Abstract Number: PB1494
Meeting: ISTH 2020 Congress
Background: Inherited platelet disorders (IPDs) comprise a highly heterogeneous group of disorders affecting platelet number and/or function. For molecular genetic analysis we now established a panel-based next generation sequencing (NGS) approach comprising 90 genes associated with IPDs. Patients of our study (n=21) had moderate to severe bleeding symptoms; especially mucosal bleedings (epistaxis, menorrhagia), hematoma and increased bleeding post-operatively. Von Willebrand factor and coagulation factor disorders were excluded.
Aims: To identify the disease-causing variant in a pilot study of 21 patients with a history of recurrent bleeding episodes and functionally suspected IPD.
Methods: Platelet studies: Morphology (blood smear), aggregometry, flow cytometry. Molecular genetic analyses: Targeting enrichment (Nextera Rapid Custom Enrichment) followed by sequencing on MiSeq (Illumina). Data analysis: SeqPilot (JSI), Alamut® Visual, pathogenicity prediction (SIFT, MutTaster, PolyPhen2, CADD), occurrence in Human Gene Mutation Database. For verification: Sanger sequencing and family genotyping if possible.
Results: NGS achieved a mean coverage from 98% (20x) for the investigated genes and a mean read depth from 578 per nucleotide. We identified 17 variants which were classified as “pathogenic” or “likely pathogenic” in 8 genes. Correlation with platelet functional analyses enabled us to identify class 4 and class 5 pathogenic variant/s for 13 patients.
Conclusions: Panel enrichment is a feasible tool to investigate IPDs in combination with platelet functional analyses. The disease causing variant could be identified for 13 of 21 patients using panel diagnostic. For those patients for whom the platelet phenotype indicated a specific platelet disorder, we could identify the disease causing variant in the suspected candidate genes in all cases. For the patient cohort for whom the platelet phenotype did not indicate to a specific platelet disease, we could only identify the disease causing variant in about 33%. The patients for whom the disease causing variant could not be identified, Whole Exome Sequencing will be performed.
To cite this abstract in AMA style:Boeckelmann D, Sobotta F, Fels S, Glonnegger H, Loewecke F, Lenz A, Zieger B. Inherited Platelet Disorders: Identification of Novel Disease Causing Variants Using Next Generation Sequencing [abstract]. Res Pract Thromb Haemost. 2020; 4 (Suppl 1). https://abstracts.isth.org/abstract/inherited-platelet-disorders-identification-of-novel-disease-causing-variants-using-next-generation-sequencing/. Accessed January 21, 2022.
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