Background Preconception carrier screening (PCS) provides the potential to empower couples to make reproductive choices before having an affected child. An important question is what factors influence the decision to use or not use PCS.
Methods We analysed the relationship between knowledge, attitudes and intentions to participate in PCS using logistic regression in 832 participants in Western Australia.
Results Two-thirds of participants said they would take the test, with 92% of these supporting screening for diseases reducing the lifespan of children and infants. Those who had good genetic knowledge were seven times more likely to intend to use PCS (p≤0.001), while those with high genetic knowledge were four times more likely to (p=0.002) and raised concerns such as insurance and confidentiality.
Decreasing genetic knowledge correlated positively with religiosity and apprehension (p≤0.001), which correlated negatively with intention to use PCS (p≤0.001). Increasing genetic knowledge correlated positively with factors representing positive attitudes (p≤0.001), which correlated positively with intention to use PCS (p≤0.001). Many participants with good genetic knowledge nevertheless answered questions that tested understanding incorrectly.
80% of participants stated they would prefer to access the test through their general practitioners and 30% would pay up to $A200.
Conclusions Knowledge is instrumental in influencing participation. Having good genetic knowledge may not be enough to understand core concepts of PCS and may impact informed decision-making. This study recommends that continuous education of health professionals and thus the community, in PCS is crucial to reduce misconceptions.
- genetic screening/counselling
- getting research into practice
- reproductive medicine
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Autosomal recessive diseases are genetic diseases that arise when both parents in a couple are carriers of the same recessive disease. In this situation, the couple have a 1-in-4 risk of an affected child in each pregnancy. Since carriers of recessive diseases are usually unaffected, children with recessive diseases are most often born into families with no history of the disease.1 The risk of having a child with these severe recessive diseases is higher than2 or equal1 to the birth prevalence of children with Down syndrome.3 Genetic disease is responsible for a significant proportion of infant morbidity and mortality4 and the burden of genetic disease on patients, families and society in terms of suffering and cost is large. For example, Walker et al investigated 437 rare diseases defined by orpha codes and demonstrated that these diseases affected 2% of the population in Western Australia; however, accounted for 9.9% of hospitalisations and 10.5% of hospitalisation costs, at AUD 395m a year.5
Preconception carrier screening (PCS) aims, according to the European Society of Human Genetics Public and Professional Policy Committee, ’to facilitate informed reproductive decision making by identifying those couples at risk of having an affected child with an (autosomal or X linked) recessive disorder’.6 PCS programmes have historically been for severe recessive diseases in high-risk populations, such as Tay-Sachs disease (TSD (OMIM #272800)) in the Ashkenazi-Jewish community,7 or thalassaemia in Mediterranean countries.8 These programmes reduced the birth prevalence of TSD by over 90%7 in the Ashkenazi community and of thalassaemia, in Sardinia, for example, from 1:250 to 1:4000.8 However, recommendations have been in place for some time for carrier screening of selected recessive genetic diseases in the general population. For example, the American College of Medical Genetics recommended carrier screening for cystic fibrosis (CF (MIM 219700)) to all couples regardless of ethnicity in 20019 and for spinal muscular atrophy (SMA (MIM 253300)) in 2008.10
It has been deduced and now shown experimentally that everyone is a carrier of two to eight severe recessive lethal mutations.11 12 Therefore, screening for multiple recessive diseases through expanded carrier screening has the potential to identify more couples at risk of an affected pregnancy.13 Haque et al in 2016 modelled an expanded panel of around 100 genes covering multiple recessive diseases and demonstrated it could detect carrier status for many more severe conditions than screening based on the guidelines then in place.14
In 2017, the American College of Obstetricians and Gynecologists recommended that all patients should be offered PCS, according to their values, including expanded carrier screening for multiple genetic disorders.15 Currently, Israel performs one of the most comprehensive pan-ethnic population-wide PCS programmes, screening >60 000 citizens annually for an expanded list of diseases.16
In Western Australia, the largest ethnic population, at 62%, is of European descent, with therefore the same carrier risks as other European countries. There is however an increasing proportion of individuals of African, Asian and Middle Eastern descent with higher frequencies of some recessive diseases such as thalassaemia and higher rates of consanguinity than in the general population. This demography is similar to the rest of Australia.17 There is no population-based PCS programme available in Western Australia currently, the only screening available through the public health system is cascade screening in families of individuals affected by a genetic disease. Screening from commercial entities is available but not subsidised by the healthcare system.18 Reproductive options available to at-risk Australian couples include using assisted reproductive technologies such as in vitro fertilisation (IVF) with preimplantation diagnostic genetic diagnosis.19 However, the cost per IVF cycle in Australia is complex with partial subsidy from Medicare and some private health insurance cover, resulting in considerable out-of-pocket expenses.20 Prenatal diagnosis is also available for at-risk couples and is fully subsidised by Medicare. Other options for at-risk couples include adoption, foregoing having children or not intervening in pregnancies.21
