Cintia do Couto Mascarenhas

High Frequency of Copy-Neutral Loss of Heterozygosity in Patients with Myelofibrosis

Myelofibrosis is the rarest and most severe type of Philadelphia-negative classical myeloproliferative neoplasms. Although mutually exclusive driver mutations in JAK2, MPL, or CALR that activate JAK-STAT pathway have been related to the pathogenesis of the disease, chromosome abnormalities have also been associated with the phenotype and prognosis of the disease. Here, we report the use of a chromosomal microarray platform consisting of both oligo and SNP probes to improve the detection of chromosome abnormalities in patients with myelofibrosis. Sixteen patients with myelofibrosis were tested, and the results were compared to karyotype analysis. Driver mutations in JAK2, MPL, or CALR were investigated by PCR and MLPA. Conventional cytogenetics revealed chromosome abnormalities in 3 out of 16 cases (18.7%), while chromosomal microarray analysis detected copy-number variations (CNV) or copy-neutral loss of heterozygosity (CN-LOH) alterations in 11 out of 16 (68.7%) patients. These included 43 CN-LOH, 14 deletions, 1 trisomy, and 1 duplication. Ten patients showed multiple chromosomal abnormalities, varying from 2 to 13 CNVs or CN-LOHs. Mutational status for JAK2, CALR, and MPL by MLPA revealed a total of 3/16 (18.7%) patients positive for the JAK2 V617F mutation, 9 with CALR deletion or insertion and 1 positive for MPL mutation. Considering that most of the CNVs identified were smaller than the karyotype resolution and the high frequency of CN-LOHs in our study, we propose that chromosomal microarray platforms that combine oligos and SNP should be used as a first-tier genetic test in patients with myelofibrosis.

Correlations with Point Mutations and Severity of Hemolitic Anemias: The Example of Hereditary Persistence of Fetal Hemoglobin with Sickle Cell Anemia and Beta Thalassemia

Hemolytic anemias are a group of diseases characterized by a reduction in red blood cells (RBC) life span mainly caused by a deregulation in the hemoglobin formation. Among these diseases, Sickle Cell Disease (SCD) and Beta Thalassemia (Thal) are the most common disorders involved in the premature destruction of RBC. Understanding the molecular mechanisms involved in the outcome of these diseases as well as the metabolic pathways surrounding its onset constitutes a very useful approach to target treatment strategies for such diseases. In this chapter we will discuss the state-of-the-art aspects about this theme highlighting the importance of several point mutations in hemolytic anemia using  thalassemia and sickle cell disease as examples. In addition, the molecular aspects involved in the Hereditary Persistence of Fetal Hemoglobin (HPFH), also an important disorder caused by point mutations and deletions, and its association with the severity of Thal and SCD will be also discussed. In this context lies the manifestation of better prognostic to patients having an increase in fetal hemoglobin and SCD or Thal concomitantly. Therefore a parallel discussion towards the advances currently described in the literature and associations of gene expression and different drugs that increase the production of fetal hemoglobin (HbF) are pointed out as a mechanism to improve the quality of life of SCD and Thal patients.