Identification of rare defective allelic variants in cases of thiopurine S-methyltransferase deficient activity

2020 ◽  
Vol 21 (17) ◽  
pp. 1217-1226
Author(s):  
Albain Chansavang ◽  
Sadok Maalej ◽  
Céline Narjoz ◽  
Marie-Anne Loriot ◽  
Nicolas Pallet
Keyword(s):  
Next Generation Sequencing ◽  
Rare Variants ◽  
Diagnostic Yield ◽  
Normal Activity ◽  
Critical Issue ◽  
Allelic Variants ◽  
Uncertain Significance ◽  
Discordant Genotype ◽  
Deficient Activity ◽  
Generation Sequencing

Aim: To assess rare TPMT variants in patients carrying a deficient phenotype not predicted by the four more frequent genotypes (*2, *3A, *3B and *3C). Materials & methods: Next-generation sequencing of TPMT in 39 patients with a discordant genotype. Results: None of the variants identified explained the discordances assuming that they are of uncertain significance according to the Clinical Pharmacogenetics Implementation Consortium classification. Two unknown variants were detected and predicted to result in a splicing defect. We show that TPMT*16 and TMPT*21 are defective alleles, and TPMT*8 and TPMT*24 are associated with a normal activity. Conclusion: Whole-exon sequencing for rare  TPMT mutations has a low diagnostic yield. A reassessment of the functional impact of rare variants of uncertain significance is a critical issue.

scholarly journals Diagnostic yield of targeted next generation sequencing in 2002 Dutch cardiomyopathy patients

2021 ◽  
Author(s):  
Mohamed Z. Alimohamed ◽  
LennartF. Johansson ◽  
Anna Posafalvi ◽  
Ludolf G. Boven ◽  
Krista K. van Dijk ◽  
...  
Keyword(s):  
Next Generation Sequencing ◽  
Diagnostic Yield ◽  
Next Generation ◽  
Targeted Next Generation Sequencing ◽  
Generation Sequencing

High diagnostic yield of syndromic intellectual disability by targeted next-generation sequencing

2016 ◽  
Vol 54 (2) ◽  
pp. 87-92 ◽  
Author(s):  
Francisco Martínez ◽  
Alfonso Caro-Llopis ◽  
Mónica Roselló ◽  
Silvestre Oltra ◽  
Sonia Mayo ◽  
...  
Keyword(s):  
Intellectual Disability ◽  
Next Generation Sequencing ◽  
Diagnostic Yield ◽  
Next Generation ◽  
Targeted Next Generation Sequencing ◽  
High Diagnostic Yield ◽  
Generation Sequencing

scholarly journals Next-Generation Sequencing Gene Panels and “Solo” Clinical Exome Sequencing Applied in Structurally Abnormal Fetuses

2021 ◽  
pp. 1-11
Author(s):  
Montse Pauta ◽  
Berta Campos ◽  
Maria Segura-Puimedon ◽  
Gemma Arca ◽  
Alfons Nadal ◽  
...  
Keyword(s):  
Next Generation Sequencing ◽  
Exome Sequencing ◽  
Diagnostic Yield ◽  
Monogenic Disease ◽  
Chromosomal Microarray Analysis ◽  
Next Generation ◽  
Clinical Exome Sequencing ◽  
Gene Panels ◽  
Generation Sequencing ◽  
Structural Anomalies

<b><i>Objective:</i></b> The aim of the study was to assess the diagnostic yield of 2 different next-generation sequencing (NGS) approaches: gene panel and “solo” clinical exome sequencing (solo-CES), in fetuses with structural anomalies and normal chromosomal microarray analysis (CMA), in the absence of a known familial mutation. <b><i>Methodology:</i></b> Gene panels encompassing from 2 to 140 genes, were applied mainly in persistent nuchal fold/fetal hydrops and in large hyperechogenic kidneys. Solo-CES, which entails sequencing the fetus alone and only interpreting the Online Mendelian Inheritance in Man genes, was performed in multisystem or recurrent structural anomalies. <b><i>Results:</i></b> During the study period (2015–2020), 153 NGS studies were performed in 148 structurally abnormal fetuses with a normal CMA. The overall diagnostic yield accounted for 35% (53/153) of samples and 36% (53/148) of the fetuses. Diagnostic yield with the gene panels was 31% (15/49), similar to 37% (38/104) in solo-CES. <b><i>Conclusions:</i></b> A monogenic disease was established as the underlying cause in 35% of selected fetal structural anomalies by gene panels and solo-CES.

scholarly journals Targeted next generation sequencing identifies a genetic spectrum of DNA variants in patients with hemiplegic migraine

