Lynch syndrome (LS) predisposes patients to cancer and is caused by germline mutations in the DNA mismatch repair (MMR) genes. Identifying the deleterious mutation, such as a frameshift or nonsense mutation, is important for confirming an LS diagnosis. However, discovery of a missense variant is often inconclusive. The effects of these variants of uncertain significance (VUS) on disease pathogenesis are unclear, though understanding their impact on protein function can help determine their significance. Laboratory functional studies performed to date have been limited by their artificial nature. We report here an in‐cellulo functional assay in which we engineered site‐specific MSH2 VUS using clustered regularly interspaced short palindromic repeats‐Cas9 gene editing in human embryonic stem cells. This approach introduces the variant into the endogenous MSH2 loci, while simultaneously eliminating the wild‐type gene. We characterized the impact of the variants on cellular MMR functions including DNA damage response signaling and the repair of DNA microsatellites. We classified the MMR functional capability of eight of 10 VUS providing valuable information for determining their likelihood of being bona fide pathogenic LS variants. This human cell‐based assay system for functional testing of MMR gene VUS will facilitate the identification of high‐risk LS patients.

The standard of care in oncology has been genomic profiling of tumor tissue biopsies for the treatment and management of disease, which can prove to be quite challenging in terms of cost, invasiveness of procedure, and potential risk for the patient. As the number of available drugs in oncology continues to increase, so too does the demand for technologies and testing applications that can identify genomic alterations targetable by these new therapies. Liquid biopsies that use a blood draw from the diseased patient may offset the many disadvantages of the invasive procedure. However, as with any new technology or finding in the clinical field, the clinical utility of an analytical test such as that of the liquid biopsy has to be established. Here, we review the clinical testing space for liquid biopsy offerings and elucidate the technical and regulatory considerations to develop such an assay, using our recently validated PlasmaMonitorTM test.

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Epilepsy is one of the most common neurological disorders with about 500 genes thought to be involved across the phenotypic spectrum (Busch et al. 2014; Ran et al. 2014), which includes monogenic, multigenic, epistatic and pleiotropic phenotype manifestations (Busch et al. 2014; Thomas et al. 2014), driving the need for a comprehensive diagnostic test. Next-generation sequencing (NGS) allows for the simultaneous investigation of a large number of genes, making it a very attractive option for a condition as diverse as epilepsy at a low cost compared to traditional Sanger sequencing (Lemke et al. 2012; Németh et al. 2013). Our 377 gene epilepsy NGS test was developed to include genes known to cause or have published association with epilepsy and seizure-related disorders. Given the scale of information that is generated, the efficacy of an NGS panel depends on a number of factors, including the genes present on the panel, prebioinformatic and postbioinformatic analysis protocols, as well as reporting criteria, prompting the current study, a retrospective analysis of 305 cases tested for the epilepsy panel.

Molecular profiling of urothelial cancers for therapeutic and prognostic potential has been very limited due to the absence of cancer-specific targeted therapies. We describe here 2 clinical cases with a histological diagnosis of an invasive sarcomatoid and a poorly differentiated carcinoma favoring urothelial with some neuroendocrine differentiation, two of the rarer types of urothelial cancers, which were evaluated for mutations in 212 genes for single-nucleotide variants and copy-number variants and 53 genes for fusions associated with solid tumors. In both cases, we identified variants in 2 genes, ARID1A and CDKN2A, indicative of the role of dysregulation of chromatin remodeling and cell cycle control as being common features of bladder cancer, consistent with the proposed model of tumorigenesis in these rare, highly aggressive pathological subtypes. The presence of a KRAS mutation in the poorly differentiated cancer and a TP53 mutation in the sarcomatoid tumor is indicative of a distinctive profile and adds a potential layer of molecular stratification to these rarer histological subtypes. We present a comparative analysis of the histological, clinical, and molecular profile of both cases and discuss the potential to delineate these tumors at the molecular level keeping in mind the possible therapeutic implications.

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