Increasing interest in providing PCS to the general population has led to multiple investigations into various aspects of carrier screening such as the opinions of target patient groups in various countries,2 22–24 or to the use of publicly available databases such as The Exome Aggregation Consortium (ExAC)25 and 1000 Genomes26 to retrospectively determine carrier frequencies of diseases of interest.14 27 28 However, previous studies have shown that the public’s willingness to use PCS is limited. Attitudes towards PCS are multifaceted and influenced by a range of factors including lack of knowledge, feelings of vulnerability and concerns regarding the impact of the test.2 22 23 28 These international studies explored various factors such as preferences, familiarity and perceived benefits or risk. Previous research in Australia has included obstetricians29 or qualitatively explored themes surrounding carrier screening.30
Since knowledge is known to be an important factor influencing a person’s intention to participate in a PCS programme,31 32 we sought to explore baseline levels of genetic knowledge and awareness regarding PCS in Western Australia prior to the implementation of any public health information campaigns without specifying what PCS meant in the survey. We also aimed to investigate factors that might influence knowledge and attitudes to participation in any future PCS programme implemented in Western Australia.
Study design and participant recruitment
The study was a cross-sectional study of 832 adults who participated in an online survey conducted by a third-party market research company over a 2-week period in March 2017. Eligibility criteria were residing in Western Australia and being aged 18 years or older. The survey took approximately 15 min to complete. A total of 24 530 individuals on four online panels of Western Australian residents were invited to participate through emails from the market research company.
As we wished to measure current baseline knowledge and attitudes towards PCS of the Western Australian community, no information on PCS was provided to the participants.
The questionnaire contained several existing scales measuring prior knowledge of PCS, genetic knowledge, attitudes towards PCS, intention to take a PCS test and follow-up considerations of PCS. Established scales included in this questionnaire were modified for this study to be specific to rare diseases. For example, the question ‘Will lead to discrimination of people with CF’33 was modified to ‘Will lead to discrimination of people with rare diseases’.
Genetic knowledge and prior knowledge of PCS
Questions about genetic knowledge were obtained from three studies.34–36 A total of 21 questions were used to test participants’ level of genetic knowledge such as ‘Unaffected parents can have a child with an inherited disease ’ and ‘ A gene is part of a chromosome’ (table 1 and online supplementary table S1). Participants’ responses to the genetic questions were consistent, with an alpha score of 0.89. A Pearson’s product-moment correlation was run to determine validity of the genetic questions tested. There was a strong positive correlation between all questions, which was statistically significant (p≤0.001). Individual results were stratified into IQRs based on the total number of correctly answered genetic questions: high, good, some and low.
Attitudes towards PCS
Items such as ‘Should be made available for all couples planning a pregnancy’ and "I will be discriminated against if I am identified as a carrier" measured participants’ attitudes towards PCS and were obtained and modified from existing scales33 35 and measured on a six-point Likert scale (1=strongly disagree; 3=neither agree nor disagree; 5=strongly agree and 6=do not know or not applicable).
Principal factor analysis with varimax rotation, with an Eigenvalue >1.0 was used to identify possible underlying dimensions in the individual statements measuring attitudes. Values <0.4 were suppressed and not displayed. Reliability analysis was also used to determine the homogeneity of each set of statements (Cronbach’s α). To investigate how each factor was associated with intention to take the PCS test and genetic knowledge, statements from each item in each factor were combined to create a mean score. All items in each factor were measured on the same scale. The 22 items used to measure various aspects of attitudes loaded onto four factors and explained 61% of the total variance in those items. Factor 1 to factor 4 explained 33.7%, 16.4%, 6.1% and 4.8% of the variance, respectively (see online supplementary table S2). Each factor was labelled to best reflect the items grouped in that factor and the main construct/s it was measuring. Factor 1 included 11 items measuring apprehension and religious beliefs (α=0.899). Factor 2 included five items measuring equity of access and feelings of empathy (α=0.848). Factor 3 included three items that measured feelings about individuals with a genetic disorder (α=0.848). Factor 4 consisted of three items measuring test-related concerns (α=0.784). All four factors were included in the overall model (see online supplementary table S2).
