Analysis of circulating tumor DNA (ctDNA) is emerging as a powerful tool for guiding targeted therapy and monitoring tumor evolution in patients with non-small cell lung cancer (NSCLC), especially when representative tissue biopsies are not available. Here, we have compared the ability of four leading technology platforms to detect epidermal growth factor receptor (EGFR) mutations (L858R, exon 19 deletion, T790M and G719X) in ctDNA from NSCLC patients. Two amplification refractory mutation systems (cobas-ARMS and ADx-ARMS), a droplet digital polymerase chain reaction (ddPCR) and a next-generation sequencing (Firefly NGS) platform were included in the comparison. Fifteen EGFR mutations across twenty NSCLC patients were identified. Firefly NGS, cobas-ARMS and ddPCR all displayed superior sensitivity while ADx-ARMS was better suited for the qualitative detection of EGFR mutations with allele frequency higher than 1% in plasma and tissue samples. We observed high coincidence between the plasma and tissue EGFR mutational profiles for three driver mutations (L858R, exon 19 deletion and G719X) that are known targets of first generation EGFR-TKI therapies among patients who relapsed. Discrepancies between tissue and plasma EGFR mutational profiles were mainly attributable to spatial and temporal tumor heterogeneity, mutation inhibition due to therapy response and drug resistance (T790M). This study illustrates the challenges associated with selection of a technology platform for EGFR ctDNA analysis in the context of treatment evaluation and drug resistance detection.

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Background Paroxysmal kinesigenic dyskinesia (PKD) is the most common type of paroxysmal dyskinesias. Only one‐third of PKD patients are attributed to proline‐rich transmembrane protein 2 (PRRT2) mutations. Objective We aimed to explore the potential causative gene for PKD. Methods A cohort of 196 PRRT2‐negative PKD probands were enrolled for whole‐exome sequencing (WES). Gene Ranking, Identification and Prediction Tool, a method of case–control analysis, was applied to identify the candidate genes. Another 325 PRRT2‐negative PKD probands were subsequently screened with Sanger sequencing. Results Transmembrane Protein 151 (TMEM151A) variants were mainly clustered in PKD patients compared with the control groups. 24 heterozygous variants were detected in 25 of 521 probands (frequency = 4.80%), including 18 missense and 6 nonsense mutations. In 29 patients with TMEM151A variants, the ratio of male to female was 2.63:1 and the mean age of onset was 12.93 ± 3.15 years. Compared with PRRT2 mutation carriers, TMEM151A‐related PKD were more common in sporadic PKD patients with pure phenotype. There was no significant difference in types of attack and treatment outcome between TMEM151A‐positive and PRRT2‐positive groups. Conclusions We consolidated mutations in TMEM151A causing PKD with the aid of case–control analysis of a large‐scale WES data, which broadens the genotypic spectrum of PKD. TMEM151A‐related PKD were more common in sporadic cases and tended to present as pure phenotype with a late onset. Extensive functional studies are needed to enhance our understanding of the pathogenesis of TMEM151A‐related PKD. © 2021 International Parkinson and Movement Disorder Society

Background: Early onset colorectal cancer (EO CRC) is a heterogeneous colorectal cancer subtype with obvious hereditary tendencies and increasing incidence. We sought to determine the susceptibility genes and molecular characteristics of EO CRC. Methods: 330 EO metastatic CRC (mCRC) (≤55 years) and 110 average-onset (AO) mCRC patients (>55 years) were enrolled. Capture-based targeted sequencing was performed on tumor tissue and paired white blood cells using a sequencing panel of 520 genes. The association between molecular alterations and overall survival (OS) was analyzed. Results: Of the 330 EO mCRC patients, 31 carried pathogenic or likely pathogenic germline mutations, with 16 of them diagnosed with lynch syndrome. Fifteen patients had germline mutations in non-mismatch repair genes, including four in MUTHY, three in RAD50, one in TP53, and eight in other genes. Twenty-nine genes were recurrently mutated in EO mCRC, including TP53, APC, KRAS, SMAD4, and BRCA2. The majority of genomic alterations were comparable between EO and AO mCRC. EO mCRC patients were more likely to have a high tumor mutation burden (p < 0.05). RNF43, RBM10, TSC, and BRAF V600E mutations were more commonly observed in EO mCRC, while APC, ASXL1, DNMT3B, and MET genes were more commonly altered in AO patients. At the pathway level, the WNT pathway was the only differentially mutated pathway between EO and AO mCRC (p < 0.0001). The wild-type WNT pathway (p = 0.0017) and mutated TGFb pathway (p = 0.023) were associated with unfavorable OS in EO mCRC. Conclusions: Approximately one in 10 EO mCRC was associated with hereditary tumors. The spectrum of somatic alterations was largely comparable between EO and AO mCRC with several notable differences.

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