Cystic fibrosis prenatal screening in genetic counseling practice: recommendations of the National Society of Genetic Counselors

Advances in the Diagnosis and Management of Cystic Fibrosis in the Genomic Era

BACKGROUND

Cystic fibrosis (CF) is a complex autosomal recessive disease that continues to present unique diagnostic challenges. Because CF was first described in 1938, there has been a substantial growth of genetic and phenotypic information about the disorder. During the past few years, as more evidence has become available, a consortium of international experts determined that the 2008 guidelines from the CF Foundation needed to be reviewed and updated.

CONTENT

The goal of this review is to highlight the latest advances in CF multidisciplinary care, together with the recent updates to the 2017 CF Foundation diagnostic guidelines.

SUMMARY

Data from newborn screening programs, patient registries, clinical databases, and functional research have led to a better understanding of the CF transmembrane conductance regulator (CFTR) gene. Recent consensus guidelines have provided recommendations for clinicians and laboratorians to better assist with interpretation of disease status and related CF mutations. The highly recommended Clinical and Functional Translation of CFTR project should be the first resource in the evaluation of disease severity for CF mutations. Screen-positive newborns and patients with high clinical suspicion for CF are always recommended to undergo confirmatory sweat chloride testing with interpretations based on updated reference intervals. Every patient diagnosed with CF should receive genotyping, as novel molecular therapies are becoming standard of practice. The future of CF management must consider healthcare system disparities as CF transitions from a historically childhood disease to a predominantly adult epidemic.

Web Platform vs In-Person Genetic Counselor for Return of Carrier Results From Exome Sequencing: A Randomized Clinical Trial

IMPORTANCE

A critical bottleneck in clinical genomics is the mismatch between large volumes of results and the availability of knowledgeable professionals to return them.

OBJECTIVE

To test whether a web-based platform is noninferior to a genetic counselor for educating patients about their carrier results from exome sequencing.

DESIGN, SETTING, AND PARTICIPANTS

A randomized noninferiority trial conducted in a longitudinal sequencing cohort at the National Institutes of Health from February 5, 2014, to December 16, 2016, was used to compare the web-based platform with a genetic counselor. Among the 571 eligible participants, 1 to 7 heterozygous variants were identified in genes that cause a phenotype that is recessively inherited. Surveys were administered after cohort enrollment, immediately following trial education, and 1 month and 6 months later to primarily healthy postreproductive participants who expressed interest in learning their carrier results. Both intention-to-treat and per-protocol analyses were applied.

INTERVENTIONS

A web-based platform that integrated education on carrier results with personal test results was designed to directly parallel disclosure education by a genetic counselor. The sessions took a mean (SD) time of 21 (10.6), and 27 (9.3) minutes, respectively.

MAIN OUTCOMES AND MEASURES

The primary outcomes and noninferiority margins (δNI) were knowledge (0 to 8, δNI = -1), test-specific distress (0 to 30, δNI = +1), and decisional conflict (15 to 75, δNI = +6).

RESULTS

After 462 participants (80.9%) provided consent and were randomized, all but 3 participants (n = 459) completed surveys following education and counseling; 398 (86.1%) completed 1-month surveys and 392 (84.8%) completed 6-month surveys. Participants were predominantly well-educated, non-Hispanic white, married parents; mean (SD) age was 63 (63.1) years and 246 (53.6%) were men. The web platform was noninferior to the genetic counselor on outcomes assessed at 1 and 6 months: knowledge (mean group difference, -0.18; lower limit of 97.5% CI, -0.63; δNI = -1), test-specific distress (median group difference, 0; upper limit of 97.5% CI, 0; δNI = +1), and decisional conflict about choosing to learn results (mean group difference, 1.18; upper limit of 97.5% CI, 2.66; δNI = +6). There were no significant differences between the genetic counselors and web-based platform detected between modes of education delivery in disclosure rates to spouses (151 vs 159; relative risk [RR], 1.04; 95% CI, 0.64-1.69; P > .99), children (103 vs 117; RR, 1.07; 95% CI, 0.85-1.36; P = .59), or siblings (91 vs 78; RR, 1.17; 95% CI, 0.94-1.46; P = .18).

CONCLUSIONS AND RELEVANCE

This trial demonstrates noninferiority of web-based return of carrier results among postreproductive, mostly healthy adults. Replication studies among younger and more diverse populations are needed to establish generalizability. Yet return of results via a web-based platform may be sufficient for subsets of test results, reserving genetic counselors for return of results with a greater health threat.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT00410241.

