Amy C. Sturm

How Can We Reach Them? Information Seeking and Preferences for a Cancer Family History Campaign in Underserved Communities

Individuals with a family history of cancer are at elevated risk for the disease, and web-based tools are available to assist in assessing risk. Preferences for a potential campaign to promote awareness of the role of family history in cancer risk were sought, guided by McGuires Input–Output Persuasion Model. A randomized telephone survey administered to five underserved communities assessed potential campaign messages, channels, sources, receivers, and destinations and use of the Internet (n = 101). Information sources sought about hereditary cancer and their predictors were assessed. Nearly half of the sample was African American and had annual income below

Tools for assessing readability and quality of health-related Web sites.

25,000. Most (59%) had Internet access at home. Few differences emerged as a function of race (African American vs. Other). The Internet was the most common (43%) first source sought for hereditary cancer information, followed by physicians (23%). In univariate multinomial logistic regression models, those with a high school education or more and those with greater family history (trend) were more likely than those without to choose the Internet as their first source of information over physicians. Our survey provided a wealth of information for understanding how to best launch our family history cancer risk communication campaign. Education level affected information seeking, and efforts are under way to lessen this potential barrier.

Genetic testing in cardiovascular medicine: current landscape and future horizons.

With the Internet becoming a growing source of information on genetics, genetic counselors and other health-care providers may be called upon to guide their patients to appropriate material, which is written at a suitable reading level for the individual and contains quality information. Given that many health-related Web sites are written at a high school or higher reading level, without direction from a genetic counselor or health-care provider, many Internet users may currently be turning to health-related Web sites that they do not understand. Additionally, Internet users may not know how to evaluate the quality of information they find, which could lead to them access inaccurate or irrelevant information. To aid in the process of finding and designing Web sites that are appropriate for patients, the current article provides guidelines for assessing readability and quality of health-related content. Additionally, a demonstration of an assessment is provided. Finally, limitations of these assessments are discussed.

Dysfunction in the βII Spectrin–Dependent Cytoskeleton Underlies Human Arrhythmia

Purpose of review The number of clinically available genetic tests for heritable cardiovascular diseases has recently increased because of novel gene discoveries and advancements in DNA sequencing technologies. The purpose of this review is to provide up-to-date genetic testing information and guidance on how to incorporate genetic testing into cardiovascular medicine. Recent findings Heritable cardiovascular conditions display vast genetic heterogeneity, genetic overlap between phenotypes, incomplete penetrance and variable expressivity, and are associated with risk for sudden cardiac death, making the practice of cardiovascular genetic medicine a great responsibility. Multigene testing panels now exist for many cardiovascular conditions, and test utility has recently been augmented by population-based genomic sequence datasets. Large amounts of DNA sequence data necessitate rigorous interpretation of this probabilistic information. Timely practice guidelines and expert statements have been published. Summary To fully realize the benefits of clinical genetic testing in cardiovascular medicine, clinicians must implement several components including judicious genetic testing, pretest and posttest genetic counseling, interpretation and application of genetic test results, and cascade family genetic testing and clinical screening. Components important to the proper integration of cardiovascular genetic medicine are offered.

SCN5A variant that blocks fibroblast growth factor homologous factor regulation causes human arrhythmia

Background— The cardiac cytoskeleton plays key roles in maintaining myocyte structural integrity in health and disease. In fact, human mutations in cardiac cytoskeletal elements are tightly linked to cardiac pathologies, including myopathies, aortopathies, and dystrophies. Conversely, the link between cytoskeletal protein dysfunction and cardiac electric activity is not well understood and often overlooked in the cardiac arrhythmia field. Methods and Results— Here, we uncover a new mechanism for the regulation of cardiac membrane excitability. We report that &bgr;II spectrin, an actin-associated molecule, is essential for the posttranslational targeting and localization of critical membrane proteins in heart. &bgr;II spectrin recruits ankyrin-B to the cardiac dyad, and a novel human mutation in the ankyrin-B gene disrupts the ankyrin-B/&bgr;II spectrin interaction, leading to severe human arrhythmia phenotypes. Mice lacking cardiac &bgr;II spectrin display lethal arrhythmias, aberrant electric and calcium handling phenotypes, and abnormal expression/localization of cardiac membrane proteins. Mechanistically, &bgr;II spectrin regulates the localization of cytoskeletal and plasma membrane/sarcoplasmic reticulum protein complexes, including the Na/Ca exchanger, ryanodine receptor 2, ankyrin-B, actin, and &agr;II spectrin. Finally, we observe accelerated heart failure phenotypes in &bgr;II spectrin–deficient mice. Conclusions— Our findings identify &bgr;II spectrin as critical for normal myocyte electric activity, link this molecule to human disease, and provide new insight into the mechanisms underlying cardiac myocyte biology.

