Carrier Screening Program Research Articles

Experiences of a High-Risk Population with Prenatal Hemoglobinopathy Carrier Screening in a Primary Care Setting: a Qualitative Study

Carrier screening for hemoglobinopathies (HbPs; sickle cell disease and thalassemia) aims to facilitate autonomous reproductive decision-making. In the absence of a Dutch national HbP carrier screening program, some primary care midwives offer screening on an ad hoc basis. This qualitative descriptive study explores how pregnant women perceive an offer of HbP carrier screening by their midwife. Semi-structured interviews (n = 26) were conducted with pregnant women at risk of being a HbP carrier, and whom were offered screening at their booking appointment in one of two midwifery practices in Amsterdam. The results showed that half of the respondents were familiar with HbPs. Generally, women perceived the offer of HbP carrier screening as positive, and most women (n = 19) accepted screening. Seven declined, of whom two already knew their carrier status. Important reasons to accept screening were to obtain knowledge about their own carrier status and health of their unborn child, and the ease of the procedure. A multistep process of decision-making was observed, as many women did not give follow-up testing (e.g. partner, invasive diagnostics) much consideration while deciding on accepting or declining HbP screening. Women experienced information overload, and preferred receiving the information at a different moment (e.g. before the intake by a leaflet, or preconceptionally). In conclusion, while prenatal HbP carrier screening is perceived as positive, informed decision-making seems to be suboptimal, and both the content and timing of the information provided needs improvement.

P.133B - The impact of the national population carrier screening program on reducing birth rates of patients with spinal muscular atrophy

P.133B - The impact of the national population carrier screening program on reducing birth rates of patients with spinal muscular atrophy

The role of experiential knowledge within attitudes towards genetic carrier screening: A comparison of people with and without experience of spinal muscular atrophy.

PurposeAutosomal recessive conditions, while individually rare, are a significant health burden with limited treatment options. Population carrier screening has been suggested as a means of tackling them. Little is known, however, about the attitudes of the general public towards such carrier screening and still less about the views of people living with candidate genetic diseases. Here, we focus on the role that such experience has on screening attitudes by comparing views towards screening of people with and without prior experience of the monogenetic disorder, Spinal Muscular Atrophy.MethodsAn exploratory sequential mixed methods design was adopted. In‐depth qualitative interviews were used to develop two surveys. The surveys addressed attitudes towards carrier screening (pre‐conceptual and prenatal) for SMA.Participants337 participants with SMA experience completed the SMA Screening Survey (UK) and 336 participants with no prior experience of SMA completed the UK GenPop Survey, an amended version of the SMA Screening Survey (UK). ResultsThe majority of both cohorts were in favour of pre‐conception and prenatal carrier screening, however people with experience of type II SMA were least likely to support either. Key differences emerged around perceptions of SMA, with those without SMA experience taking a dimmer view of the condition than those with.ConclusionThis study underscores the significance of prior experience with the condition to screening attitudes. It highlights the need for accurate and high‐quality educational resources to support any future carrier screening programmes, that particularly in relation to rare genetic disorders like SMA that will fall outside the remit of everyday experience for the majority of the population.

Early manifestations of type 1 Gaucher disease in presymptomatic children diagnosed after parental carrier screening.

The overall published experience with pediatric type 1 Gaucher disease (GD1) has been based on ascertainment through clinical presentation of the disease. We describe the longitudinal follow-up in a presymptomatic pediatric cohort. The cohort includes children diagnosed with GD1, either prenatally or postnatally by molecular genetic testing, and followed for clinical care at our center from 1998 to 2016. All patients' parents were GBA mutation carriers identified through carrier screening programs. Longitudinal clinical, laboratory, and imaging data were obtained through chart review. Thirty-eight patients aged 1-18 years (mean at last visit 6.9 ± 4.1 years) were followed, including 32 p.N409S homozygotes and 6 p.N409S/p.R535H compound heterozygotes. At the last evaluation, a minority had hematological (5%), bone (15%), or linear growth (19%) issues. Only 12% had splenomegaly and 74% had moderate hepatomegaly. Chitotriosidase activity varied widely (6-5,640 nmol/hour/ml) and generally increased with age. Pediatric Gaucher severity scores (GSS) remained stable and within the mild-disease range for most (95%). Treatment for progressive disease during this period was recommended for four children. Most children with the p.N409S/p.N409S and p.N409S/p.R535H GD1 genotypes have minimal disease manifestations and progression during childhood and can be monitored using limited assessments. Those with other mutations may require additional monitoring. These data are valuable for newborn screening and counseling.Genet Med advance online publication 13 October 2016.

