The Changing Landscape of SMA Poses Ethical Considerations for Screening and Treatment

Amid a changing landscape for spinal muscular atrophy (SMA), Australian researchers have highlighted the ethical considerations stakeholders face when it comes to both screening and treating the disease, including how the severity of the disease is taken into account.

Through these ethical considerations, the researchers highlighted the importance of collaborating with patients and their caregivers, including in decisions about treatment eligibility as more longitudinal evidence becomes available for treatments like risdiplam (approved in 2020) and nusinersen (approved in 2016), which showed improvements in motor function and survival.

“While new therapies for SMA are extremely welcome, the rapid pace of their development is creating ethical complexity for healthcare professionals and families. The long-term effects and outcomes of new therapies for SMA remain uncertain,” the study authors wrote in Australian Journal of General Medicine. “While they may prevent further decline, disease-modifying treatments are not a cure for SMA, and children who begin treatment after symptoms appear may continue to live with impairment. It is important to manage parents’ optimism and hope and to ensure that the benefits are not overstated while the possible harms are underestimated.

Access to these treatments also poses challenges, the researchers explained, citing restrictions related to age, place of treatment, SMN2 copies and disease progression. For example, patients who are presymptomatic with at least 3 copies of SMN2 cannot be reimbursed for disease-modifying treatments.

In their article, the researchers also raise ethical considerations for SMA before and immediately after birth. As with other genetic diseases, SMA is included in most commercial panels for reproductive carrier screening (RCS). If it is determined that a child is likely to have SMA, parents have the option of performing other interventions, including preimplantation genetic testing where they choose an embryo without 2 copies of the SMN1 pathogenic variant.

Prenatal diagnosis is also used to help a couple prepare for or avoid the birth of a child with SMA.

The researchers noted that while RCS gives parents the ability to make their own reproductive decisions, the process also has ethical concerns, with the group recommending that couples be referred to appropriate RCS providers who are available for provide advice after the test.

“For SMA in particular, the identification of carriers of a pathogenic variant in the SMN1 The gene alone does not predict the severity of SMA a child may develop,” they explained. “Another consideration is the broader debate on the place of disability and difference in society. It has been argued that prenatal screening is unfairly discriminatory, particularly when there is a variable presentation. Reasons include an implicit goal of eradicating disability and decreasing diversity, thereby devaluing people living with genetic conditions such as SMA.

With an emphasis on early intervention, newborn screening (NBS) is recognized as another crucial opportunity for early disease detection, with countries around the world implementing NBS programs.

However, like RCS, the screening method also comes with controversy, such as in the case of a patient having more than 3 copies of SMN2leaving questions about the severity of the disease and uncertainty about when the patient will show symptoms and how and when should intervention be initiated.

Reference

Newson AJ, Dive L, Cini J, Hurley E, Farrar MA. Ethical aspects of the changing landscape of spinal muscular atrophy management in Australia. Aust J Gen Practice. 2022;51(3):131-135. doi:10.31128/AJGP-06-21-6028