Page 23 - Educacional Ponenecias Congreso SEHH-STH 2020

– Differentiation between α-thalassemia (−α/−α) α-thalassemia (−−/αα), δ+β-thalassemia or large β-gene cluster deletions (δβ-thal or γδβ-thal) in pres- ence of microcytic hypochromic anemia and normal quantification of HbA2.
– Identification of unstable Hbs, Hb-M or high affinity Hbs, when they are silent in electrophoresis or HPLC.
• Enzymopathies: in patients with a high reticulocyte count, because it interferes with the measurement of the enzyme.
• Membranopathies: identification of pathogenic variants in PIEZO1 or KCNN4 genes, as splenectomy is contraindicated in hereditary xerocytosis, due to in- creased risk of thromboembolic complications.
❯ Next generation sequencing (NGS)
Accurate diagnosis of congenital RBC disorders can be challenging because the clinical features may overlap with different etiologies and it is not possible to distin- guish between them using conventional biochemical and molecular techniques. Sanger sequencing is not useful for the diagnoses of complex, multi-gene disor- ders or those with locus heterogeneity.
The wide use of NGS, either whole genome sequenc- ing (WGS), whole exome sequencing (WES) or target- ed gene panels, applied to the study of RBC disorders allowed to the identification of new genes, new vari- ants and also to the detection of interaction of patho- genic variants in different genes causing disorders with complex phenotypes.
RBC disorders’ targeted NGS panels (Table 1) improved the precise diagnosis of CHAs and other RBC disorders, reducing time to diagnosis and ameliorating differential diagnosis in terms of identification of new causative or modifier variants. Moreover, it allowed the identification of polygenic conditions, in which the phenotypic variabil- ity could be explained by the coinheritance of multiple disease genotypes. This enhances management and counselling of the patient and their family.
For those who are familiar with the NGS technology, it is not a surprise to be drowned in lots of variants, patho- genic, likely pathogenic or of unknown significance (VUS). Mutation databases, as HGMD, Varsome or Clin- var are of great help to classify these variants and we should contribute and register the variants (VUS, likely pathogenic or pathogenic) found in our patients.
❯ Bibliography
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