Advantages of expanded universal carrier screening: what is at stake?

Expanded universal carrier screening (EUCS) entails a twofold expansion of long-standing (preconception) carrier screening programmes: it not only allows the simultaneous screening of a large list of diseases ('expanded'), but also refers to a pan-ethnic screening offer ('universal'). Advocates mention three main moral advantages of EUCS as compared with traditional (targeted and/or ancestry-based) forms of carrier screening: EUCS will (1) maximise opportunities for autonomous reproductive choice by informing prospective parents about a much wider array of reproductive risks; (2) provide equity of access to carrier testing services; (3) reduce the risk of stigmatisation. This empirical ethics study aims to widen this account and provide a balanced picture of the potential pros and cons of EUCS. Semi-structured interviews were conducted with 17 health (policy) professionals and representatives of patient organisations about their views on carrier screening including a possible EUCS scenario. Stakeholders acknowledged the potential benefits of EUCS, but also expressed five main moral concerns: (1) Does EUCS respond to an urgent problem or population need? (2) Is it possible to offer couples both understandable and sufficient information about EUCS? (3) How will societal views on 'reproductive responsibility' change as a result of EUCS? (4) Will EUCS lead to a lower level of care for high-risk populations? (5) Will EUCS reinforce disability-based stigmatisation? While having the potential to overcome some moral limits inherent in traditional carrier screening, EUCS comes with moral challenges of its own. More research is needed to (further) anticipate the ethical and practical consequences of EUCS.

Thirteen year retrospective review of the spectrum of inborn errors of metabolism presenting in a tertiary center in Saudi Arabia.

BackgroundInborn errors of metabolism (IEMs) are individually rare; however, they are collectively common. More than 600 human diseases caused by inborn errors of metabolism are now recognized, and this number is constantly increasing as new concepts and techniques become available for identifying biochemical phenotypes. The aim of this study was to determine the type and distribution of IEMs in patients presenting to a tertiary care center in Saudi Arabia. METHOD: We conducted a retrospective review of children diagnosed with IEMs presenting to the Pediatric Department of King Abdulaziz Medical City in Riyadh, Saudi Arabia over a 13-year period.ResultsOver the 13- year period of this retrospective cohort, the total number of live births reached 110,601. A total of 187 patients were diagnosed with IEMs, representing a incidence of 169 in 100,000 births (1:591). Of these, 121 patients (64.7 %) were identified to have small molecule diseases and 66 (35.3 %) to have large molecule diseases. Organic acidemias were the most common small molecule IEMs, while lysosomal storage disorders (LSD) were the most common large molecule diseases. Sphingolipidosis were the most common LSD.ConclusionOur study confirms the previous results of the high rate of IEMs in Saudi Arabia and urges the health care strategists in the country to devise a long-term strategic plan, including an IEM national registry and a high school carrier screening program, for the prevention of such disorders. In addition, we identified 43 novel mutations that were not described previously, which will help in the molecular diagnosis of these disorders.

Prevalence of common MEFV mutations and carrier frequencies in a large cohort of Iranian populations.

Familial Mediterranean fever (FMF) is a hereditary autoinflammatory disorder caused by mutations in the MEFV gene. The disease is especially common among Armenian, Turkish, Jewish and Middle East Arab populations. To identify the frequency and the spectrum of common MEFV mutations in different Iranian populations, we investigated a cohort of 208 unselected asymptomatic individuals and 743 FMF patients. Nine hundred and fifty-one samples were analysed for the presence of 12 MEFV mutations by PCR and reverse-hybridization (FMF StripAssay, ViennaLab, Vienna, Austria). Confirmatory dideoxy sequencing of all MEFV gene exons was performed for 39 patients. Fifty-seven (27.4%) healthy individual carried mutant MEFV alleles. Three hundred and ninety-one (52.6%) FMF patients were found positive for either one (172/743; 23.1%), two or three MEFV mutations. Using dideoxy sequencing, three novel variants, A66P, R202W and H300Q, could be identified. Our analysis revealed an allele frequency and carrier rate of 15.6 and 27.4%, respectively, among healthy Iranians. Still moderate compared to neighbouring Armenia, but higher than in Turkey or Iraq, these data suggest that FMF is remarkably common among Iranian populations. E148Q was most frequent in the group of healthy individuals, whereas M694V was the most common mutation among FMF patients, thereby corroborating previous studies on MEFV mutational spectra in the Middle East. Accordingly, MEFV mutations are frequent in healthy Iranian individuals across different ethnic groups. Based on this finding, the awareness for FMF and the implementation of augmented carrier screening programmes considering the multiethnic nature of the Iranian population should be promoted.

