Results of local implementation of next generation sequencing (NGS) for diagnosis of inherited thrombocytopenias (IT) in Argentina.

KAMIYA LJ; GANIEWICH D; MARTA RF; GOETTE NP; DE LUCA G; BASAK N; VEBER E; DONATO H; NEGRO F; ALTUNA D; MARTI A; ARRIETA ME; LAGROTTA P; SOLORZANO D; LLERA A; HELLER PG; GLEMBOTSKY AC

Congreso; Congress of the International Society on Thrombosis and Haemostasis (ISTH); 2023

IT are rare heterogenous disorders caused by germline variants in >50 genes. Although NGS has facilitated IT diagnosis, its application in resource-limited settings remains challenging.We describe our experience after local implementation of exome sequencing (WES) for IT diagnosis in Argentina in the setting of a research project. Twenty probands were included after ethical approval. WES was performed by Illumina. Variant calling and annotation were done using bioinformatic tools and variants from a virtual panel of Tier 1 IT genes were selected for curation and confirmed by Sanger sequencing. Phenotypic characterization and segregation analysis (15 additional individuals) were performed.Twenty-one variants were found in 10 genes (Table 1), 6 of them pathogenic (P) and 10, likely pathogenic (LP) (ACMG guidelines), yielding a diagnostic rate of 70% (14/20 pedigrees). Variants of uncertain significance (VUS) (n=5) were found in 4 families, 3 highly suspicious of being IT-related. No causative variants were found in genes outside the IT panel. Phenotype matched the genetic diagnosis in 79%, while in 21%, with no previous clinical suspicion, WES was essential for diagnosis. Funding provided by a national research agency was instrumental for this initiative, allowing a genetic diagnosis at no cost for the patient. The choice of WES, rather than a NGS targeted panel, was appropriate in our setting, as it required no specific set-up for IT and may be dynamically updated. Limited resources led us to carefully select patients with high suspicion of IT, avoiding inadvertent inclusion of patients with non-inherited forms of thrombocytopenia, which led to a relatively high diagnostic rate. In conclusion, these results indicate the feasibility of this approach in countries with limited resources. This project helped build local capacities and will cover an unmet medical need in our region.