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A comprehensive targeted next-generation sequencing panel for genetic diagnosis of patients with suspected inherited thrombocytopenia.

ABSTRACT: Background:Inherited thrombocytopenias (ITs) are a heterogeneous group of disorders characterized by low platelet counts and often disproportionate bleeding with over 30 genes currently implicated. Previously the UK-GAPP study using whole exome sequencing (WES) identified a pathogenic variant in 19 of 47 (40%) patients of which 71% had variants in genes known to cause IT. Aims:To employ a targeted next-generation sequencing platform to improve efficiency of diagnostic testing and reduce overall costs. Methods:We have developed an IT-specific gene panel as a pre-screen for patients prior to WES using the Agilent SureSelectQXT transposon-based enrichment system. Results:Thirty-one patients were analyzed using the panel-based sequencing, of which; 10% (3/31) were identified with a classified pathogenic variant, 16% (5/31) were identified with a likely pathogenic variant, 51% (16/31) were identified with variants of unknown significance, and 23% (7/31) were identified with either no variant or a benign variant. Discussion and Conclusion:Although requiring further clarification of the impact of the genetic variations, the application of an IT-specific next generation sequencing panel is an viable method of pre-screening patients for variants in known IT-causing genes prior to WES. With an added benefit of distinguishing IT from idiopathic thrombocytopenic purpura (ITP) and the potential to identify variants in genes known to have a predisposition to hematological malignancies, it could become a critical step in improving patient clinical management.

SUBMITTER: Johnson B

PROVIDER: S-EPMC6178765 | biostudies-literature | 2018 Oct

REPOSITORIES: biostudies-literature

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A comprehensive targeted next-generation sequencing panel for genetic diagnosis of patients with suspected inherited thrombocytopenia.

Johnson Ben B Doak Rachel R Allsup David D Astwood Emma E Evans Gillian G Grimley Charlotte C James Beki B Myers Bethan B Stokley Simone S Thachil Jecko J Wilde Jonathan J Williams Mike M Makris Mike M Lowe Gillian C GC Wallis Yvonne Y Daly Martina E ME Morgan Neil V NV

Research and practice in thrombosis and haemostasis 20181008 4

<h4>Background</h4>Inherited thrombocytopenias (ITs) are a heterogeneous group of disorders characterized by low platelet counts and often disproportionate bleeding with over 30 genes currently implicated. Previously the UK-GAPP study using whole exome sequencing (WES) identified a pathogenic variant in 19 of 47 (40%) patients of which 71% had variants in genes known to cause IT.<h4>Aims</h4>To employ a targeted next-generation sequencing platform to improve efficiency of diagnostic testing and ...[more]

PMID: 30349881

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Project description:PurposeInherited peripheral neuropathies (IPN) represent a large heterogenous group of hereditary diseases with more than 100 causative genes reported to date. In this context, targeted next-generation sequencing (NGS) offers the opportunity to screen all these genes with high efficiency in order to unravel the genetic basis of the disease. Here, we compare the diagnostic yield of targeted NGS with our previous gene by gene Sanger sequencing strategy. We also describe several novel likely pathogenic variants.Design and participantsWe have completed the targeted NGS of 81 IPN genes in a cohort of 123 unrelated patients affected with diverse forms of IPNs, mostly Charcot-Marie-Tooth disease (CMT): 23% CMT1, 52% CMT2, 9% distal hereditary motor neuropathy, 7% hereditary sensory and autonomic neuropathy and 6.5% intermediate CMT.ResultsWe have solved the molecular diagnosis in 49 of 123 patients (~40%). Among the identified variants, 26 variants were already reported in the literature. In our cohort, the most frequently mutated genes are respectively: MFN2, SH3TC2, GDAP1, NEFL, GAN, KIF5A and AARS. Panel-based NGS was more efficient in familial cases than in sporadic cases (diagnostic yield 49%vs19%, respectively). NGS-based search for copy number variations, allowed the identification of three duplications in three patients and raised the diagnostic yield to 41%. This yield is two times higher than the one obtained previously by gene Sanger sequencing screening. The impact of panel-based NGS screening is particularly important for demyelinating CMT (CMT1) subtypes, for which the success rate reached 87% (36% only for axonal CMT2).ConclusionNGS allowed to identify causal mutations in a shorter and cost-effective time. Actually, targeted NGS is a well-suited strategy for efficient molecular diagnosis of IPNs. However, NGS leads to the identification of numerous variants of unknown significance, which interpretation requires interdisciplinary collaborations between molecular geneticists, clinicians and (neuro)pathologists.

Project description:BackgroundDefects in the development of the first and second pharyngeal arches and their derivatives result in abnormal formation of the craniofacial complex, consequently giving rise to facial dysostoses (FDs). FDs represent a group of rare and highly heterogeneous disease entities that encompass mandibulofacial dysostoses (MFDs) with normal extremities and acrofacial dysostoses (AFDs) with limb anomalies in addition to craniofacial defects.MethodsWe examined 11 families with variable clinical symptoms of FDs, in most of which only one member was affected. We applied two custom gene panels-first comprising 37 genes related to the genetic disorders of craniofacial development such as FDs (On-Demand AmpliSeq Thermo Fisher Scientific gene panel with two primer pools) and second composed of 61 genes and 11 single nucleotide variants (SNVs) known to be involved in the development of skull malformations, mainly in the form of craniosynostoses (SureSelect Agilent Technologies). Targeted next-generation sequencing (NGS) was performed using the Ion Torrent S5 platform. To confirm the presence of each detected variant, we have analyzed a genomic region of interest using Sanger sequencing.ResultsIn this paper, we summarized the results of custom targeted gene panel sequencing in the cohort of sixteen patients from 11 consecutive families affected by distinct forms of FDs. We have found three novel pathogenic variants in the TCOF1 gene-c.2145_2148dupAAAG p.(Ser717Lysfs ∗42), c.4370delA p.(Lys1457Argfs ∗118), c.83G>C p.(Arg28Pro) causing Treacher Collins syndrome type 1, two novel missense variants in the EFTUD2 gene-c.491A>G p.(Asp164Gly) and c.779T>A p.(Ile260Asn) in two female patients affected by acrofacial dysostosis Guion-Almeida type, one previously reported-c.403C>T (p.Arg135Cys), as well as one novel missense variant-c.128C>T p.(Pro43Leu) in the DHODH gene in the male patient with Miller syndrome and finally one known pathogenic variant c.574G>T p.(Glu192∗) in the SF3B4 gene in the patient with Nager syndrome.ConclusionOur study confirms the efficiency and clinical utility of the targeted gene panel sequencing and shows that this strategy is suitable and efficient in the molecular screening of variable forms of FDs.

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A comprehensive targeted next-generation sequencing panel for genetic diagnosis of patients with suspected inherited thrombocytopenia.

Publications

A comprehensive targeted next-generation sequencing panel for genetic diagnosis of patients with suspected inherited thrombocytopenia.

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