Ethical issues in preconception genetic carrier screening

Population-based preconception genetic carrier screening programmes (PCS) with expanded panels are currently being developed in the Netherlands. This form of genetic screening for recessive traits differs from other forms of genetic testing and screening in that it is offered to persons not known to have an increased risk of being carriers of genetic traits for severe recessive diseases and in that they include tests for a large number of traits, potentially several hundred. This raises several ethical issues around justice, consequences, and autonomy. It will be argued that most of these ethical problems call for cautious reflection when setting up PCS and similar programmes within preconception care. It is moreover argued that it is ethically problematic to have an official aim and failing to mention possibly legitimate public aims that actually drive the development of PCS.

Expanding preconception carrier screening for the Jewish population using high throughput microfluidics technology and next generation sequencing.

BackgroundGenetic screening to identify carriers of autosomal recessive diseases has become an integral part of routine prenatal care. In spite of the rapid growth of known mutations, most current screening programs include only a small subset of these mutations, and are performed using diverse molecular techniques, which are generally labor-intensive and time consuming. We examine the implementation of the combined high-throughput technologies of specific target amplification and next generation sequencing (NGS), for expanding the carrier screening program in the Israeli Jewish population as a test case.MethodsWe compiled a panel of 370 germline mutations, causing 120 disorders, previously identified in affected Jewish individuals from different ethnicities. This mutation panel was simultaneously captured in 48 samples using a multiplex PCR-based microfluidics approach followed by NGS, thereby performing 17,760 individual assays in a single experiment.ResultsThe sensitivity (measured with depth of at least 50×) and specificity of the target capture was 98 and 95 % respectively, leaving minimal rate of inconclusive tests per sample tested. 97 % of the targeted mutations present in the samples were correctly identified and validated.ConclusionOur methodology was shown to successfully combine multiplexing of target specific primers, samples indexing and NGS technology for population genetic screens. Moreover, it’s relatively ease of use and flexibility of updating the targets screened, makes it highly suitable for clinical implementation. This protocol was demonstrated in pre-conceptional screening for pan-Jewish individuals, but can be applied to any other population or different sets of mutations.Electronic supplementary materialThe online version of this article (doi:10.1186/s12920-016-0184-7) contains supplementary material, which is available to authorized users.

"It gives them more options": preferences for preconception genetic carrier screening for fragile X syndrome in primary healthcare.

This study aims to explore stakeholder views about offering population-based genetic carrier screening for fragile X syndrome. A qualitative study using interviews and focus groups with stakeholders was undertaken to allow for an in-depth exploration of views and perceptions about practicalities of, and strategies for, offering carrier screening for fragile X syndrome to the general population in healthcare settings. A total of 188 stakeholders took part including healthcare providers (n = 81), relatives of people with fragile X syndrome (n = 29), and members of the general community (n = 78). The importance of raising community awareness about screening and providing appropriate support for carriers was emphasized. There was a preference for preconception carrier screening and for providing people with the opportunity to make an informed decision about screening. Primary care was highlighted as a setting which would ensure screening is accessible; however, challenges of offering screening in primary care were identified including time to discuss screening, knowledge about the test and possible outcomes, and the health professionals' approach to offering screening. With the increasing availability of genetic carrier tests, it is essential that research now focuses on evaluating approaches for the delivery of carrier screening programs. Primary healthcare is perceived as an appropriate setting through which to access the target population, and raising awareness is essential to making genetic screening more accessible to the general community.

The impact of a national population carrier screening program on cystic fibrosis birth rate and age at diagnosis: Implications for newborn screening

BackgroundPopulation carrier screening (PCS) has been available in Israel since 1999 and universally subsidized since 2008. We sought to evaluate its impact. MethodsA retrospective review of governmental databanks, the national CF registry and CF centers. ResultsCF rate per 100,000 live births has decreased from 14.5 in 1990 to 6 in 2011. From 2004–2011 there were 95 CF births: 22 utilized PCS; 68 (72%) had 2 known CFTR mutations; 37% were pancreatic sufficient. At diagnosis, age was 6 (0–98) months; 53/95 had respiratory symptoms, 41/95 failure to thrive and 19/95 pseudomonas. Thirty-four (36%) were Arabs and 19 (20%) orthodox Jews, compared to 20% and 8% respectively, in the general population. ConclusionsPCS markedly reduced CF birth rates with a shift towards milder mutations, but was often avoided for cultural reasons. As children regularly have significant disease at diagnosis, we suggest a balanced approach, utilizing both PCS and newborn screening.