2019 ◽  
Vol 2 ◽  
pp. 251581631988163 ◽  
Author(s):  
Neven Maksemous ◽  
Robert A Smith ◽  
Heidi G Sutherland ◽  
Bridget H Maher ◽  
Omar Ibrahim ◽  
...  
Keyword(s):  
Next Generation Sequencing ◽  
Diagnostic Yield ◽  
Next Generation ◽  
Hemiplegic Migraine ◽  
Targeted Next Generation Sequencing ◽  
Variants Of Unknown Significance ◽  
High Mutation Frequency ◽  
Unknown Significance ◽  
Atp1a2 Gene ◽  
Generation Sequencing

Objective: Hemiplegic migraine in both familial (FHM) and sporadic (SHM) forms is a rare subtype of migraine with aura that can be traced to mutations in the CACNA1A, ATP1A2 and SCN1A genes. It is characterised by severe attacks of typical migraine accompanied by hemiparesis, as well as episodes of complex aura that vary significantly between individuals. Methods: Using a targeted next generation sequencing (NGS) multigene panel, we have sequenced the genomic DNA of 172 suspected hemiplegic migraine cases, in whom no mutation had previously been found by Sanger sequencing (SS) of a limited number of exons with high mutation frequency in FHM genes. Results: Genetic screening identified 29 variants, 10 of which were novel, in 35 cases in the three FHM genes ( CACNA1A, ATP1A2 and SCN1A). Interestingly, in this suspected HM cohort, the ATP1A2 gene harboured the highest number of variants with 24/35 cases (68.6%), while CACNA1A ranked the second gene, with 5 variants identified in 7/35 cases (20%). All detected variants were confirmed by SS and were absent in 100 non-migraine healthy control individuals. Assessment of variants with the American College of Medical Genetics and Genomics guidelines classified 8 variants as pathogenic, 3 as likely pathogenic and 18 as variants of unknown significance. Targeted NGS gene panel increased the diagnostic yield by fourfold over iterative SS in our diagnostics facility. Conclusion: We have identified 29 potentially causative variants in an Australian and New Zealand cohort of suspected HM cases and found that the ATP1A2 gene was the most commonly mutated gene. Our results suggest that screening using NGS multigene panels to investigate ATP1A2 alongside CACNA1A and SCN1A is a clinically useful and efficient method.

scholarly journals Diagnostic exome sequencing in non-acquired focal epilepsies highlights a major role of GATOR1 complex genes

2020 ◽  
Vol 57 (9) ◽  
pp. 624-633 ◽  
Author(s):  
Martin Krenn ◽  
Matias Wagner ◽  
Christoph Hotzy ◽  
Elisabeth Graf ◽  
Sandrina Weber ◽  
...  
Keyword(s):  
Exome Sequencing ◽  
Rare Variants ◽  
Focal Epilepsy ◽  
Diagnostic Yield ◽  
Mammalian Target Of Rapamycin ◽  
High Rate ◽  
Molecular Heterogeneity ◽  
Pathogenic Variants ◽  
Uncertain Significance

BackgroundThe genetic architecture of non-acquired focal epilepsies (NAFEs) becomes increasingly unravelled using genome-wide sequencing datasets. However, it remains to be determined how this emerging knowledge can be translated into a diagnostic setting. To bridge this gap, we assessed the diagnostic outcomes of exome sequencing (ES) in NAFE.Methods112 deeply phenotyped patients with NAFE were included in the study. Diagnostic ES was performed, followed by a screen to detect variants of uncertain significance (VUSs) in 15 well-established focal epilepsy genes. Explorative gene prioritisation was used to identify possible novel candidate aetiologies with so far limited evidence for NAFE.ResultsES identified pathogenic or likely pathogenic (ie, diagnostic) variants in 13/112 patients (12%) in the genes DEPDC5, NPRL3, GABRG2, SCN1A, PCDH19 and STX1B. Two pathogenic variants were microdeletions involving NPRL3 and PCDH19. Nine of the 13 diagnostic variants (69%) were found in genes of the GATOR1 complex, a potentially druggable target involved in the mammalian target of rapamycin (mTOR) signalling pathway. In addition, 17 VUSs in focal epilepsy genes and 6 rare variants in candidate genes (MTOR, KCNA2, RBFOX1 and SCN3A) were detected. Five patients with reported variants had double hits in different genes, suggesting a possible (oligogenic) role of multiple rare variants.ConclusionThis study underscores the molecular heterogeneity of NAFE with GATOR1 complex genes representing the by far most relevant genetic aetiology known to date. Although the diagnostic yield is lower compared with severe early-onset epilepsies, the high rate of VUSs and candidate variants suggests a further increase in future years.

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