Presenting life with cystic fibrosis: a Q-methodological approach to developing balanced, experience-based prenatal screening information

BACKGROUND

Cystic fibrosis (CF) is one of the most common life-threatening genetically inherited conditions and prenatal screening for CF is available in many countries. Genetic counsellors and other health professionals are expected to provide information about the condition in a way that facilitates personal decision making. Knowing what information to deliver about complex genetic conditions to support informed screening decisions can be challenging for health professionals.

OBJECTIVE

To solicit views from those with personal experience with CF on which aspects of the condition they consider most important to include in prenatal screening materials.

METHODS

Q-methodology; an approach to systematically explore variations in viewpoint that combines factor analytic techniques with qualitative approaches to pattern interpretation.

SETTING AND PARTICIPANTS

Twelve adults with CF and 18 parents of affected children were recruited from a regional centre in the UK.

RESULTS

Five distinct viewpoints on the items most and least important to include in screening information were identified: Factor 1 the normality of life with CF and increasing life expectancy; Factor 2 the hardships and reduced lifespan. Factor 3 medical interventions and the importance of societal support. Factor 4 longer-term consequences of CF. Factor 5 the ability to adjust to the condition.

DISCUSSION

The identification of five different views on what represented the most and least important information to include about CF highlights the challenge of portraying a complex genetic condition in a balanced and accurate manner. Novel ways in which Q-methodology findings can be used to meet this challenge are presented.

Molecular testing for cystic fibrosis carrier status practice guidelines: recommendations of the National Society of Genetic Counselors

PURPOSE

To provide practice recommendations for genetic counselors whose clients are considering cystic fibrosis (CF) carrier testing or seeking information regarding CF molecular test results. The goals of these recommendations are to: 1) Provide updated information about the natural history, diagnosis, and treatment of CF and related conditions. 2) Supplement genetic counselors' knowledge and understanding of the available carrier screening and diagnostic testing options. 3) Describe the current state of genotype/phenotype correlations for CFTR mutations and an approach to interpreting both novel and previously described variants. 4) Provide a framework for genetic counselors to assist clients' decision-making regarding CF carrier testing, prenatal diagnosis, and pregnancy management. Disclaimer The practice guidelines of the National Society of Genetic Counselors (NSGC) are developed by members of the NSGC to assist genetic counselors and other health care providers in making decisions about appropriate management of genetic concerns; including access to and/or delivery of services. Each practice guideline focuses on a clinical or practice-based issue, and is the result of a review and analysis of current professional literature believed to be reliable. As such, information and recommendations within the NSGC practice guidelines reflect the current scientific and clinical knowledge at the time of publication, are only current as of their publication date, and are subject to change without notice as advances emerge.In addition, variations in practice, which take into account the needs of the individual patient and the resources and limitations unique to the institution or type of practice, may warrant approaches, treatments and/or procedures that differ from the recommendations outlined in this guideline. Therefore, these recommendations should not be construed as dictating an exclusive course of management, nor does the use of such recommendations guarantee a particular outcome. Genetic counseling practice guidelines are never intended to displace a health care provider's best medical judgment based on the clinical circumstances of a particular patient or patient population.Practice guidelines are published by NSGC for educational and informational purposes only, and NSGC does not "approve" or "endorse" any specific methods, practices, or sources of information.

Heterogeneity of risk within racial groups, a challenge for public health programs

Targeting high-risk populations for public health interventions is a classic tool of public health promotion programs. This practice becomes thornier when racial groups are identified as the at-risk populations. I present the particular ethical and epistemic challenges that arise when there are low-risk subpopulations within racial groups that have been identified as high-risk for a particular health concern. I focus on two examples. The black immigrant population does not have the same hypertension risk as US-born African Americans. Similarly, Finnish descendants have a far lower rate of cystic fibrosis than other Caucasians. In both cases the exceptional nature of these subpopulations has been largely ignored by the designers of important public health efforts, including the recent US government dietary recommendations. I argue that amending the publicly-disseminated risk information to acknowledge these exceptions would be desirable for several reasons. First, recognizing low-risk subpopulations would allow more efficient use of limited resources. Communicating this valuable information to the subpopulations would also promote truth-telling. Finally, presenting a more nuanced empirically-supported representation of which groups are at known risk of diseases (not focusing on mere racial categories) would combat harmful biological race essentialist views held by the public.

Mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) in Chinese patients with congenital bilateral absence of vas deferens

BACKGROUND

Genetic testing of the cystic fibrosis transmembrane conductance (CFTR) gene is currently performed in patients with congenital bilateral absence of vas deferens (CBAVD). This study was conducted to investigate the role of mutations in the CFTR gene in CBAVD-dependent male infertility.

METHODS

73 Chinese patients diagnosed with CBAVD were studied. The entire coding regions and splice sites of 27 exons of the CFTR gene were sequenced in 146 chromosomes from the 73 CBAVD patients. Screening was carried out using PCR, gel electrophoresis and DNA sequencing to identify novel variants of the entire coding regions and boundaries of the 27 exons.

RESULTS

Five novel nonsynonymous mutations, three novel splice site mutations and one deletion were identified by sequencing. Apart from the novel variants, we also found 19 previously reported mutations and polymorphism sites. Thirty-four patients (46.57%) had the 5T variant (6 homozygous and 28 heterozygous) and in two of them it was not associated with any detectable mutation of the CFTR gene. All potential pathogenic mutations are not contained in the 1000 Genome Project database. In total, the present study identified 30 potential pathogenic variations in the CFTR gene, 9 of which had not previously been described.

CONCLUSIONS

Most patients with CBAVD have mutations in the CFTR gene. A mild genotype with one or two mild or variable mutations was observed in all the patients. These findings improve our understanding of the distribution of CFTR alleles in CBAVD patients and will facilitate the development of more sensitive CFTR mutation screening.

A re-examination of the use of ethnicity in prenatal carrier testing

In April 2011, the American Congress of Obstetricians and Gynecologists (formerly the American College of Obstetrics and Gynecology [ACOG]), updated its policy on carrier screening for cystic fibrosis and proposed that because of the increasing difficulty in assigning a single ethnicity to individuals, "It is reasonable, therefore to offer CF carrier screening to all patients." However, ACOG continues to use ethnicity in its guidelines about carrier testing for autosomal recessive disorders like sickle cell disease (SCD) and Tay-Sachs disease (TSD). This practice is in marked contrast with newborn screening (NBS) which is universally provided for all conditions. In this manuscript, I evaluate the discrepant role of ethnicity in NBS and carrier screening. I argue that ACOG needs to adopt the position it now takes for CF regarding prenatal carrier testing for all conditions. To promote equity in prenatal testing decision making, health care policies must acknowledge the diversity of the populations that we serve and empower all women and couples to make more fully informed reproductive decisions by offering prenatal carrier testing to all.

Genetic counselling issues in cystic fibrosis

Cystic fibrosis is a chronic condition for which genetic testing offers much for the individuals affected in terms of an early diagnosis and offers timely additional information for families with regard to family planning and prenatal testing. Genetic counselling encompasses a range of clinical issues for families and forms a complementary resource for clinicians caring for people with cystic fibrosis. This review will discuss the range of genetic information readily available to patients and families through genetic counselling.

CYSTIC FIBROSIS – A GUIDE FOR CLINICIANS IN REPRODUCTIVE AND OBSTETRIC MEDICINE

Cystic Fibrosis (CF) is the most common life-shortening recessive genetic disease in the UK. Far from being a condition managed exclusively by paediatricians with sufferers dying in early childhood, CF is now a condition in which adults outnumber children with the condition, and the death of a child in a paediatric centre is rare. As increasing numbers of young people grow up relatively healthy it is unsurprising they begin to ask about relationships, sex, fertility and the possibility of having a child. This paper briefly describes the genetics, pathophysiology and clinical features of CF with an emphasis on how it pertains to female reproduction. The management of women with CF considering having a baby including contraception, preparation for pregnancy, the pregnancy itself, delivery and the post natal period will be discussed. Contraindications to pregnancy, method of termination, and pregnancy after transplantation will also be considered. Much of the detailed management is given in the European Guidelines for the Management of Pregnancy in Women with CF on which this paper is based.

Personal genomics services: whose genomes?

New companies offering personal whole-genome information services over the internet are dynamic and highly visible players in the personal genomics field. For fees currently ranging from US$399 to US$2500 and a vial of saliva, individuals can now purchase online access to their individual genetic information regarding susceptibility to a range of chronic diseases and phenotypic traits based on a genome-wide SNP scan. Most of the companies offering such services are based in the United States, but their clients may come from nearly anywhere in the world. Although the scientific validity, clinical utility and potential future implications of such services are being hotly debated, several ethical and regulatory questions related to direct-to-consumer (DTC) marketing strategies of genetic tests have not yet received sufficient attention. For example, how can we minimize the risk of unauthorized third parties from submitting other people's DNA for testing? Another pressing question concerns the ownership of (genotypic and phenotypic) information, as well as the unclear legal status of customers regarding their own personal information. Current legislation in the US and Europe falls short of providing clear answers to these questions. Until the regulation of personal genomics services catches up with the technology, we call upon commercial providers to self-regulate and coordinate their activities to minimize potential risks to individual privacy. We also point out some specific steps, along the trustee model, that providers of DTC personal genomics services as well as regulators and policy makers could consider for addressing some of the concerns raised below.