AB157. Evaluation of thalassemia screening program by using red blood count in pregnant women at Hung Vuong Hospital, Ho Chi Minh City, Vietnam.

Background To evaluate thalassemia carrier screening program using red blood count indices (RBC) at Hung Vuong hospital, Ho Chi Minh City, Viet Nam, from June 2010 to March 2013.

Expanded genetic screening panel for the Ashkenazi Jewish population.

Carrier screening programs that identify the presence of known mutations have been effective for reducing the incidence of autosomal recessive conditions in the Ashkenazi Jewish (AJ) population and other populations. Yet, these programs have not realized their full potential. Furthermore, many known autosomal recessive and dominant conditions are not screened for and the molecular basis of other conditions for which screening might be offered is unknown. Through literature review and annotation of full sequenced genomes from healthy individuals, we expanded the list of mutations. Mutations were identified in a sample of 128 fully sequenced AJ genomes that were filtered through clinical databases and curated manually for clinical validity and utility using the American College of Medical Genetics and Genomics scoring (ACMG) system. Other known mutations were identified through literature review. A panel of 163 mutations was identified for 76 autosomal recessive, 24 autosomal dominant, and 3 X-linked disorders. Screening for a broader range of disorders not only could further reduce the incidence of autosomal recessive disorders but also could offer the benefits of early or presymptomatic diagnosis.Genet Med 18 5, 522-528.

Attitudes of cystic fibrosis patients and parents toward carrier screening and related reproductive issues.

Cystic fibrosis (CF) is a life-limiting autosomal recessive disorder affecting ~1 in 2500-4000 Caucasians. As most CF patients have no family history of the disorder, carrier screening for CF has the potential to prospectively identify couples at risk of conceiving an affected child. At-risk couples may consequently choose to act on the provided information and take steps to avoid the birth of a child with CF. Although carrier screening is widely believed to enhance reproductive autonomy of prospective parents, the practice also raises important ethical questions. A written questionnaire was administered to adult patients and parents of children with CF with the aim to explore participants' attitudes toward CF carrier screening and related reproductive issues. The study population was recruited from a CF patient registry in Belgium and comprised 111 participants (64 parents, 47 patients aged 16 or older). We found that more than 80% of all participants were in favor of preconception carrier screening for CF. However, some were concerned over potential negative consequences of population-wide CF carrier screening. Regarding future reproductive intentions, 43% of the participants indicated a desire to have children. Among these, preimplantation genetic diagnosis was found to be the most preferred reproductive option, closely followed by spontaneous pregnancy and prenatal diagnosis. Although the findings of our study suggest that patients and parents of children with CF support a population-based carrier screening program for CF, they also highlight some issues deserving particular attention when implementing such a program.

State-offered ethnically targeted reproductive genetic testing.

report on a program that involves state-offered carrier screening for cystic fibrosis, spinal mus-cular atrophy, and fragile X for the entire population of Israel, with screening for a wide array of additional diseases selected based on a combination of ethnicity, religious affiliation, and locality of origin. To their credit, Zlotogora et al.

"Suddenly Having two Positive People who are Carriers is a Whole New Thing" - Experiences of Couples Both Identified as Carriers of Cystic Fibrosis Through a Population-Based Carrier Screening Program in Australia.

A population-based CF carrier screening program was implemented in Victoria, Australia in 2006. This study explored the experiences of couples when both partners were identified as CF carriers. Between January 2006 and December 2010, 10 carrier couples were identified and invited to undertake a semi-structured interview. Nine interviews were conducted, seven couple interviews and two individual interviews. One couple declined to participate due to the recent termination of an affected pregnancy. Interviews were analyzed using inductive content analysis. All couples experienced surprise on learning their carrier couple result. The couples who were pregnant at the time of screening chose to have prenatal diagnosis, with the majority considering it to be the "next step." The two couples who had an affected pregnancy reported feelings of devastation and grief upon receiving their prenatal diagnosis result and terminated the pregnancy. All carrier couples were offered free genetic counseling, with only one couple declining the offer. Couples were unprepared for a positive carrier couple result. However, all the couples changed their reproductive behavior as a result of their carrier status. The results of this study have been used to inform the program and service offered to CF carrier couples particularly with respect to genetic counseling for reproductive decision making.

