Katrina E. Kotzer

Increased frequency of FBN1 truncating and splicing variants in Marfan syndrome patients with aortic events

Purpose:Marfan syndrome is a systemic disorder that typically involves FBN1 mutations and cardiovascular manifestations. We investigated FBN1 genotype–phenotype correlations with aortic events (aortic dissection and prophylactic aortic surgery) in patients with Marfan syndrome.Methods:Genotype and phenotype information from probands (n = 179) with an FBN1 pathogenic or likely pathogenic variant were assessed.Results:A higher frequency of truncating or splicing FBN1 variants was observed in Ghent criteria–positive patients with an aortic event (n = 34) as compared with all other probands (n = 145) without a reported aortic event (79 vs. 39%; P < 0.0001), as well as Ghent criteria–positive probands (n = 54) without an aortic event (79 vs. 48%; P = 0.0039). Most probands with an early aortic event had a truncating or splicing variant (100% (n = 12) and 95% (n = 21) of patients younger than 30 and 40 years old, respectively). Aortic events occurred at a younger median age in patients with truncating/splicing variants (29 years) as compared with those with missense variants (51 years). A trend toward a higher frequency of truncating/splicing variants in patients with aortic dissection (n = 21) versus prophylactic surgery (n = 13) (85.7 vs. 69.3%; not significant) was observed.Conclusion:These aortic event– and age-associated findings may have important implications for the management of Marfan syndrome patients with FBN1 truncating and splicing variants.Genet Med 17 3, 177–187.

Looking Back and Moving Forward: An Historical Perspective from Laboratory Genetic Counselors

Despite a consistent increase in genetic counselors who report working in laboratory positions, there is a relative dearth of literature on laboratory genetic counseling. Semi-structured interviews were completed with nine laboratory genetic counselors to document how positions were created and have changed with time. Interview transcriptions were analyzed for emerging themes. Several common themes were identified, including that early positions were often part-time, laboratory-initiated and had a lack of job definition. Laboratory genetic counselors commented on their evolving roles and responsibilities, with their positions becoming more technical and specialized over time and many taking on managerial and supervisory roles. All genetic counselors surveyed reported using core genetic counseling skills in their positions. The expansion of diagnostic testing and quickly evolving technology were common themes in regards to the future of laboratory genetic counselors, and participants commented on laboratory genetic counselors having expanding roles with data management, result interpretation and reporting, and guidance of other healthcare providers. Other comments included the impact of competition among laboratories and how training programs can better prepare genetic counseling students for a career in the laboratory setting. This study describes the emergence, and subsequent evolution, of laboratory genetic counseling positions as a significant subspecialty of genetic counseling.

Genetic testing utilization and the role of the laboratory genetic counselor.

Laboratory genetic counselors within hospital laboratories and genetic testing laboratories have an important role in increasing the appropriate utilization of genetic tests. This service is becoming more important as genetic testing becomes more complex and the demand for genetic testing in healthcare increases. Additionally genetic tests are among the most expensive assays in the clinical laboratory test catalog. Laboratory genetic counselors are able to increase genetic test utilization through review and assessment of the appropriateness of the ordered testing, developing protocols, and by increasing communication with ordering providers.

The Genetic Counselor’s Role in Managing Ethical Dilemmas Arising in the Laboratory Setting

Ethical dilemmas are encountered commonly in the setting of the clinical genetic testing laboratory due to the complexity of genetic testing and the number of relevant stakeholders involved in the genetic testing process. Based on their clinical training and role within the laboratory, genetic counselors are uniquely equipped to identify and facilitate management of ethical dilemmas. This paper reviews the historical context of ethical theory and its application to the field of genetic counseling. Theoretical and applied ethics are explored in the context of dilemmas arising in the laboratory setting, with a focus on the role of the laboratory genetic counselor in managing ethical dilemmas. Two illustrative case examples are provided.

A Case for Inclusion of Genetic Counselors in Cardiac Care.

Recent advances in genetic testing for heritable cardiac diseases have led to an increasing involvement of the genetic counselor in cardiology practice. We present a series of cases collected from a nationwide query of genetics professionals regarding issues related to cost and utilization of genetic testing. Three themes emerged across cases: (1) choosing the most appropriate genetic test, (2) choosing the best person to test, and (3) interpreting results accurately. These cases demonstrate that involvement of a genetic counselor throughout the evaluation, diagnosis, and continuing management of individuals and families with inherited cardiovascular conditions helps to promote the efficient use of healthcare dollars.

