Targeted next-generation sequencing identified novel mutations associated with hereditary anemias in Brazil

Abstract

Hereditary anemias are a group of heterogeneous disorders including hemolytic anemias and hyporegenerative anemias, as congenital dyserythropoietic anemia (CDA). Causative mutations occur in a wide range of genes leading to deficiencies in red cell production, structure, or function. The genetic screening of the main genes is important for timely diagnosis, since routine laboratory tests fail in a percentage of the cases, appropriate treatment decisions, and genetic counseling purposes. A conventional gene-by-gene sequencing approach is expensive and highly time-consuming, due to the genetic complexity of these diseases. To overcome this problem, we customized a targeted sequencing panel covering 35 genes previously associated to red cell disorders. We analyzed 36 patients, and potentially pathogenic variants were identified in 26 cases (72%). Twenty variants were novel. Remarkably, mutations in the SPTB gene (βspectrin) were found in 34.6% of the patients with hereditary spherocytosis (HS), suggesting that SPTB is a major HS gene in the Southeast of Brazil. We also identified two cases with dominant HS presenting null mutations in trans with α-LELY in SPTA1 gene. This is the first comprehensive genetic analysis for hereditary anemias in the Brazilian population, contributing to a better understanding of the genetic basis and phenotypic consequences of these rare conditions in our population.

Genotype-phenotype relationship in pyruvate kinase deficiency: baseline transfusion dependence and splenectomy response

“…The classification of mutations we propose has limitations that can be seen in several examples. Some mutations may be more severe than predicted, as seems to be the case with the Gly511Glu missense mutation, which we categorized as mild but is associated with severe phenotypes both in our cohort and in the 2 studies already published 21,22 . Such mutation does not affect any key amino acids for enzyme function nor does it predict splicing changes.…”

Targeted Next Generation Sequencing and Diagnosis of Congenital Hemolytic Anemias: A Three Years Experience Monocentric Study

“…The advent and recent progresses on next generation sequencing (NGS) technologies has radically changed the diagnostic approach to CHAs, often placing the genetic analysis as a first line screening tool; different NGS strategies have been developed in the last years including targeted panels and whole exome sequencing (WES), with a progressive reduction of costs that allowed their routinely use (Steinberg-Shemer and Tamary, 2020;Russo et al, 2020). Targeted-NGS panels have been developed and applied by several groups, being currently the preferred approach for the molecular diagnosis of CHAs; custom panels include different numbers of genes and have been reported to have a wide range of diagnostic efficacy (38-90%) depending on the number of genes included and on the characteristics of the patients studied (Agarwal et al, 2016;Del Orbe Barreto et al, 2016;Niss et al, 2016;Roy et al, 2016;Russo et al, 2018;Shefer Averbuch et al, 2018;Choi et al, 2019;Kedar et al, 2019a,b;Svidnicki et al, 2020). In this paper we report the 3 years monocentric experience in targeted-NGS and diagnosis of CHAs, and we compare the efficacy of this methodological approach with the conventional laboratory diagnosis.…”

Applying Next-Generation Sequencing Platforms for Pharmacogenomic Testing in Clinical Practice

“…Therefore, a prediction is not feasible easily on the functionality of VUS to interpret the potential effects on the drug responses in a patient. However, because of the lower number of such findings in panels, replication and validation studies using other orthogonal genotyping methods, in silico algorithms, genetic screening for first degree relatives of the proband, and use of GWAS, HapMap, or gnomAD datasets for meta-analysis will be faster and more easier with regard to predicting and confirming the negative or neutral functionality of variants and demonstrating the phenotype associations in the targeted sequencing approaches ( Svidnicki et al, 2020 ).…”