal cytopenias of undetermined significance (CCUS).

Brain Kwok and colleagues performed a prospective study to examine the frequency and type of mutations encountered in 144 patients with unexplained cytopenias. 15 per cent of these patients had  idiopathic cytopenias of undetermined significance (ICUS) with some evidence of dysplasia, and 69 per cent had ICUS with no dysplasia. In total, 35 per cent of ICUS patients carried a somatic mutation or chromosomal abnormality indicative of clonal hematopoiesis.

These results were validated in a cohort of 91 lower-risk MDS and 249 ICUS cases. Mutations were found in 79 per cent with MDS, 45 per cent in ICUS with dysplasia and 17 per cent in ICUS without dysplasia. The spectrum of mutated genes was in ICUS-cases mostly similar to the spectrum in MDS. The researchers suggest to describe the patients with ICUS who have these mutation as having CCUS. Clinical and mutational features are similar in these groups and may have diagnostic utility once outcomes in CCUS patients are better understood, according to the researchers.

'We don't know to what extent patients who have low blood counts and mutations are at increased risk of developing an overt malignancy,' said Rafael Bejar, hematologist and senior author of the study. 'We hope that by defining CCUS, future studies will follow these patients to learn what these mutations mean for their future as their genetically abnormal cells may represent early stages of subsequent blood cancers.' Bejar describes the mutated cells in CCUS patients as "polyps" of the bone marrow. Just as polyps detected in colonoscopies represent growths capable of evolving into cancers, the mutated blood cells in CCUS patients may be the precursors to cancers of the blood like MDS and AML.

Sources: Blood and University of California - San Diego

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