Molecular Characterization of <b>β</b>-Thalassemia in the Czech and Slovak Populations: Mediterranean, Asian and Unique Mutations

<p>β-Thalassemia (β-thal) is considered rare in Central Europe. As in other malaria-free regions, the presence of β-thal in Central Europe reflects historical and recent immigration, and demographic changes that have influenced the genetic variability of the current populations living in this area. This study assesses the frequency and spectrum of mutations on the β-globin gene in Czech and Slovak subjects with clinical symptoms of thalassemia. The results of the initial part of this research were published more than two decades ago; the aim of this study was to update these original reports. During the period from 2002 to 2015, 400 cases from Czech and Slovak hematological centers were analyzed. Twenty-nine β-thal mutations, identified in 356 heterozygotes from 218 unrelated families, involve five unique mutations including a recently described insertion of a transposable L1 element into the β-globin gene. One mutation described here is reported for the first time. Most of the mutations were of Mediterranean origin and accounted for 82.0% of cases. All but one case studied were heterozygous carriers, manifesting β-thal minor, with rare exceptions represented by the rare (β⁰) codons 46/47 (+G) (<i>HBB</i>: c.142_142dupG) mutation associated with an α-globin gene quadruplication and by dominantly inherited β-thal with a more severe phenotype. One double heterozygous β-thal patient was a recent immigrant from Moldavia. The list of δβ-thal alleles (26 carriers, 16 families) contains Hb Lepore and two types of δβ⁰-thal deletions. In the past, genetic drift and migration as well as recent immigrations were responsible for the introduction of Mediterranean alleles, while several mutations described in single families were of local origin.</p

Interferon-α Revisited: Individualized Treatment Management Eased the Selective Pressure of Tyrosine Kinase Inhibitors on BCR-ABL1 Mutations Resulting in a Molecular Response in High-Risk CML Patients.

Bone marrow transplantation or ponatinib treatment are currently recommended strategies for management of patients with chronic myeloid leukemia (CML) harboring the T315I mutation and compound or polyclonal mutations. However, in some individual cases, these treatment scenarios cannot be applied. We used an alternative treatment strategy with interferon-α (IFN-α) given solo, sequentially or together with TKI in a group of 6 cases of high risk CML patients, assuming that the TKI-independent mechanism of action may lead to mutant clone repression. IFN-α based individualized therapy decreases of T315I or compound mutations to undetectable levels as assessed by next-generation deep sequencing, which was associated with a molecular response in 4/6 patients. Based on the observed results from immune profiling, we assumed that the principal mechanism leading to the success of the treatment was the immune activation induced with dasatinib pre-treatment followed by restoration of immunological surveillance after application of IFN-α therapy. Moreover, we showed that sensitive measurement of mutated BCR-ABL1 transcript levels augments the safety of this individualized treatment strategy

Patient’s characteristics.

<p>Patient’s characteristics.</p

Summary of sequential lines of treatment, therapy responses and mutation status.

<p>Summary of sequential lines of treatment, therapy responses and mutation status.</p

Flow cytometry results.

<p>Flow cytometry results.</p

Dynamics of total and mutated BCR-ABL1 transcript levels.

<p>(A) Patient no 1: The patient achieved MMR on solo IFN-α and maintained MMR for 88 months; the T315I mutation was persistently undetectable for 62 months due to the overall low levels of total BCR-ABL1 transcripts. (B) Patient no 2: Compound mutations M351T/F317L (100%) developed after sequential therapy with imatinib and dasatinib. The patient has now been on IFN-α/nilotinib therapy with undetectable mutations for 29 months. MR⁵ was achieved on the 15^th month of the combined treatment. (C) Patient no 3: Poor compliance to imatinib treatment within the 24^th– 30^th month; the T315I mutation burden decreased on solo IFN-α therapy down to undetectable levels after the combination of IFN-α and nilotinib. The patient achieved MR⁵ in the 22^nd month from IFN-α treatment initiation. (D) Patient no 4: The T315I mutation decreased on solo IFN-α therapy and was not detected for the subsequent 46 months on solo nilotinib therapy. The relatively slow reduction of the BCR-ABL1 transcript level and MMR achievement might have been caused by a problematic compliance to nilotinib. (E) Patient no 5: The T315I mutation decreased on solo IFN-α therapy, but the F317L and E255V mutations appeared and expanded. Death of this patient was related to lung tuberculosis. (F) Patient no 6: IFN-α therapy did not contribute to the T315I reduction and response improvement. Therefore, the patient has been switched to ponatinib with CCgR achievement after 7 months from ponatinib treatment initiation. IMA-imatinib, NILO-nilotinib, DASA-dasatinib, IFN-α –interferon alpha, HU-hydroxyurea, PONA-ponatinib. Note: A mutation burden of 0% represented undetectable levels of mutated BCR-ABL1 transcripts when the sequencing depth was 1,000 to 8,000 sequence reads per each nucleotide position.</p