This study explored understanding of and attitudes to genetic testing for inherited retinal disease in a large sample of affected adults. The aim was to collect data to inform inherited retinal disease services, improve information provision and assess current demand for genetic testing.
When participants were asked to self-rate their level of understanding of genetic testing for inherited retinal disease, a wide range of responses was obtained. The only subgroup difference in perceived understanding was due to education: those educated to college level or above reported a significantly greater understanding. In general, public understanding of genetic science appears to be variable.9
Many people have difficulty explaining the meaning behind the concepts of ‘genetics’ and ‘genes’, despite being familiar with the terminology.10
One study found that women, younger participants (18–44 years) and those with higher educational attainment were more likely to possess greater knowledge in this field.11
However, unlike this research, these studies were all conducted with the general public. Further exploration of understanding within patient samples is warranted to assess whether knowledge is greater in those affected by genetic conditions.
The majority of participants viewed genetic testing for inherited retinal disease very positively. Support was very strong for the provision of publicly funded diagnostic and predictive genetic testing. However, most participants were in favour of information provision and access to genetic counselling before genetic testing. These findings are consistent with existing research in similar patient groups.6
Support was less strong for genetic testing as part of reproductive planning. The use of preimplantation genetic diagnosis to achieve an unaffected pregnancy has been reported in cases of recessive Stargardt disease, severe RP and X-linked retinoschisis4
and prenatal testing has also been reported for Leber congenital amaurosis.3
Sizeable proportions of the current sample supported the use of genetic testing for reproductive planning purposes: 65% of participants supported carrier status testing, and 52% and 47% supported preimplantation and prenatal genetic testing for inherited retinal disease, respectively. Similar figures have been reported elsewhere.4
Participants’ comments provided additional important information on attitudes to preimplantation and prenatal testing. While approximately a half of the sample felt that these services should be available, they would not necessarily choose to use them themselves. This finding may help to explain the phenomenon of high hypothetical but low actual uptake of (predictive) genetic testing.16
This pattern has been consistently observed in populations affected by Huntington disease17
which has been considered a model of understanding the attitudes towards (predictive) testing for late-onset conditions with no treatment or cure19
such as many inherited retinal diseases.12
Our research suggests that when planning genetic testing services, patient attitudes should be explored in depth.
Of interest in our study was stronger support for carrier status testing and reproductive planning in British Asian participants. This may reflect greater awareness of the risk in communities in which inherited retinal disease is more common.20
For some participants, genetic status might be one of the considerations when arranging a marriage. Others have explored genetic testing issues in similar populations21
who might be marginally more affected by autosomal recessive genetic conditions due to a proportion of consanguineous marriages.
Several common themes emerged in describing the potential benefits of testing. Frequently cited benefits included greater understanding and knowledge about the genetic basis of the condition, as well as early access to emerging therapies. Participants also reported benefits to family members and future generations, as well as to society in general. They were often aware of limited personal benefit but felt that the information gained from testing may contribute to treatments of others in the future.
Participants were also asked about potential negative consequences of genetic testing. Several suggestions were offered, although a substantial number of respondents reported that they did not consider there to be any drawbacks. Reported disadvantages included the potential impact upon family relationships (ie, feelings of guilt from passing a condition on or blame in those who have inherited it) and the potential for results to be used to terminate pregnancies or increase insurance premiums. A substantial number of participants felt anxiety about their future. Many had ethical considerations. Emotional consequences of a result were frequently mentioned as disadvantageous. Other studies provide context to this finding. Mezer et al12
reported emotional distress in 57% of affected adults and their family members when recollecting their own predictive testing as children. By contrast, an investigation of a large family undergoing testing for hereditary myocilin glaucoma found no adverse impacts of predictive testing 5 years following initial counselling23
and a systematic review of various genetic conditions also showed no long-term sequelae either for carriers or non-carriers.24
Some limitations of the study must be acknowledged. Our sample was self-selecting and it is therefore possible that participants were more motivated and held more favourable attitudes towards genetic testing than those who were invited but opted not to participate. Due to the recruitment methods employed, it is also acknowledged that study participants were currently engaged with the healthcare system and/or voluntary organisations. Several participants pointed out that whereas they wanted to know and were accepting of their diagnosis, other family members were not, and preferred ignorance of their genetic status. It is therefore to be expected that they may hold views different to those held by the participants in our research. Nevertheless, the strengths of the study include the large number of affected individuals, with a range of clinical diagnoses and demographic characteristics.
Individuals with inherited retinal disease had expressed strong support for the provision of genetic testing, particularly diagnostic and predictive testing. Most are aware of a number of possible benefits but not the potential negative consequences. There is a need for the provision of information, in a format accessible to those with visual impairment, and access to genetic counselling before testing and this would be in keeping with patients’ expectation. Our results indicated that information may be most effectively targeted toward less educated individuals who reported lower levels of understanding and greater uncertainty around prenatal testing. However, support for genetic testing for inherited retinal disease is not universal and many participants (typically those with a higher level of education) were in favour of access for others but not by themselves, particularly in relation to prenatal testing for reproductive planning.