The patient had an immunophenotype consistent with refractory anemia with excess blasts in transformation (RAEB-t) according to French– American–British (FAB) classification. <...> To the best of our knowledge, a comparable adult MDS case associated with such a complex karyotype and loss of TP53 was not previously reported. <...> As most of complex aberrations were found simultaneously in all studied malignant cells this may be a hint on an initial one step development of this complex rearrangement by chromothripsis. <...> PARTIAL TRISOMY 1q21-qter AND PARTIAL MONOSOMY 7q21-qter DUE TO A DERIVATIVE CHROMOSOME 7 IN MYELODYSPLASTIC SYNDROME ASSOCIATED WITH SQUAMOUS CELL CARCINOMA: CASE STUDY Wafa A.1 , Moassass F.1 Al Achkar W.1 1 , Liehr T.2 , Aljapawe A.3 , Molecular Biology and Biotechnology Department, Human Genetics Div., Chromosomes lab., Atomic Energy Commission of Syria, Damascus, Syria; 2 Jena, Germany; 3 Jena University Hospital, Institute of Human Genetics, Molecular Biology and Biotechnology Department, Mammalians Biology Div., Flow-cytometry Lab., Atomic Energy Commission of Syria, Damascus, Syria Myelodysplastic syndrome (MDS) comprises a group of clonal stem cell disorders characterized by cytopenia, dysplasia in one or more hematopoietic cell lineages, and ineffective hematopoiesis leading to bone marrow failure, leukemic transformation, and clonal cytogenetic aberrations. <...> These disorders are associated with a high risk of progression to acute myeloid leukemia and thus an overall short survival. <...> Cytogenetic studies play a major role in confirmation of diagnosis and prediction of clinical outcome, and have contributed to the understanding of its pathogenesis. <...> The most common chromosomal abnormalities in MDS include complete and partial monosomy of chromosomes 5 and 7, deletion of 20q and 12p, trisomy 8, and 11q23 aberrations. <...> A less frequent but nonrandom chromosomal abnormality in MDS is partial trisomy involving parts of chromosome 1q. <...> We report a new adult MDS case associated with squamous cell carcinoma (SCC). <...> Banding cytogenetics, refined by array-proven multicolor banding (aMCB) revealed an unbalanced translocation der(7)t(1;7)(q21;q21), which led to partial trisomy of 1q and partial monosomy of 7q <...>