Intention to take a PCS test
Intention to take a PCS test was measured using the existing item2 "If you are offered preconception carrier screening, would you accept the test?" on a three-point Likert scale (1=yes; 2=no and 3=unsure).
Follow-up considerations of PCS
Existing items such as "I will do the test if the diseases detected are very severe" and "I will do a preconception carrier-screening test if it costs me less than $50", which measured preferences on the way the PCS test is offered,2 were included and were measured on a dichotomous scale (yes/no).
Sociodemographic and other potential confounders were included in the online survey and comprised age, gender, location of residence, education level, religiosity or spirituality, individual annual income, relationship status, parenthood experience and intention to be parents (see online supplementary table S3 and S4).
Descriptive analysis was run to understand participants’ characteristics. Chi-square tests of independence were used to examine the association between intention to take a PCS test and i) sociodemographic and other potential confounders; ii) prior knowledge about the screening programme and iii) genetic knowledge.
Multinomial logistic regression and ordinal logistic regression were used to identify factors associated with intention to take a PCS test and genetic knowledge and attitudes towards PCS. Sociodemographic variables that were significantly associated with intention to take the test were included in each logistic regression analysis.
A total of 832 participants completed the survey and 84.5% (n=719) were of reproductive age (defined as 18–44 years of age). There were approximately the same proportion of males and females. More than 36% had completed a university degree. At least 42% of participants had an annual income less than the Western Australian median income of $A52 504 per annum37; indicating that in regard to income, the respondents were a good representation of the Western Australian population. Almost half of the responders were not religious. Most participants (71.3%) were in a relationship, 49.9% were parents and 70.6% of participants reported their intention to become parents (table 2).
Intention to take a PCS test and follow-up considerations
Accepting the test
Overall, 67.5% (n=562) of participants indicated that they would take the test if PCS was offered to them (table 2). Of these, 92.0% said they would take the test if the diseases screened affected the lifespan of children or infants and 78.8% said they would take the test if the diseases screened for were chronic and required them to be a full-time carer. Sixty per cent said they would take the test if the test screened for adult-onset diseases (table 3A). Of those participants willing to take the test, 79.7% indicated that they would want to access the test through their general practitioner. Most participants (85.4%) reported that they would not access the test and results via the mail and/or online ordering, midwives (81.3%) or gynaecologist or obstetricians (57.8%). Finally, 75.1% reported that they would take the test if it cost <$A200 (table 3A).
Declining the test
Only 10.1% of participants reported that they would decline the PCS test if it were offered to them. A third of these participants had no interest in finding out their genetic information and 28.6% believed that the test would not be useful for them (table 3B).
Being unsure about the test
Overall, 22.4% of participants indicated that they were unsure about taking the test if PCS was offered to them. As a follow-up to this question, 67.7% said they would like more information about the diseases tested, 46.8% said they would like more information about the technology used and 43.5% said they would like more information about postscreening options (table 3C).
Level of genetic knowledge among participants
Most participants (n=645; 77%) correctly answered at least 10 out of the 21 genetic knowledge questions. Two-thirds of participants answered key concepts pertaining to carrier screening correctly (table 1). Participants did not fare well in advanced genetic concepts regarding probability (answered correctly=13%, question 6) and inheritance of mutations (answered correctly=35%, question 13). Almost half of participants correctly answered that their child may still have a genetic disease even if both parents tested negative for the disease. Misconceptions about diseases associated with lifestyle choices were also identified, with 63% thinking that one cannot develop harmful genetic mutations from lifestyle choices and 83% thinking that spina bifida is caused only by genetic mutations (table 1 and online supplementary table S1).
Factors associated with the intention to take a PCS test
Education level was positively associated with intention to take the test. Those who had completed postschool vocational education were twice as likely to reject the test than take it compared with those who had completed year 12 or equivalent (OR=2.18, 95% CI 1.09 to 4.32, p=0.03) (see online supplementary table S5). Income was also significantly associated with taking the test. Participants who earned an annual income of $A80 000–$A125 000 compared with participants with an annual income of $A0–$A30 000 were two times more likely to take the test (OR=2.27, 95% CI 1.07 to 4.83, p=0.033). Those who were religious, or spiritual were three times more likely to reject the test when compared with those who were not religious or spiritual (OR=3.05, 95% CI 1.06 to 8.83, p=0.039) (see online supplementary table S5). Age, gender, relationship status and intentions of becoming a parent were not significantly associated with taking the test (table 2).
