A new complex karyotype in a unique de novo myelodysplastic syndrome case involving ten chromosomes and monoallelic loss of TP53

Abstract Myelodysplastic syndrome (MDS) is a group of clonal stem cell disorders characterized by cytopenia, dysplasia in one or more cell lineages, and ineffective hematopoiesis. MDS is associated with high risk of progression to acute myeloid leukemia. At initial diagnosis, clonal cytogenetic aberrations are present in 40–70% of patients with de novo (primary) MDS and in 65–95% of patients with therapy-associated ones (t-MDS). Most commonly observed abnormalities present in MDS are monosomy 5 and 7, trisomy 8, deletions of long arm of chromosome 20 as well as complex karyotypes. Loss or gain of chromosomal material is known to be related to disease development and progression. In a de novo adult MDS case banding cytogenetics, refined by array-proven multicolor banding (aMCB) revealed a unique complex karyotype involving ten chromosomes that include del(5q), del(7q), deletions in parts of both chromosomes 10, and a dic(7;17). Interestingly, the dic(7;17) leads to monosomy of the tumor suppressor gene TP53 . 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.