Decreased frequency of FBN1 missense variants in Ghent criteria-positive Marfan syndrome and characterization of novel FBN1 variants

The diagnosis of Marfan syndrome (MFS) remains challenging despite the 2010 revision to Ghent nosology criteria, and there is a lack of published information regarding FBN1 genotype associations in patients since the update in Ghent criteria. Applying revised Ghent criteria, we reviewed consecutive proband cases (n=292) submitted for FBN1 sequencing. Testing yielded 207 pathogenic or likely pathogenic FBN1 variants, with 114/207 (55%) missense, 67/207 (32%) non-sense or frameshift, and 28/207 (13%) splicing. There were 130 novel FBN1 variants predicted as pathogenic or likely pathogenic (n=109) or variant of undetermined significance (n=21). Of the 104 patients who met 2010 revised Ghent criteria, 87/104 (82%) had a pathogenic or likely pathogenic variant. There was a significantly lower frequency of missense variants (41 vs 89%; P<0.0001) observed in the Ghent-positive (vs Ghent-negative) patients, and this association held true in age-based groupings. Previously described genotype associations with ectopia lentis and early onset/‘neonatal’ MFS were confirmed in our cohort. Overall, our study points to the imperfect nature of relying solely on clinical criteria to diagnose MFS as well as the potential importance of truncating/splicing variants in Ghent-positive cases. Furthermore, the description of numerous novel variants and associated clinical findings may be useful for future clinical interpretation of FBN1 genotype in patients with suspected MFS.

Genetic and biochemical analyses in dyslipidemic patients undergoing LDL apheresis

Objective: Familial hypercholesterolemia (FH) can be due to mutations in LDLR, PCSK9, and APOB. In phenotypically defined patients, a subset remains unresponsive to lipid‐lowering therapies and requires low density‐lipoprotein (LDL) apheresis treatment. In this pilot study, we examined the genotype/phenotype relationship in patients with dyslipidemia undergoing routine LDL apheresis. Design: LDLR, APOB, and PCKS9 were analyzed for disease‐causing mutations in seven patients undergoing routine LDL apheresis. Plasma and serum specimens were collected pre‐ and post‐apheresis and analyzed for lipid concentrations, Lp(a) cholesterol, and lipoprotein particle concentrations (via NMR). Results: We found that four patients harbored LDLR mutations and of these, three presented with xanthomas. While similar reductions in LDL‐cholesterol (LDL‐C), apolipoprotein B, and LDL particles (LDL‐P) were observed following apheresis in all patients, lipid profile analysis revealed the LDLR mutation‐positive cohort had a more pro‐atherogenic profile (higher LDL‐C, apolipoprotein B, LDL‐P, and small LDL‐P) pre‐apheresis. Conclusion: Our data show that not all clinically diagnosed FH patients who require routine apheresis have genetically defined disease. In our small cohort, those with LDLR mutations had a more proatherogenic phenotype than those without identifiable mutations. This pilot cohort suggests that patients receiving the maximum lipid lowering therapy could be further stratified, based on genetic make‐up, to optimize treatment. J. Clin. Apheresis 29:256–265, 2014.

Technical Advances for the Clinical Genomic Evaluation of Sudden Cardiac Death: Verification of Next-Generation Sequencing Panels for Hereditary Cardiovascular Conditions Using Formalin-Fixed Paraffin-Embedded Tissues and Dried Blood Spots

Background— Postmortem genetic testing for heritable cardiovascular (CV) disorders is often lacking because ideal specimens (ie, whole blood) are not retained routinely at autopsy. Formalin-fixed paraffin-embedded tissue (FFPET) is ubiquitously collected at autopsy, but DNA quality hampers its use with traditional sequencing methods. Targeted next-generation sequencing may offer the ability to circumvent such limitations, but a method has not been previously described. The primary aim of this study was to develop and evaluate the use of FFPET for heritable CV disorders via next-generation sequencing. Methods and Results— Nineteen FFPET (heart) and blood (whole blood or dried blood spot) specimens underwent targeted next-generation sequencing using a custom panel of 101 CV-associated genes. Nucleic acid yield and quality metrics were evaluated in relation to FFPET specimen age (6 months to 15 years; n=14) and specimen type (FFPET versus whole blood and dried blood spot; n=12). Four FFPET cases with a clinical phenotype of heritable CV disorder were analyzed. Accuracy and precision were 100% concordant between all sample types, with read depths >100× for most regions tested. Lower read depth, as low as 40×, was occasionally observed with FFPET and dried blood spot. High-quality DNA was obtained from FFPET samples as old as 15 years. Genomic analysis of FFPET from the 4 phenotype-positive/genotype unknown cases all revealed putative disease-causing variants. Conclusions— Similar performance characteristics were observed for next-generation sequencing of FFPET, whole blood, and dried blood spot in the evaluation of inherited CV disorders. Although blood is preferable for genetic analyses, this study offers an alternative when only FFPET is available.