Prior knowledge and genetic knowledge factors
A third of participants (n=239) had heard about PCS, reflecting prior knowledge or awareness of the screening test. Prior knowledge was shown to be significantly associated with intention to take the PCS test (see online supplementary table S6). Participants who had prior awareness of the test were more likely to either take or reject the test, compared with those who were unsure of their intentions (take the test: OR=2.53, 95% CI 1.65 to 3.89, p≤0.001; reject the test: OR=2.20, 95% CI 1.20 to 4.05, p=0.011) (see online supplementary table S7). Knowing about PCS from family members or searching through the internet were strongly associated with intention to take a PCS test (p≤0.05). Among participants who had heard about the PCS test from family members, 93.2% would take the test compared with 6.8% who were unsure. Similarly, among participants who know the test through internet searches, 91.1% will take the test compared with 8.8% who are unsure (see online supplementary table S6).
The likelihood of an individual accepting the PCS test compared with rejecting it was significantly higher for people who had ‘high’, ‘good’ and ‘some’ genetic knowledge compared with those who had ‘low’ genetic knowledge (all p≤0.05) (tables 4A and online supplementary table S8). The participants who had ‘good’ genetic knowledge were seven times more likely to take the test (OR=7.62, 95% CI 3.04 to 19.14, p=<0.001) while those with ‘high’ genetic knowledge were only four times more likely to take the test (OR=4.15, 95% CI 1.68 to 10.28, p=0.002) (table 4A).
Intention not to use carrier screening in individuals with ‘high’ genetic knowledge was associated with four concerns: 1) negative impact on my family members, 2) confidentiality of genetic information, 3) discrimination based on genetic result and 4) negative implications to obtain health, life and/or disability insurance (see online supplementary table S9).
Individuals were more likely to take the PCS test than reject it with every one unit increase in the score (ie, from 4 to 5 on the Likert scale) for factor 2 ‘equity of access and empathy’, factor 3 ‘feelings about individuals with a genetic disorder’ and factor 4 ‘test-related concerns’ (all p≤0.001).
Individuals were less likely to take the test with every one unit increase in the score for factor 1 ‘apprehension and religious beliefs’ (OR=0.20, 95% CI 0.13 to 0.32, p≤0.001).
There were also some individuals who were more likely to be unsure about their intentions to take the test rather than rejecting the test with every one unit increase in the feelings about individuals with a genetic disorder score (OR=1.43, 95% CI 1.02 to 2.01, p=0.037) (table 4B).
Association between genetic knowledge and attitudes towards PCS
Increases in genetic knowledge (eg, from ‘some’ genetic knowledge to ‘good’ genetic knowledge) were positively correlated with individuals’ scores on the equity of access and empathy factors and test-related concerns factor (OR=2.36, 95% CI 1.96 to 2.84, p≤0.001; OR=2.72, 95% CI 2.19 to 3.39, p≤0.001, respectively) (figure 1).
Individuals who had ‘high’ genetic knowledge but were less likely to take the test had higher mean scores for statements in attitude factor 1 ‘apprehension about the test and religious beliefs’ compared with those with ‘high’ genetic knowledge who said they intended to use carrier screening. In addition, these individuals also had lower mean scores for statements in attitude factors 2 ‘equity of access and empathy’, 3 ‘feelings about individuals with a genetic disorder’ and 4 ‘test-related concerns’ (see online supplementary table S10).
As genetic knowledge decreased, scores for factor 1 ‘apprehension about the test and religious beliefs’ increased (OR=2.78, 95% CI 2.26 to 3.43, ≤0.001) (table 4C).
