The myeloproliferative diseases (MPDs) or myelo-proliferative neoplasms (MPNs) are a group of diseases of the bone marrow in which excess cells are produced. Chronic idiopathic myelofibrosis (CIMF) is a stem cell defect characterized by splenomegaly with multiorgan extramedullary hematopoiesis, immature peripheral blood granulocytes and erythrocytes and progressive bone marrow fibrosis. The most common chromosomal abnormalities seen in CIMF patients include numerical changes of chromosomes 7, 8 and 9, and structural changes of 1q, 5q, 13q and 20q. At least 75.0% of patients with bone marrow abnormalities have one or more of these chromosomal anomalies. Detection of the Janus kinase 2 (JAK2) mutation may be a potential major breakthrough for understanding the pathobiology of MPNs, and is an essential part of the diagnostic algorithm. In this study, we describe a JAK2(V617F) mutation negative CIMF patient who has the chromosomal translocation t(3;12)(q26;q21) in her karyotype.

The currently used regulatory in vitro mutagenicity/genotoxicity test battery has a high sensitivity for detecting genotoxicants, but it suffers from a large number of irrelevant positive results (i.e. low specificity) thereby imposing the need for additional follow-up by in vitro and/or in vivo genotoxicity tests. This could have a major impact on the cosmetic industry in Europe, seen the imposed animal testing and marketing bans on cosmetics and their ingredients. Afflicted, but safe substances could therefore be lost. Using the example of triclosan, a cosmetic preservative, we describe here the potential applicability of a human toxicogenomics-based in vitro assay as a potential mechanistically based follow-up test for positive in vitro genotoxicity results. Triclosan shows a positive in vitro chromosomal aberration test, but is negative during in vivo follow-up tests. Toxicogenomics analysis unequivocally shows that triclosan is identified as a compound acting through non-DNA reactive mechanisms. This proof-of-principle study illustrates the potential of genome-wide transcriptomics data in combination with in vitro experimentation as a possible weight-of-evidence follow-up approach for de-risking a positive outcome in a standard mutagenicity/genotoxicity battery. As such a substantial number of cosmetic compounds wrongly identified as genotoxicants could be saved for the future.