Direct-to-Consumer Personal Genomic Testing: A Case Study and Practical Recommendations for “Genomic Counseling”

Significance Cardiovascular disease remains the leading cause of mortality in the United States, and cardiac arrhythmia underlies the majority of these deaths. Here, we report a new mechanism for congenital human cardiac arrhythmia due to defects in the regulation of the primary cardiac Nav channel, Nav1.5 (SCN5A), by a family of signaling molecules termed fibroblast growth factor homologous factors (FHFs). Individuals harboring SCN5A variants that affect Nav1.5/FHF interactions display atrial and ventricular phenotypes, syncope, and sudden cardiac death. The human variant results in aberrant Nav1.5 inactivation, causing prolonged action potential duration and afterdepolarizations in murine myocytes, thereby providing a rationale for the human arrhythmia. Nav channels are essential for metazoan membrane depolarization, and Nav channel dysfunction is directly linked with epilepsy, ataxia, pain, arrhythmia, myotonia, and irritable bowel syndrome. Human Nav channelopathies are primarily caused by variants that directly affect Nav channel permeability or gating. However, a new class of human Nav channelopathies has emerged based on channel variants that alter regulation by intracellular signaling or cytoskeletal proteins. Fibroblast growth factor homologous factors (FHFs) are a family of intracellular signaling proteins linked with Nav channel regulation in neurons and myocytes. However, to date, there is surprisingly little evidence linking Nav channel gene variants with FHFs and human disease. Here, we provide, to our knowledge, the first evidence that mutations in SCN5A (encodes primary cardiac Nav channel Nav1.5) that alter FHF binding result in human cardiovascular disease. We describe a five*generation kindred with a history of atrial and ventricular arrhythmias, cardiac arrest, and sudden cardiac death. Affected family members harbor a novel SCN5A variant resulting in p.H1849R. p.H1849R is localized in the central binding core on Nav1.5 for FHFs. Consistent with these data, Nav1.5 p.H1849R affected interaction with FHFs. Further, electrophysiological analysis identified Nav1.5 p.H1849R as a gain-of-function for INa by altering steady-state inactivation and slowing the rate of Nav1.5 inactivation. In line with these data and consistent with human cardiac phenotypes, myocytes expressing Nav1.5 p.H1849R displayed prolonged action potential duration and arrhythmogenic afterdepolarizations. Together, these findings identify a previously unexplored mechanism for human Nav channelopathy based on altered Nav1.5 association with FHF proteins.

Use of Whole Exome Sequencing for the Identification of Ito‐Based Arrhythmia Mechanism and Therapy

Technological advances and information-seeking consumers have pushed forward the movement of direct-to-consumer (DTC) genetic testing. Just like with other types of testing, there are potential risks, benefits and limitations. A major limitation of DTC testing is the incomplete view it provides regarding lifetime risk for common, complex diseases, since most tests only analyze 1–2 single nucleotide polymorphisms (SNPs) and do not include evaluation of medical or family histories, which is necessary to risk assessment. Further, it is not currently well-established whether personal genomic testing results will lead toward improved health behaviors, adverse psychological effects or potential overuse of the health care system. To display these and other issues, we present an in-depth case study of an individual who ordered DTC genetic testing and subsequently sought genetic counseling. This case presents a unique learning experience for the field of genomic counseling, as the patient did not fit the typical assumptions regarding ‘early adopters’ of DTC testing. It also allowed the genetics health care providers involved in the case to identify gaps in current genetic counseling practice that need to be filled and approaches to employ for successful delivery of genomic counseling. Based on our experience, we developed practical recommendations for genomic counseling, which include novel approaches to case preparation, use of electronic tools during the counseling session, and focusing on education as the major component of the genomic counseling session, in order to provide patients with the knowledge necessary to independently interpret and understand large amounts of genomic testing information provided to them.