Our study identified key factors associated with intention to participate in a PCS programme (see online supplementary figure S1). Higher levels of genetic knowledge correlated significantly with PCS participation, consistent with previous studies.31 32 Of interest is the comparative decrease in intention to participate in a PCS test in participants who had ‘high’ genetic knowledge compared with those with ‘good’ genetic knowledge. Our results show that those who have ‘good’ genetic knowledge were seven times more likely to take the test while individuals with ‘high’ genetic knowledge were only four times more likely to take the test. This finding appears to be explained in part by participants concerns related to: 1) negative impact on my family members, 2) confidentiality of genetic information, 3) discrimination based on genetic result and 4) negative implications to obtain health, life and/or disability insurance. In addition, individuals with ‘high’ genetic knowledge who said they would not take the test scored more highly on factor 1 attitudes ‘apprehension about the test and religious beliefs’ and less highly on attitudes in relation to statements in the other three factors. This indicates that high genetic knowledge has limited influence on certain attitudes.
Issues around privacy and insurance therefore received the most number of responses among those who had ‘high’ levels of genetic knowledge and had no intention of taking the test. Since the introduction of expanded gene panels in screening programmes, similar concerns have been raised and identified in studies among health professionals and communities.6 13 35 38 This has resulted in calls for more transparent methods of ensuring confidentiality and privacy in order to minimise stigmatisation and social discrimination.39 Community education, public campaigns and more extensive pretest and post-test counselling have been suggested as methods to reduce social discrimination. Some authors have suggested that the introduction of an expanded carrier screening programme may reduce social stigma through the ‘universal test’ approach as opposed to targeting a single ethnic group.6
Similarly, genetic discrimination is recognised as an international phenomenon40 and can occur in different types of insurance covers such as health or life insurance.39 As such, legislation including a moratorium or the Oviedo Convention (which prohibits insurance companies from asking for any genetic test results from their applicant) are in place in certain countries, to protect their citizens from genetic discrimination.40 A moratorium temporarily restricting insurers’ use of genetic information exists in Australia and the UK.41 Under the moratorium, insurers cannot request their applicants to undergo a genetic test or request previous results for policies under certain amounts, but applies only to health and not life insurance in Australia. As a result, even though participants in our study may have an understanding that being a carrier does not implicate or have an impact on their health, there is no legal framework in Australia to safeguard and protect consumers against discrimination by life insurance companies. As shown, this fear may reduce intentions to participate in carrier screening programmes. Otlowski et al suggested that continuous monitoring of policies on insurance through any available common metrics and instruments will aid in the comparative studies of long-term impact on individuals, families and the community.40
Previous studies have highlighted that knowledge, attitude and personal values affect informed decision-making.32 42 Consistent with other studies,32 34 35 our data showed that 77.5% of participants had at least ‘good’ genetic knowledge. Highly educated individuals tend to have higher levels of genetic knowledge and a deeper understanding of genetic concepts. However, a proportion of individuals with ‘good’ genetic knowledge answered incorrectly questions that tested understanding (see online supplementary table S11) such as ‘if both members of a couple test negative for a specific disorder, their child may still have a disorder’. These statements reflect core principles in PCS and without a sound understanding, informed decision-making may be compromised. This result suggests that having ‘good’ knowledge may not be sufficient to understand and appreciate core concepts of PCS and may impact the ability to make informed decisions. The community may benefit from a tailored education programme to reduce misconceptions and improve genetic literacy.
Participants who had positive attitudes towards the test tended to agree with statements such as ‘Provides couples with reproductive choices’ or ‘It is difficult for a person with a severe recessive disease to have a very good life’. These individuals were at least twice as likely to take the test, consistent with previous studies showing that positive attitudes towards a screening test generally correlates significantly with participation rates.32 33 Conversely, individuals who were more agreeable to statements such as ‘Is morally unacceptable’ or ‘Will do more harm than good’ were less likely to take the test. These individuals were also more likely to have lower levels of genetic knowledge (table 4C). Similarly, we found that with increasing genetic knowledge, individuals tend to agree more with statements such as ‘Provides couples with reproductive choices’ as well as statements about ‘A post-test consultation with a genetic counsellor would be essential’ (figure 1). However, deeply personal values and beliefs such as "I think it is wrong to knowingly bring a child with a severe recessive disease into the world" and religious values are not influenced by genetic knowledge (table 4C). Our results also show that religious individuals are three time more likely to reject the test than participate. Overall, these findings highlight that increasing genetic knowledge may have a positive effect on certain attitudes, but not personal values and beliefs, which go on to influence participation rates.
