1. Introduction
Non-Hodgkin lymphomas (NHL) are a heterogeneous group of malignancies that originate from the lymphatic system and, in particular, from either immature or mature/peripheral lymphocytes [1]. Their classification is primarily based on the cell of origin (i.e., B or T cell) or histogenesis, which is further narrowed into different categories based on morphology, phenotype, genetic and clinical characteristics. Therefore, the diverse types of NHL significantly vary in both their clinical features, being defined as either indolent or aggressive, and pathobiology. As far as the latter is concerned, in the last decade tremendous advances have been made in the understanding of the molecular pathogenesis of lymphomas leading in some instances to a real molecular classification, as in the case of diffuse large B-cell lymphomas (DLBCL) (see below) [2].
Genetic aberrations, such as copy number variants (CNVs) and translocations have been shown to be specifically correlated with certain human cancers and, quite often, with hematological malignancies including lymphomas. In this regard, various technological advances in molecular analyses have greatly enhanced our ability to identify specific genetic aberrations in any tumor type [3]. In particular, the introduction of high-throughput technologies such as microarrays allowed fast and relatively cheap extensive studies leading to the discovery of several genetic aberrations [3]. Importantly, their identification has a practical impact, having an important role in diagnosis, prognosis, and subsequent choice of therapy in cancers [4,5,6,7,8].
Traditionally, genomic lesions in cancer specimens have been recognized using metaphase cytogenetic (MC), fluorescent in situ hybridization (FISH) and Sanger sequencing. However, though still relevant, these methods impose several limitations like the dependence on the availability of dividing cells and resolution restrictions (MC) [9]. Albeit the abilities of FISH and sequencing in triumphing over some of the above mentioned disadvantages like the lack of dependency upon dividing cells, they are limited in terms of being applicable to the candidate regions, making them unsuitable for the genome-wide screenings [10].
These drawbacks were further overcome with the introduction of high resolution methods such as comparative genomic hybridization (CGH) and SNP microarrays, enabling us with genome-wide molecular karyotyping possibilities. Besides the lack of need for dividing cells, above all SNP arrays provide us with the opportunity of the detection of several types of genetic lesions, by progressively expanding the resolution of DNA analysis (explained below) [11,12,13,14,15,16].
Here, we highlighted the most recent findings obtained from global analysis of genetic aberrations in some of the most common subtypes of NHL of B- and T-cell origin, including DLBCL, follicular lymphoma (FL), mantel cell lymphoma (MCL), marginal zone B cell lymphoma (MZL), and peripheral T cell lymphomas (PTCLs).