Inherited cobalamin malabsorption. Mutations in three genes reveal functional and ethnic patterns

Background Identified genetic variants are insufficient to explain all cases of inherited arrhythmia. We tested whether the integration of whole exome sequencing with well-established clinical, translational, and basic science platforms could provide rapid and novel insight into human arrhythmia pathophysiology and disease treatment. Methods and Results We report a proband with recurrent ventricular fibrillation, resistant to standard therapeutic interventions. Using whole-exome sequencing, we identified a variant in a previously unidentified exon of the dipeptidyl aminopeptidase-like protein-6 (DPP6) gene. This variant is the first identified coding mutation in DPP6 and augments cardiac repolarizing current (Ito) causing pathological changes in Ito and action potential morphology. We designed a therapeutic regimen incorporating dalfampridine to target Ito. Dalfampridine, approved for multiple sclerosis, normalized the ECG and reduced arrhythmia burden in the proband by >90-fold. This was combined with cilostazol to accelerate the heart rate to minimize the reverse-rate dependence of augmented Ito. Conclusions We describe a novel arrhythmia mechanism and therapeutic approach to ameliorate the disease. Specifically, we identify the first coding variant of DPP6 in human ventricular fibrillation. These findings illustrate the power of genetic approaches for the elucidation and treatment of disease when carefully integrated with clinical and basic/translational research teams.

Juvenile cobalamin deficiency in individuals of African ancestry is caused by a founder mutation in the intrinsic factor gene GIF

BackgroundInherited malabsorption of cobalamin (Cbl) causes hematological and neurological abnormalities that can be fatal. Three genes have been implicated in Cbl malabsorption; yet, only about 10% of ~400-500 reported cases have been molecularly studied to date. Recessive mutations in CUBN or AMN cause Imerslund-Gräsbeck Syndrome (IGS), while recessive mutations in GIF cause Intrinsic Factor Deficiency (IFD). IGS and IFD differ in that IGS usually presents with proteinuria, which is not observed in IFD. The genetic heterogeneity and numerous differential diagnoses make clinical assessment difficult.MethodsWe present a large genetic screening study of 154 families or patients with suspected hereditary Cbl malabsorption. Patients and their families have been accrued over a period spanning >12 years. Systematic genetic testing of the three genes CUBN, AMN, and GIF was accomplished using a combination of single strand conformation polymorphism and DNA and RNA sequencing. In addition, six genes that were contenders for a role in inherited Cbl malabsorption were studied in a subset of these patients.ResultsOur results revealed population-specific mutations, mutational hotspots, and functionally distinct regions in the three causal genes. We identified mutations in 126/154 unrelated cases (82%). Fifty-three of 126 cases (42%) were mutated in CUBN, 45/126 (36%) were mutated in AMN, and 28/126 (22%) had mutations in GIF. We found 26 undescribed mutations in CUBN, 19 in AMN, and 7 in GIF for a total of 52 novel defects described herein. We excluded six other candidate genes as culprits and concluded that additional genes might be involved.ConclusionsCbl malabsorption is found worldwide and genetically complex. However, our results indicate that population-specific founder mutations are quite common. Consequently, targeted genetic testing has become feasible if ethnic ancestry is considered. These results will facilitate clinical and molecular genetic testing of Cbl malabsorption. Early diagnosis improves the lifelong care required by these patients and prevents potential neurological long-term complications. This study provides the first comprehensive overview of the genetics that underlies the inherited Cbl malabsorption phenotype.

Design and Implementation of a Randomized Controlled Trial of Genomic Counseling for Patients with Chronic Disease

