Modern therapeutic protocols in acute leukemias risk stratify disease based on genetic characterization of the neoplastic cells and their response to treatment. Genetic characterization is routinely performed by cytogenetic testing of leukemic cells and is a standard component of modern risk-adapted therapy in acute lymphoblastic leukemia (ALL). High-throughput technologies like RNA sequencing have identified multiple novel subtypes in recent years. The cytogenetic strategy using GTG and fluorescent in-situ hybridization (FISH) has to be adapted to identify not only the primary principal chromosomal abnormalities but also the novel subtypes. In the review, we describe a systematic comprehensive cytogenetic strategy that integrates information from immunophenotyping, flow-based DNA ploidy, and karyotyping complemented by targeted FISH studies to identify more than 70% of genetic abnormalities described in B cell precursor ALL. The simplified strategy includes a four-probe FISH and flow ploidy strategy, ± karyotyping that identifies high risk (KMT2A, BCR::ABL1, hypodiploidy, iAMP21) and standard risk (ETV6::RUNX1 and high hyperdiploid) cytogenetic groups. The extended FISH panel includes probes targeting MEF2D, ZNF384, and CRLF2 rearrangements that are used intuitively on integrating the immunophenotyping features that characterize these entities. The strategy also includes a systematic approach to identify masked hypodiploidy integrating targeted FISH analysis directed toward identifying monosomies of chromosomes 7, 15, and 17 and flow cytometry-based DNA ploidy analysis. The recently described PH-like ALL is characterized by ABL class fusions and rearrangements of CRLF2 and JAK2 genes. FISH analysis using break-apart probes can be used to identify these aberrations. The cytogenetic approach also includes FISH analysis to identify intragenic and whole gene deletions of the IKZF1 genes that identify a subset of patients associated with high risk of treatment failure.

Introduction:Acquired immunodeficiency Syndrome (AIDS) is caused by Human Immunodeficiency virus leading to profound immunosuppression and its consequences. Depletion of CD4+ T cells is a hallmark of AIDS apart from anaemia, leucopenia and thrombocytopenia. Monitoring of CD4 count is crucial for an effective treatment. Absolute lymphocyte count (ALC) less than 1000/µl i.e. lymphopenia correlates with lower CD4 counts as per various studies and recommendation by the WHO. Detection of lymphopenia and measurement of ALC are routinely obtained parameters using a basic haematology analyser. This study was done to evaluate the role of absolute lymphocyte count (ALC) as an alternative to CD4 count in HIV positive patients. Materials and Methods: This prospective observational study was conducted for the period of two years in the department of Pathology of a tertiary care hospital in western India. 110 HIV positive patients consenting to be the part of the study were included. Complete blood counts (CBC), CD4 and CD8 counts were done for all patients following stringent quality control protocols. Statistical analysis was done to evaluate the correlation between various parameters. Results : 65.5% cases had lymphopenia with an absolute CD4 count <200cells/µl. Using ROC curve, we found that ALC of less than 575/µl has a significant statistical association with CD4 count of less than 200/µl.Correlation of lymphopenia with CD4:CD8 ratio was not found to be statistically significant in our study. Conclusion : ALC can be considered as a cost effective alternative to absolute CD4 counts in the monitoring of HIV positive patients.

Plasma cell dyscrasias are a heterogeneous group of neoplasms characterized by abnormal proliferation of plasma cells with or without over production of monoclonal immunoglobulins. Chromosomal abnormalities are acquired either early in the course of the disease or during disease progression. Plasma cell dyscrasias are categorized into multiple cytogenetic subtypes that form an integral component of risk-stratified treatment protocols. The primary genetic events are IgH gene translocations and non-random gains of chromosomes 3/5/7/9/11/15/19 and or 21. The secondary genetic events consist of chromosome 1 abnormalities (1p deletion and 1q gain or amplification), deletion 17p/TP53, deletion 13q, and MYC gene rearrangements. Plasma cells being at the end of differentiation spectrum of B cells, have low proliferative potential precluding the use of karyotyping in identification of chromosomal abnormalities. Analysis of enriched plasma cells using interphase fluorescent in situ hybridization (FISH) is the technique of choice for identifying these abnormalities. It is essential to enrich plasma cells before the FISH analysis, and numerous plasma cell enrichment techniques have been described. In the paper, we review the cytogenetic approach to identify clinically significant genetic aberrations including the effective use of FISH panels and plasma cell enrichment techniques.