The genetic predisposition to familial hematological malignancies has been previously reported highlighting inherited gene mutations. Several genes have been reported but genetic basis remains not well defined. In this study, we extended our investigation to a potential candidate GATA2 gene which was analyzed by direct sequencing in 119 cases including familial aggregations with a variety of hematological malignancies and sporadic acute leukemia belonging to Tunisian and French populations. We reported a deleterious p.Arg396Gln GATA2 mutation in one patient diagnosed with both sporadic acute myeloid leukemia (AML) and breast cancer. We also reported several GATA2 variations in familial cases. The absence of deleterious mutations in this large cohort of familial aggregations of hematological malignancies may strengthen the hypothesis that GATA2 mutations are an important predisposing factor, although as a secondary genetic event, required for the development of overt malignant disease.

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Isocitrate dehydrogenase IDH 1 and IDH 2 mutations were reported in several cancer forms, especially in hematological malignancies, but were never been investigated in familial aggregation. The aim of this study is to determine whether germline isocitrate dehydrogenase genes mutations are involved.We targeted IDH1 and IDH2 genes in 104 familial cases belonging to Tunisian and French populations, including several forms of hematological malignancies and cosegregated solid tumors.We report one IDH1 variant: c.315 G>T, p.Gly105Gly in 15 % of cases, which was assigned to the worst outcome in several studies. Three IDH2 variants were found, among them, one intronic substitution c.543+45 G>A (rs142033117) and two new variants not previously described: c.389 A>T, p.Lys130Met and c.414 T>C, p.Thr138Thr. The p.Lys130Met was found in one case diagnosed with Waldenstrom's disease with familial history of cancer. The enrolled in silico analysis, the functional study, and the absence of this variant in control population strengthen the hypothesis of its deleterious effect.From an extended number of candidate genes analyzed in familial hematological malignancies, IDH2 might be considerably involved since we reported a potential damaging effect.

IGH gene rearrangement and IGK-Kde gene deletion can be used as molecular markers for the assessment of B lineage acute lymphoblastic leukemia (B-ALL). Minimal residual disease detected based on those markers is currently the most reliable prognosis factor in B-ALL. The aim of this study was to use clonal IGH/IGK-Kde gene rearrangements to confirm B-ALL diagnosis and to evaluate the treatment outcome of Tunisian leukemic patients by monitoring the minimal residual disease (MRD) after induction chemotherapy. Seventeen consecutive newly diagnosed B-ALL patients were investigated by multiplex PCR assay and real time quantitative PCR according to BIOMED 2 conditions. The vast majority of clonal VH-JH rearrangements included VH3 gene. For IGK deletion, clonal VK1f/6-Kde recombinations were mainly identified. These rearrangements were quantified to follow-up seven B-ALL after induction using patient-specific ASO. Four patients had an undetectable level of MRD with a sensitivity of up to 10-5. This molecular approach allowed identification of prognosis risk group and adequate therapeutic decision. The IGK-Kde and IGH gene rearrangements might be used for diagnosis and MRD monitoring of B-ALL, introduced for the first time in Tunisian laboratories.

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Mutations are responsible for familial cancer syndromes which account for approximately 5-10 % of all types of cancers. Familial cancers are often caused by genetic alterations occurring either in tumor suppressor or genomic stability genes such as TP53. In this study, we have analyzed the TP53 gene by direct sequencing approach, in a panel of 18 Tunisian familial hematological malignancies cases including several forms of leukemia, lymphoma and myeloid syndrome and 22 cases of sporadic acute leukemia. In one familial case diagnosed with acute lymphoblastic leukemia, we reported an intronic substitution 559+1 G>A which may disrupt the splice site and impact the normal protein function. Most of the deleterious mutations (Arg158His; Pro282Trp; Thr312Ser) as classified by IARC data base, were commonly reported in ALL cases studied here. The cosegregation of the two variants rs1042522 and rs1642785 was observed in most patients which may be in favor of the presence of linkage disequilibrium. The most defined TP53 mutations found here were identified in acute lymphoblastic leukemia context whereas only 3 % of mutations have been in previous studies. The cosegregation of the two recurrent variant rs1042522 and rs1642785 should be further confirmed.

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