Evidence of two different molecular mechanisms as a consequence of an isolated 20q- abnormality in a case of multiple myeloma accompanied with myelodysplastic syndrome.

The deletion of the long arm of chromosome 20 is a characteristic cytogenetic marker of myeloid disorders. Rarely, it is also found in lymphoproliferative diseases, including multiple myeloma (MM). The role of 20q- in MM is not fully understood. In the cases of MM which co-exist with primary or therapy-related dysplasia, this anomaly is mostly linked to the occurrence of myeloid neoplasms. On the other hand 20q- is found as an isolated anomaly in cases with MM that have no dysplastic features or is not accompanied with other hematological diseases which suggests that the 20q deletion is also important for the development of MM. This report describes an isolated 20q- anomaly in a case of a light chain myeloma co-existing with myelodysplastic syndrome (MDS). Fluorescent in situ hybridization (FISH) experiments have demonstrated the presence in the patient's bone marrow of a basic clone (stemline) with deletion of the PTPRT gene (located at 20q13.11) and two sidelines: one with deletion of the PTPRT and MAPRE1 genes (located at 20q11.12) found in the mature granulocytes and one with deletion of PTPRT and duplication of MAPRE1 found in the myeloma cells. These data have indicated that 20q- has appeared in the multipotent precursor cells and affects both myeloid and lymphoid lineage by two different molecular mechanisms - one possibly related to the pathogenesis of the MDS and another to the pathogenesis of the MM.

Philadelphia-positive case negative for JAK2 V617F mutation with hyperdiploidic karyotype: A case report.

Chronic myeloid leukemia (CML) is one of the most common hematological malignancies and accounts for 15-20% of all leukemia cases. The cytogenetic marker of CML is the presence of Philadelphia chromosome (Ph) in >95% of patients. The current case reports a 83-year old woman who was directed to the genetic laboratory for a cytogenetic and molecular-genetic analysis suspected to be Ph positive [(+)]. Karyotype analysis of a bone marrow sample revealed a hyperdiploid karyotype in a part of Ph (+) cells with additional chromosomes 8, 10 and 12. Restriction analysis for V617F JAK2 mutation was negative, while the quantitative RT-qPCR assay indicated BCR-ABL/ABL transcript at the level of 120% International Scale (IS). Generally cytogenetic complexities are important in the prognostic evaluation of CML. Besides the Ph chromosome, a variet of chromosomal aberrations may be associated with CML. A total of 5-10% of these cases show complex translocations involving another chromosome. The current case is Ph(+) demonstrating an additional hyperdiploid karyotype clone with three additional autosomes (8, 10 and 12). This case highlights the significance of cytogenetic abnormalities on the prognosis of CML.