Mounia Bendari

By Mounia Bendari, Nisrine Khoubila, Siham Cherkaoui, Nezha Hda, Meryem Qachouh, Mouna Lamchahab and Asmaa Quessar

Cytogenetic abnormalities are frequently reported in the literature describing the presence of chromosomal rearrangements in important cases of acute myeloid leukemia (AML); the rate can reach 50–60% of cases of AML. Cytogenetic abnormalities represent an important prognosis factor, their analysis is crucial for AML; cytogenetic study permits to classify prognostic groups and indicate the treatment strategy and helps to improve the outcome of these patients and to increase their chances of cure. Hundreds of uncommon chromosomal aberrations from AML exist. This chapter summarizes chromosomal abnormalities that are common and classifies AML according to the World Health Organization (WHO) classifications from 2008 to 2016; we will discuss briefly gene mutations detected in normal karyotype (NK) AML by cutting-edge next-generation sequencing technology, like FLT3-ITD, nucleophosmin (NPM1), CCAAT/enhancer-binding protein alpha (CEBPA), and other additional mutations.

Part of the book: Chromosomal Abnormalities

By Mounia Bendari and Nisrine Khoubila

Myelodysplasia syndromes (MDS) are defined by a heterogeneous group of myeloid malignancies characterized by peripheral blood cytopenia and dishematopoiesis and frequently progress to acute myeloid leukemia. Conventional karyotype has a crucial role in myelodysplastic syndrome (MDS) and is one of items of the International Prognostic Scoring System (IPSS) for patient risk stratification and treatment selection. Approximately 50–60% of cases of MDS present chromosomal abnormalities, like the deletions of chromosome 5q and 7q, trisomy 8, and complex karyotypes. New genomic technologies have been developted, like single-nucleotide polymorphism array and next-generation sequencing. They can identify the heterozygous deletions wich result in haplo-insufficient gene expression (e.g., CSNK1A1, DDX41 on chromosome 5, CUX1, LUC7L2, EZH2 on chromosome 7) involved in the pathogenesis of myelodysplasia syndromes. Genetic abnormalities are multiple, the most recurrent one are involved in the RNA splicing like SF3B1, SRSF2, U2AF1, ZRSR2, LUC7L2, and DDX41. Epigenetic modifications are also identified, such as histone modification as ASXL1, EZH2. Finally, it can be DNA methylation (e.g., TET2, DNMT3A, IDH1/IDH2). On this review we will summarize the most recent progress in molecular pathogenesis of MDS, and try to better understand the pathogenesis of the specific subgroups of MDS patients and applications of discovery of new genetic mutation in the development of new therapeutic.

Part of the book: Cytogenetics

By Mounia Bendari, Sofia Sraidi and Nisrine Khoubila

Acute lymphoblastic leukemia (ALL), can be defined by a family of genetically heterogeneous lymphoid neoplasms derived from B- and T-lymphoid progenitors. ALL constitutes the most common childhood cancer, due to an overproduction of immature lymphoid hematopoietic cells. Genetic analyzes currently provides important information for classifying patients into prognostic groups, genetic analysis also helps to understand the mechanisms of relapse, pharmacogenetics and the development of new potential therapeutic targets, which should help to further improve the results of leukemia. In fact, the new techniques in molecular cytogenetic permits to identify new cryptic abnormalities, these discoveries have led to the development of new therapeutic protocols. The role of cytogenetic analysis is crucial on ALL patient’s management. Karyotyping coupled with FISH analysis identifies recurrent chromosomal abnormalities in ALL, many of these abnormalities have prognostic and treatment impact. This chapter summarizes chromosomal abnormalities that are common and classify ALL according to the World Health Organization (WHO) classifications (2016 revision). We will present the main genetic modifications recently identified as well as the sequence mutations which have helped in the elucidation of the pathogenesis of ALL.

Part of the book: Cytogenetics

By Mounia Bendari, Sofia Sraidi and Nisrine Khoubila

Genetic defects play a major role in pathogenesis of the most of haematological malignancies, including cytogenetic abnormalities, gene mutations, and abnormal gene expression. Our knowledge about the genetics of haematological disorders has been dramatically improved during the past decade, due to revolution of sequencing technologies which have played a crucial role. In this chapter, we describe the techniques commonly employed for elucidating chromosomal aberrations, prognostic impact of recurrent chromosomal abnormalities, and recently updated risk stratification systems. We will summarise the chromosomal abnormalities recently identified on many of haematological diseases such acute myeloid leukaemia, acute lymphoid leukaemia, myelodysplasic syndrome, multiple myeloma, meyloproliferative disease and clarify their impacts on clinical phenotype and prognosis, as well as their role in the pathogenesis of these diseases. The aim of this chapter is to provide a brief overview of the recent progresses in haematological diseases genetics.

Part of the book: Cytogenetics