The primary pathology in many cases of myelodysplasia (MDS) and acute myeloid leukemia (AML) remains unknown. In some cases, two or more affected members have been identified in the same family. To date, mutations in two genes have been directly implicated: the hematopoietic transcription factors RUNX1 (runt-related transcription factor 1) and CEBPA (CCATT-box enhancer binding protein alpha). However, there are also other familial cases of MDS/AML where the genetic basis remains unknown. Both MDS, and to a lesser extent AML, have been observed in cases of the bone marrow failure syndrome dyskeratosis congenita, in which telomerase mutations have been identified. Recently, an increased incidence of telomerase reverse transcriptase mutations has been reported in a series of de novo AML. We have now identified novel mutations in the telomerase RNA (TERC) or telomerase reverse transcriptase component (TERT) within 4 of 20 families presenting with familial MDS/AML. Functional analysis has demonstrated that all mutations adversely impact on telomerase activity in vitro, and affected individuals have short telomeres. These families, in conjunction with a review of previously published cases, help to further define the pathological role of telomerase mutations in MDS/AML and have implications for the biology, treatment and screening regimen of de novo cases.

Within the contemporary multitude of complex methods used in clinical flow cytometry, very few techniques exist which can be described as disease-specific diagnostic tests. Detection of glycophosphatidylinositol (GPI)-linked antigens on hematopoietic cells using monoclonal antibodies and flow cytometry forms the basis of a specific diagnostic test for paroxysmal nocturnal hemoglobinuria (PNH). Absent or markedly diminished expression of GPI-linked antigens is, in the appropriate clinical setting, specific for all patients with PNH. Clinically, PNH is a syndrome characterized by bone marrow failure, acquired hemolytic anemia, and a thrombotic tendency. The molecular genetic lesion responsible for this condition is a somatic mutation of the X-linked pig-a gene within a multipotent hematopoietic stem cell. Due to its rarity, delay in diagnosis is not uncommon for patients with PNH. Once a definitive diagnosis is established, this can make a considerable impact on patient management and prognosis. In this article, we review the complimentary roles that molecular biology and flow cytometry have played in unraveling the genotypic and phenotypic aspects of this unique condition. Cytometry (Comm. Clin. Cytometry) 42:223-233, 2000.

The naturally occurring oncolytic virus (OV), reovirus, replicates in cancer cells causing direct cytotoxicity, and can activate innate and adaptive immune responses to facilitate tumour clearance. Reovirus is safe, well tolerated and currently in clinical testing for the treatment of multiple myeloma, in combination with dexamethasone/carfilzomib. Activation of natural killer (NK) cells has been observed after systemic delivery of reovirus to cancer patients; however, the ability of OV to potentiate NK cell-mediated antibody-dependent cellular cytotoxicity (ADCC) is unexplored. This study elucidates the potential of oncolytic reovirus for the treatment of chronic lymphocytic leukaemia (CLL), both as a direct cytotoxic agent and as an immunomodulator. We demonstrate that reovirus: (i) is directly cytotoxic against CLL, which requires replication-competent virus; (ii) phenotypically and functionally activates patient NK cells via a monocyte-derived interferon-α (IFNα)-dependent mechanism; and (iii) enhances ADCC-mediated killing of CLL in combination with anti-CD20 antibodies. Our data provide strong preclinical evidence to support the use of reovirus in combination with anti-CD20 immunotherapy for the treatment of CLL.

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