We also show that prior knowledge of PCS before taking the test is associated with increased likelihood of participation (p≤0.001) (see online supplementary table S6). Further investigation indicates those who had prior awareness of PCS reported that they would either take the test or reject it (see online supplementary table S7). This conflicting result may suggest that those who will take the test probably have a positive attitude towards the test, perceived susceptibility to the disease or probably want to avoid having an affected child, as studies have suggested.43 Conversely, those who decline the test may feel that they are not at risk, or that a lack of family history is sufficient to convince them that such tests are unnecessary.38 Our results show that who individuals learn about the test from is important. Although numbers are small, if an individual learnt about the test through a family member, none would not take the test (see online supplementary table S6). The high level of intention to participate in those who had heard about PCS from a family member, suggests the social environment is strongly associated with an individual’s intention to participate in PCS and is consistent with other studies examining how an individual’s beliefs about a particular behaviour are influenced by the judgement of significant others (eg, family).44
More than two-thirds of our participants indicated intentions to use a PCS test. Three previous studies have shown about a third of their participants were willing to take the test.2 22 38 The significant increase in media coverage of PCS in Australia in the months prior to the survey45 46 may have raised awareness about PCS testing, and highlighted the benefits of adopting carrier screening before pregnancy. This may have encouraged more participants to consider taking PCS. It was not surprising that most participants in the Netherlands study preferred to access the test through their general practitioner (GP) and trust their opinions, given the strong primary healthcare structure in the Netherlands. Similarly, in Western Australia, almost 80% of our participants preferred to access the test through their GP. Most healthy Australians will see a GP at least annually, whereas interactions with medical specialists (eg, obstetricians) are less frequent. Interestingly, most of our participants rejected all other options including accessing the test through a gynaecologist or obstetrician, or accessing the test and results directly via the mail and/or online ordering. This may suggest confidence in our primary healthcare structure or simply that GPs provide the greatest convenience to the community.
This cross-sectional study provides comprehensive data on key factors affecting intentions to participate and attitudes towards PCS in Western Australia. We show that increased genetic knowledge and a positive attitude to genetic testing are instrumental in influencing intentions to participate and whether those decisions are informed. Concerns surrounding social issues because of screening were also raised.
The study nevertheless has limitations which might bias the findings. The demographics may not fully represent the Western Australian population, although it is indicative of the cohort to whom PCS would be most relevant. As participants could choose whether to participate, self-selection bias may mean that the respondents included an over-representation of individuals both strongly for and against PCS. In addition, other variables that may affect the uptake interest such as perceived behavioural control (how easy or difficult it is for an individual to perform the particular behaviour),44 availability of reproductive options or considerations around termination of pregnancy were not directly measured.
It is well known that intentions to do a behaviour and actual participation are not always in alignment, and may be influenced by factors such as social barriers (eg, stigmatisation, discrimination), familiarity of diseases tested and awareness or perceived benefit.23 Consequently, tailored community education programmes addressing the issues identified in this study would be required to ensure individuals with different levels of genetic knowledge are sufficiently informed to make decisions regarding PCS testing. This study highlights that continuous education of GPs, and thus the community, is crucial to reduce misconceptions and to raise awareness about PCS in the community. Increasing genetic literacy among those who have a positive attitude towards screening in turn might improve uptake. Our findings thus inform how PCS might best be implemented into the future.
Supplementary information is available at the Journal of Medical Genetics website.
The authors would like to thank all funding bodies for their continuous support.
Contributors RO, DH, PC, CM, GR, NGL designed the study. RO designed, analysed and administered the survey instrument, drafted the manuscript, coordinated the revisions and submitted the manuscript. DH, AR, HC, CM, GR, NGL participated in the data analysis. AR provided technical expertise in the data analysis. All authors commented on various versions of the manuscript, agreed on the final version to be published and can attest to the integrity of the work.
Funding HC is supported by a National Heart Foundation Future Leader Fellowship (#100794). NL is supported by an Australian National Health and Medical Research Council Principal Research Fellowship (APP1117510). GR is supported by an Australian National Health and Medical Research Council Career Development Fellowship Level 1 (APP1122952). RO is supported by an Australian Postgraduate Award and an Australian Genomics Health Alliance PhD top-up award.
Disclaimer The funding agencies had no involvement in the design, completion or writing of this study.
Competing interests None declared.
Patient consent Not required.
Ethics approval Ethics approval for the study was granted by the Human Research Ethics Committee of the University of Western Australia (RA/4/1/8847).
Provenance and peer review Not commissioned; externally peer reviewed.
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