Multi‐gene panel testing improves diagnosis and management of patients with hereditary anemias

Abstract

Mutations in more than 70 genes cause hereditary anemias (HA), a highly heterogeneous group of rare/low frequency disorders in which we included: hyporegenerative anemias, as congenital dyserythropoietic anemia (CDA) and Diamond-Blackfan anemia; hemolytic anemias due to erythrocyte membrane defects, as hereditary spherocytosis and stomatocytosis; hemolytic anemias due to enzymatic defects. The study describes the diagnostic workflow for HA, based on the development of two consecutive versions of a targeted-NGS panel, including 34 and 71 genes, respectively. Seventy-four probands from 62 unrelated families were investigated. Our study includes the most comprehensive gene set for these anemias and the largest cohort of patients described so far. We obtained an overall diagnostic yield of 64.9%. Despite 54.2% of cases showed conclusive diagnosis fitting well to the clinical suspicion, the multi-gene analysis modified the original clinical diagnosis in 45.8% of patients (nonmatched phenotype-genotype). Of note, 81.8% of nonmatched patients were clinically suspected to suffer from CDA. Particularly, 45.5% of the probands originally classified as CDA exhibited a conclusive diagnosis of chronic anemia due to enzymatic defects, mainly due to mutations in PKLR gene. Interestingly, we also identified a syndromic CDA patient with mild anemia and epilepsy, showing a homozygous mutation in CAD gene, recently associated to early infantile epileptic encephalopathy-50 and CDA-like anemia. Finally, we described a patient showing marked iron overload due to the coinheritance of PIEZO1 and SEC23B mutations, demonstrating that the multi-gene approach is valuable not only for achieving a correct and definitive diagnosis, but also for guiding treatment.

Molecular diagnostic update in hereditary hemolytic anemia and neonatal hyperbilirubinemia

“…Targeted NGS panels have been evaluated since 2012 with gene counts on these panels varying from 28 to 70. Russo et al recently evaluated 74 patients with hereditary anemias. Their genetic panel, besides using RBC membrane defects and enzyme deficiencies, also included genes associated with hyporegenerative anemias like CDA and DBA.…”

“…Lin et al43 recently used WES to evaluate seven patients with HHA in the Taiwanese population and identified five disease-causing variants in the ANK1, SPTB, and SPTA1 genes.Targeted NGS panels have been evaluated since 201240,44,45 with gene counts on these panels varying from 28 to 70. Russo et al 45 moderate to severe HA).…”

Coinheritance of hereditary ellyptocytosis, pyruvate kinase, and glucose‐6‐phosphate dehidrogenase mutations. A rare anemia diagnostic paradigm

“…Nevertheless, when NGS result changes the original clinical diagnosis, it mostly happens in patients classified as CDA that showed a conclusive diagnosis of anemia due to enzymatic defects, as dyserythropoiesis may be a common morphologic feature. 3 In our case, the initial suspicion was a red blood cell membranopathy, HE, based on specific morphological features in mother's RBCs. Hereditary elliptocytosis is an RBC defect characterized by an abnormal shape, and it is a cause of rare anemia (RA) in Europe.…”

Addressing the diagnostic gaps in pyruvate kinase deficiency: Consensus recommendations on the diagnosis of pyruvate kinase deficiency

“…[70][71][72] The reticulocyte count in not-splenectomized patients is usually increased. In the most severe cases, some erythroblasts may be observed in peripheral blood smear as a consequence of ineffective erythropoiesis.…”

“…80 A particularly high frequency exists among the Pennsylvania Amish (Arg479His) 101 and a 1149 base pair deletion, which results in loss of exon 11, in the Gypsy communities. 71,72,103,104 Indeed, 1 EU Center only performs PKLR gene analysis in this context, whereas 5 Centers perform standard Sanger sequencing methods for the detection of mutations in patients in which decreased PK activity was found. 71,72,103,104 Indeed, 1 EU Center only performs PKLR gene analysis in this context, whereas 5 Centers perform standard Sanger sequencing methods for the detection of mutations in patients in which decreased PK activity was found.…”