In the Western World, potentially fatal megaloblastic anaemia in children is usually caused by lack of Cbl known as Juvenile Cobalamin Deficiency (JCD), which leads to hematological and neurological disturbances. The classic cause of JCD is malabsorption, the inability of the small intestine to absorb the essential molecule from dietary sources. Consensus is lacking on which laboratory tests are the best for explaining the etiology of JCD due to the myriad of potential causes (Carmel et al, 2003). Underlying mechanisms vary in different parts of the world and in different socioeconomic groups (Grasbeck 2006). However, patients may go improperly diagnosed for long periods because the serial exclusion testing for various causes can take months. Consequently, developmental delay is potentially common but easily overlooked in young children. Two main forms of inherited JCD exist: Imerslund-Grasbeck syndrome (IGS; OMIM261100; Imerslund 1960; Grasbeck et al, 1960) and Intrinsic factor Deficiency (IFD; OMIM261000; Katz et al, 1972). In IGS, deleterious mutations in either CUBN (Aminoff et al, 1999) or AMN (Tanner et al, 2003) cause malabsorption of Cbl. In IFD, mutations in the GIF gene itself are causative (Yassin et al, 2004; Tanner et al, 2005). All three genes can be sequenced in search of mutations in genomic DNA (Tanner et al, 2004, 2005). However, the screening task is daunting given that CUBN has 67 exons and AMN is very GC-rich, complicating the PCR-based analysis. To our knowledge commercial screening is not offered and research based testing is not widely available. Especially for under-served socioeconomic groups, affordable genetic testing may be years away. During our ongoing genetic studies of JCD, we have encountered four patients of West-African ancestry. Three were from the USA and one was referred to us from the UK. Sequencing of GIF revealed that all alleles with African roots carried the same c.183_186delGAAT frameshift mutation (M61fs), suggesting either a founder event or mutational recurrence. We undertook the present study to clarify this question. Genomic DNA samples were isolated from peripheral blood after informed consent by standard phenol-chloroform-ethanol-precipitation. Families 8 (Tanner et al, 2005) and 55 (Yassin et al, 2004) were described previously and are of West African decent. Family 33 is Jamaican with African ancestry living in the UK and family 39 is from the US East Coast, with the father reporting African-Native American and the mother reporting European ancestry. All four patients were given Cbl replacement therapy by parenteral Cbl injection and no longer show any clinical symptoms. Control DNA samples from 93 African-American and 93 Caucasian with no evidence of JCD were collected from the metropolitan Columbus area under a separate IRB approved protocol. For mutation analysis, we amplified GIF exon 2 from genomic DNA by PCR and analyzed it as previously described (Tanner et al, 2005). Genotyping was performed with the three microsatellite markers GIF M1 (~28 kb proximal of GIF), GIF M3b (intron 7), and GIF M4 (~2kb distal), and analyzed using fluorescent-labeled primers as described (Tanner et al, 2004). PCR conditions and primer sequences are available upon request. To elucidate if the haplotype carrying the c.183_186delGAAT mutation is an ancestral founder event, we genotyped the three flanking markers GIF M1, GIF M3b, and GIF M4 in the four families. Based on a parsimonious analysis requiring the least number of recombinations and implying linkage disequilibrium across this 40 kb region, we inferred the disease haplotype as 180-M61fs-235-168. This ancestral haplotype was found unaltered in three out of seven parents and can be explained in the remaining four by one recombination each (Fig 1). Naturally, this assumption is not taking into account the true haplotype frequencies in Africans. Thus, we studied DNA samples from 93 African-American (AA) and 93 European-American (EA) controls. After excluding the presence of the mutation in all controls, we constructed definitive haplotypes based on homozygosity and then possible haplotypes based on the observed definitive haplotypes, again using the parsimony principle. Through the resulting haplotype frequencies (Supplemental Table I), we found that none of the 93 EA control samples had the ancestral haplotype 180-235-168 on which the mutation probably arose, while only two of the 93 AA control samples carried 180-235-168 (~1%). Allele 180 of marker GIF M1 was found among 14/186 (7.5%) alleles in the AA controls, and was not detected in the EA controls (Supplemental Table I). Likewise, allele 168 of marker GIF M4 was seen in 10/186 AA alleles (5.4%) with no occurrence in EA. This allele was found in strong linkage disequilibrium with M61fs in the JCD parents with six out of seven carrying it (Fig 1). Because the ancestral haplotype 180–235-168 existed only in AA and is quite rare amongst them (~1%), we concluded that the c.183_186delGAAT mutation very likely represents a founder event for JCD patients of the Sub-Saharan West-African lineage. This mutation was never detected in ~120 cases of JCD other than these 4 cases of African ancestry. Moreover, we have not encountered any AA patient so far that had any other JCD mutation, although the numbers are still small (n=4). Fig 1 Pedigrees of four patients affected by intrinsic factor deficiency (IFD, filled symbols) due to the c.183_186delGAAT frameshift mutation (M61fs) in the intrinsic factor gene, GIF. Haplotyping with markers GIF M1, GIF M3b, and GIF M4 flanking mutation ... In summary, we identified a specific GIF mutation to be responsible for all JCD cases of West-African origin so far. The strong association of a particular mutation with a medically under-served minority could be used to their immediate benefit. It allows for quick and easy genetic testing in a disease that is notoriously difficult to diagnose but easy to treat, once the correct diagnosis is made. We believe that one simple PCR-based test in suspected cases of JCD in patients of West-African origin should be considered early during diagnosis.