Twenty questions in genetic medicine--an assessment of World Wide Web databases for genetics information at the point of care

PURPOSE

The aim of this article was to determine the accuracy and efficiency of World Wide Web ("Web") resources to help nongeneticists answer four clinical questions about each of five common genetic conditions.

METHODS

Correct answers were established by literature review. Two open-access genetics resources and seven general subscription resources were reviewed. Scoring criteria were established to define complete, partial, vague, inconsistent, not found, and wrong answers. The main outcome measures were number of answers found, accuracy, and completeness of answers. Efficiency (time per answer found) was a secondary measure.

RESULTS

Overall, the databases contained complete answers 33.3% of the time but contained no information as frequently (33.9%). The best database had complete answers 70% of the time, whereas the worst contained no complete answers. Five of the seven subscription databases had a total of eight wrong answers. The other two subscription databases and the two open-access genetics databases had no wrong answers. Search time ranged from 3.2 to 18.3 minutes per complete answer.

CONCLUSIONS

Nongeneticist providers do not have a Web resource that is accessible, accurate, and efficient to answer genetic questions that might arise in practice.

XV-2c/KM19 haplotypes analysis of cystic fibrosis patients from western Mexico

The analysis of polymorphic markers within or closely linked to the cystic fibrosis transmembrane regulator (CFTR) gene is useful as a molecular tool for carrier detection of known and unknown mutations. To establish the association between mutations in the CFTR gene in western Mexican cystic fibrosis (CF) patients, the distribution of XV2c/KM19 haplotypes was analyzed by PCR and restriction enzyme digestion in 384 chromosomes from 74 CF patients, their unaffected parents, and normal subjects. The haplotype analysis revealed that haplotype B was present in 71.9% of CF chromosomes compared to 0% of non-CF chromosomes. The F508del and G542X mutations were strongly associated with haplotype B (96.7% and 100% of chromosomes, respectively). The haplotype distribution of the CF chromosomes carrying other CFTR mutations had a more heterogeneous background. Our results show that haplotype B is associated with CFTR mutations. Therefore, haplotype analysis is a suitable alternate strategy for screening CF patients with a heterogeneous clinical picture from populations with a high molecular heterogeneity where carrier detection programs are not available. In addition, it may be a helpful diagnostic tool for genetic counseling and carrier detection in the relatives of CF patients and in couples who are planning to have children.

Genetic screening in 2,710 infertile candidate couples for assisted reproductive techniques: results of application of Italian guidelines for the appropriate use of genetic tests

OBJECTIVE

To report the results of the routine application of Italian guidelines that apply to infertile patient candidates for any assisted reproduction technique (ART). The guidelines recommend performing a karyotype analysis in each couple and the screening test for mutations of the cystic fibrosis transmembrane conductance regulator (CFTR) in one of the two partners.

DESIGN

Case series.

SETTING

Infertility unit.

PATIENT(S)

Two thousand seven hundred ten consecutive infertile couple candidates for ART.

INTERVENTION(S)

Peripheral blood evaluation of karyotype and CFTR gene.

MAIN OUTCOME MEASURE(S)

Frequency of aberrant karyotype and mutated CFTR gene.

RESULT(S)

A total of 74 aberrant karyotypes were diagnosed, corresponding to 1.3% (95% confidence interval [CI], 0.9%-1.7%) in women and to 1.5% (95% CI, 1.0%-2.0%) in men. In men, the frequency of chromosomal abnormalities differed according to the treatment group (0.3%, 1.1%, and 2.2% in IUI, IVF, and ICSI, respectively). The same was not observed in women. Excluding the 5T variant, 3.8% of the screened patients showed a mutated CFTR gene (95% CI, 3.1%-4.5%), and the mutation was found in both partners in 0.2% of the couples (95% CI, 0.0-0.4%).

CONCLUSION(S)

The frequency of aberrant karyotypes is higher in infertile couples than in the general population, whereas the frequency of a mutation of the CFTR gene is similar.