The implementation of a high-throughput sequencing test for diagnosing inherited bleeding, thrombotic, and platelet disorders: lessons learned from an international study.

T. Bakchoul, H. Schulze, E. Simeoni, W. Ouwehand, E. Turro (1Tübingen, Germany)

Date: 16.02.2017,
Time: 08:00 - 09:15

Objective: Inherited bleeding, thrombotic, and platelet disorders (BPD) are heterogeneous and a molecular analysis for patients with a BPD is often unavailable. The ThromboGenomics is a platform that provides a DNA-based test to diagnose patients suspected of having an inherited BPD.

Methods: A high-throughput sequencing platform was designed targeting 63 genes relevant for BPDs. Sequencing data were analyzed in combination with an analysis approach based on using the Human Phenotype Ontology (HPO) terms for coding phenotype. 300 samples from 13 different countries were enrolled in this study from i) patients with known pathogenic variants (known-group, n=159), ii) patients with phenotypes that strongly indicate a particular disorder (suspected-group, n=61), iii) patients having clinical bleeding or thrombotic problems but normal laboratory coagulation and platelet function tests (uncertain-group, n=76) and iv) 4 samples from unaffected relatives.

Results: All previously determined variants in the know-group were detected (empirical sensitivity 100%). In 56 out of 61 cases from the suspected-group pathogenic (n=29) or likely-pathogenic (n=28) variants that fully or partially explain the disease phenotype were identified (sensitivity 91.8%). In the uncertain-group, genetic defects were found only in 8 out of 76 cases corresponding to a sensitivity of 10.5%. Interestingly, negative Sanger sequencing results were overturned in 3 cases in the suspected- and uncertain-group, respectively, demonstrating that this platform can outperform Sanger sequencing in terms of sensitivity.

Conclusion: These results indicate that the ThromboGenomics platform has an excellent sensitivity to detect known causal variants in known BPD genes. However, the low rate of identified genetic variants in patients with uncertain etiology demonstrates the need for further research into the molecular etiology of uncharacterized BPDs. The BRIDGE-BPD is a research platform which will help identifying novel variants not in the known Tier 1 genes.