The Israeli national population program of genetic carrier screening for reproductive purposes

The Israeli population genetic screening program for reproductive purposes, launched in January 2013, includes all known, nationally frequent severe diseases (carrier frequency 1:60 and/or disease frequency 1 in 15,000 live births). The carrier screening program is free of charge and offers testing for cystic fibrosis, fragile X syndrome, and spinal muscular atrophy for nearly the entire population, according to disease frequency among the different groups within the population. We report the results of the first year of the program. Data on the tests performed over a 12-month period were collected from laboratories nationwide. More than 62,000 individuals were examined. The carrier frequency was within the expected range for most of the diseases. The few exceptions included lower carrier rates for cystic fibrosis among Muslim Arabs (1:236) and Druze (1:1,021) and Niemann-Pick type A among Muslim Arabs in a delineated region of Israel (1:229). The national population genetic carrier screening is aimed toward providing couples with knowledge of the existing options for the prevention of serious genetic conditions when it is relevant for them. It is still too early to determine whether this aim has been achieved.

Thalassaemia control in developing countries--the Sri Lankan perspective.

Beta thalassaemia is a Mendelian recessive disorder. The economic and social cost of the disease is high due to patients' life long need for monthly blood transfusions and treatment with desferrioxamine, an iron chelating agent. Wider availability of cheaper drugs is on the horizon. If there is no concomitant reduction in the number of new thalassaemia major births, there will be a cumulative increase in numbers requiring treatment. The frequency and severity, and the economic and social costs of thalassaemia, support the case for the introduction of a carrier screening and counselling program in Sri Lanka. A three-pronged plan emphasising professional, political and public education in outlined.

Knowledge, attitudes, and barriers to carrier screening for the Ashkenazi Jewish panel: a Florida experience

The knowledge, attitudes, and barriers to Jewish genetic diseases (JGDs) and screening and their relative importance in reproductive decision-making were assessed in a population-based sample of Ashkenazi Jewish young adults in Florida. These adults attended educational screening fairs hosted by The Victor Center for the Prevention of Jewish Genetic Diseases at the University of Miami. Parametric and nonparametric tests were used as appropriate to analyze data from a single group pretest/posttest design. Four hundred twelve individuals (mean age = 24.9; 54.7% female, 45.3% male) completed the questionnaires. Participants' level of knowledge increased from pre- to post-intervention (81.4 vs. 91.0%; p < 0.0001). Concern about the possibility of being a carrier of a JGD was significantly higher after an educational session (5-point Likert scale mean difference = 0.45; p < 0.0001), as was their level of concern regarding having an affected child (mean difference = 0.20; p < 0.0001). The number of participants who agreed or strongly agreed that the test results would not have any influence on their reproductive behavior was lower after the session (17.2 vs. 20.8%; p < 0.0001). This study demonstrates that an educational carrier screening program increased knowledge and elucidated awareness of the attitudes and barriers toward JGDs and carrier screening.

Community genetics approaches in the prevention of beta-thalassemia: towards achieving 'Zero beta-thalassemia' status in India.

The estimates of prevalence of b-thalassemia in India are grossly underestimated, as it is based on 0-5% carrier frequency, while population surveys indicated communities with as high frequency as 24%. The overall carrier frequency distribution of b-thalassemia, is highly heterogeneous with wide geographical foci of high risk communities with 8% and above carrier frequency all over the country. As of now, there is no mechanism to evaluate whether the frequencies are increasing or decreasing in the populations. Prenatal diagnosis and prevention of births of b-thalassemia homozygotes is the most preferred approach adopted in India. However, the extent of distribution and the occurrence across various stratification in the society with large component of rural masses, it is difficult to assume that prenatal diagnosis alone can bring in ‘Zero’ b-thalassemia status in India. Countries like Cyprus could achieve such status where large scale population carrier screening programs involving education and premarital counselling were also effectively employed besides prenatal diagnosis. In India, there is urgent need to initiate large scale population carrier screening of high risk communities along with education and awareness. The extent of b-thalassemia distribution, identifying high risk communities and geographical regions presenting a population design for carrier screening program in India, will be presented.