Clinical utility of targeted next-generation sequencing panel in routine diagnosis of hereditary hemolytic anemia: A national reference laboratory experience

Hereditary Spherocytosis: Can Next-Generation Sequencing of the Five Most Frequently Affected Genes Replace Time-Consuming Functional Investigations?

Congenital defects of the erythrocyte membrane are common in northern Europe and all over the world. The resulting diseases, for example, hereditary spherocytosis (HS), are often underdiagnosed, partly due to their sometimes mild and asymptomatic courses. In addition to a broad clinical spectrum, this is also due to the occasionally complex diagnostics that are not available to every patient. To test whether next-generation sequencing (NGS) could replace time-consuming spherocytosis-specific functional tests, 22 consecutive patients with suspected red cell membranopathy underwent functional blood tests. We were able to identify the causative genetic defect in all patients with suspected HS who underwent genetic testing (n = 17). The sensitivity of the NGS approach, which tests five genes (ANK1 (gene product: ankyrin1), EPB42 (erythrocyte membrane protein band4.2), SLC4A1 (band3), SPTA1 (α-spectrin), and SPTB (β-spectrin)), was 100% (95% confidence interval: 81.5-100.0%). The major advantage of genetic testing in the paediatric setting is the small amount of blood required (<200 µL), and compared to functional assays, sample stability is not an issue. The combination of medical history, basic laboratory parameters, and an NGS panel with five genes is sufficient for diagnosis in most cases. Only in rare cases, a more comprehensive functional screening is required.

Acquired elliptocytosis in chronic myeloid neoplasms: An enigmatic relationship to acquired red cell membrane protein and genetic abnormalities

Nineteen reports of 41 cases of acquired red cell elliptocytosis associated with a chronic myeloid neoplasm are described. Although the majority of cases have an abnormality of the long arm of chromosome 20, del(q20), several cases do not. Moreover, in one case a specific qualitative abnormality of red cell protein band 4.1(4.1R) was reported; however, several subsequent cases could find no abnormality of a red cell membrane protein or found a different abnormality, usually quantitative. Thus, this striking red cell phenotypic feature, acquired elliptocytosis, seen in myelodysplastic syndrome and other chronic myeloproliferative diseases, closely simulating the red cell phenotype of hereditary elliptocytosis, has an unexplained genetic basis, presumably as the result of an acquired mutation(s) in some chronic myeloid neoplasms.

Molecular diagnosis of hereditary hemolytic anemias: Recent updates

Hereditary hemolytic anemia (HHA) is a heterogeneous group of disorders due to genetically caused defects in red blood cell membrane structure, enzymes, heme and globin synthesis, erythroid proliferation, and differentiation. Traditionally, the diagnostic process is complex and includes a plethora of tests from routine to highly specialized ones. The inclusion of molecular testing has significantly improved the diagnostic yield. The value of molecular testing is broader than just rendering the correct diagnosis, as it may also guide therapeutic decisions. As more molecular modalities become available for clinical use, it is imperative to understand their benefits and disadvantages pertaining to the HHA diagnostics. Re-evaluation of the traditional diagnostic workflow may also bring forth additional benefits. This review focuses on the current state of molecular testing for HHA.