Patients' reactions and follow-up testing decisions related to Tay-Sachs (HEXA) variants of uncertain significance results.

JScreen is a national public health initiative based out of Emory University that provides reproductive carrier screening through an online portal and follow-up genetic counseling services. In 2014, JScreen began reporting to patients variants of uncertain significance (VUSs) in the gene that causes Tay-Sachs disease (HEXA). Genetic counseling was provided to discuss the VUS and patients were offered hexosaminidase A (HEXA) blood enzyme testing to assist with VUS reclassification. To identify patient reactions and factors influencing their follow-up testing decisions after receiving these results, we conducted a retrospective quantitative study by administering online surveys to 62 patients with HEXA VUSs. Participants who pursued enzyme testing and those who did not both experienced low levels of distress when receiving the VUS results. Perceptions of HEXA carrier status after genetic counseling, decisional conflict levels, plans to have children in the near future, time available to pursue enzyme testing, and eligibility for research were significant factors influencing decision-making to pursue or not pursue enzyme testing. Genetic counseling played an important role in helping patients understand the VUS and follow-up testing options. When discussing VUSs with patients, it would be beneficial for genetic counselors to focus on the patient's perception of the VUS, anxiety related to the uncertainty of their results, and follow-up options, when available.

Screening for Tay-Sachs disease carriers by full-exon sequencing with novel variant interpretation outperforms enzyme testing in a pan-ethnic cohort.

BACKGROUND: Pathogenic variants in HEXA that impair ß-hexosaminidase A (Hex A) enzyme activity cause Tay-Sachs Disease (TSD), a severe autosomal-recessive neurodegenerative disorder. Hex A enzyme analysis demonstrates near-zero activity in patients affected with TSD and can also identify carriers, whose single functional copy of HEXA results in reduced enzyme activity relative to noncarriers. Although enzyme testing has been optimized and widely used for carrier screening in Ashkenazi Jewish (AJ) individuals, it has unproven sensitivity and specificity in a pan-ethnic population. The ability to detect HEXA variants via DNA analysis has evolved from limited targeting of a few ethnicity-specific variants to next-generation sequencing (NGS) of the entire coding region coupled with interpretation of any discovered novel variants. METHODS: We combined results of enzyme testing, retrospective computational analysis, and variant reclassification to estimate the respective clinical performance of TSD screening via enzyme analysis and NGS. We maximized NGS accuracy by reclassifying variants of uncertain significance and compared to the maximum performance of enzyme analysis estimated by calculating ethnicity-specific frequencies of variants known to yield false-positive or false-negative enzyme results (e.g., pseudodeficiency and B1 alleles). RESULTS: In both AJ and non-AJ populations, the estimated clinical sensitivity, specificity, and positive predictive value were higher by NGS than by enzyme testing. The differences were significant for all comparisons except for AJ clinical sensitivity, where NGS exceeded enzyme testing, but not significantly. CONCLUSIONS: Our results suggest that performance of an NGS-based TSD carrier screen that interrogates the entire coding region and employs novel variant interpretation exceeds that of Hex A enzyme testing, warranting a reconsideration of existing guidelines.

Direct-to-consumer personal genome testing and cancer risk prediction.

The last several years has witnessed an explosion in genomics, with the advent of genome-wide association studies revealing hundreds of DNA variants significantly associated with most common diseases, including cancer. On the heels of these scientific advances came the direct-to-consumer (DTC) genetic testing industry. Genome-wide scans for disease have been marketed and sold directly to the public, without the involvement of a health care provider. Unlike genetic testing for mutations in known hereditary cancer susceptibility genes such as BRCA1/2, these genomic profiles examine DNA variants, which typically have a minimal risk impact, and account for only a fraction of the heritable component of cancer. Furthermore, risk information provided to consumers does not account for family history or other known risk factors. The clinical validity and utility of personal genome scans for disease risk prediction remain for the most part unestablished, although some argue lack of evidence of harm and the possibility that positive impacts on health behaviors or genetic awareness may result from consumer use. The DTC genetic testing industry has sparked significant controversy not only among the scientific community, but also among professional societies and government agencies.In this review, we present some of the history and methodological considerations of DTC genomic profiling, with a focus on cancer risk prediction. The literature regarding consumer awareness and utilization is explored, including understanding, expectations, and behavioral and psychological responses to DTC genomic risk prediction. Primary care provider and genetic professional knowledge and perceptions of DTC genomic profiling are also addressed. Ethical and scientific controversy surrounding the DTC genetic testing industry is presented, along with policy recommendations, regulatory actions, and the changing landscape of the DTC genetic testing market in response. Although our understanding of the human genome holds much promise in the realm of cancer prevention and treatment, DTC genomic profiling for cancer risk prediction is unlikely in its current form to have any significant impact on the health of the public. Time will tell if the next venture in genomic medicine, whole genome sequencing, will be accompanied by the translational research and emphasis on public/provider education required to ensure its successful application toward reducing the burden of cancer at a population level.

Impact of neurofibromatosis 1 on Quality of Life: a cross-sectional study of 176 American cases.

Neurofibromatosis 1 (NF1), a genetic condition most commonly characterized by the presence of dermal neurofibromas and café au lait macules, has a significant impact on Quality of Life (QoL). There is a wide range of phenotypic variability, so that affected individuals may have either medically devastating or relatively mild manifestations that do not impact their daily lives. In this study, the SF-36 and Skindex questionnaires were used to quantitatively investigate the impact of severity and visibility on QoL in an American population. Participants were recruited primarily through advertisements distributed by The Children's Tumor Foundation (CTF). The majority participated by completing a mailed questionnaire in which they rated themselves using Ablon's visibility and Riccardi's severity scales, and then completed the SF-36 and Skindex questionnaires. Participants with NF1 reported a significant impact in all aspects of skin-disease-specific QoL, but the emotional aspect demonstrated the greatest effect. Participants with more visible signs of NF1 reported significantly greater overall effects on their skin-disease-specific QoL than those whose manifestations were more subtle. All domains of general health QoL were affected as well, especially in participants who reported having severe complications. Interestingly, greater visibility was not found to be associated with a significant decrease in general health QoL. These findings are consistent with those found in a French cohort, and demonstrate the utility of incorporating tools designed for use in both the general population and for patients with skin disease in examining the impact of NF1 on QoL.

"Are we there yet?": Deciding when one has demonstrated specific genetic causation in complex diseases and quantitative traits.

Although mathematical relationships can be proven by deductive logic, biological relationships can only be inferred from empirical observations. This is a distinct disadvantage for those of us who strive to identify the genes involved in complex diseases and quantitative traits. If causation cannot be proven, however, what does constitute sufficient evidence for causation? The philosopher Karl Popper said, "Our belief in a hypothesis can have no stronger basis than our repeated unsuccessful critical attempts to refute it." We believe that to establish causation, as scientists, we must make a serious attempt to refute our own hypotheses and to eliminate all known sources of bias before association becomes causation. In addition, we suggest that investigators must provide sufficient data and evidence of their unsuccessful efforts to find any confounding biases. In this editorial, we discuss what "causation" means in the context of complex diseases and quantitative traits, and we suggest guidelines for steps that may be taken to address possible confounders of association before polymorphisms may be called "causative."