<prompt> Answer this question truthfullyWhat is the pathophysiological mechanism behind T-cell prolymphocytic leukemia?  <response>: <reason> T-PLL has the immunophenotype of a mature post-thymic T-lymphocyte, and the neoplastic cells are typically positive for pan-T antigens CD2, CD3, and CD7 and negative for TdT and CD1a. The immunophenotype CD4 CD8 - is present in 60 of cases, the CD4 CD8 immunophenotype is present in 25, and the CD4 - CD8 immunophenotype is present in 15 of cases.Clonal TCR gene rearrangements for the γ and δ chains are typically found. The most frequent chromosomal abnormality is the inversion of chromosome 14, specifcally inv 14q11;q32. This is found in 80 of cases, while 10 of cases show a reciprocal translocation of chromosome 14 t14;14q11;q32. Also, abnormalities of chromosome 8 are seen approximately 75 of patients, including idic 8p11, t8;8p11-12;q12, and trisomy 8. T-cell prolymphocytic leukemia is a uncommon T- cell malignancy. It arises from mature post- thymic T-cell, which are normally involved in in cell-mediated immunity. It is a relatively aggressive malignancy, characterized by marked lymphocytosis and involving peripheral blood, liver, spleen and bone marrow. Factors playing role in the pathogenesis of these cells are: Mutations in chromosome 14 Mutations in chromosome 8 Mutations in tumor suppressor gene 11q23, at the ataxia telangiectasia mutated ATM locus Inversion of chromosome 14 14q11 TCR gene rearrangements for the γ and δ chainsFactors Involved in the Pathophysiology of T-cell Pro-Lymphocytic Leukemia Genetic Factors Association with different Immunophenotypes Different types of genetic abnormalities are as follows, mostly involve chromosme 14: Inv14 t14;14q11;q32 tX;14q28;q11 which involves a homolog of TCL1, MTCP1 mature T cell proliferation 1 gene Chromosome 8 defects: idic8p11 t8;8 Trisomy 8q Del12p13 Abnormalities in chromosome 17 Deletions in chromosome 6 Deletion of TP53 gene Activating mutation in Tyrosine kinase of Jak3 Deletions or missense mutations at the ataxia telangiectasia mutated ATM locus 11q23 T-cell prolymphocytic leukemia cells express different markers including: CD52 strong association Pan-T cell markers such as: CD2 CD3 might be low or high level CD7 Oncogene TCL1 CD4CD8- present in 60 of cases CD4CD8 present in 25, unique for T-cell prolymphocytic leukemia CD4-CD8 15 of cases Negative terminal deoxynucleotidyl transferase TdT 