Spinal Muscular Atrophy (SMA)


Spinal muscular atrophy (SMA) is a rare genetic neurodegenerative disease with an incidence of approximately 1 in 6000 to 1 in 10,000 live births.1 The prevalence of the disease is estimated to be 1 to 2 in 100,000 people across all populations and ethnicities.2  SMA is the most common genetic condition affecting children and the No. 1 genetic cause of death in infants.3

Importance of Patient Education

Patient education for any disease is important and necessary because patients’ understanding of their condition and its care can ensure better adherence to treatment. Research has shown that a better understanding of the disease can enhance patients’ self-care and self-esteem and reduce anxiety and disruption in daily functioning.4

Patient education can also provide advantages for health care providers, including decreased liability and increased patient satisfaction.

In the case of genetic diseases such as SMA, patient education can underscore the importance of genetic testing to identify carriers and diagnose patients so that treatment can start as soon as possible.

Newborn Screening for SMA

Even though there is currently no cure for SMA, disease-modifying treatments are available. Newborn screening can ensure a patient starts treatment before irreversible neuronal damage has occurred.5 The treatments are nusinersen (Spinraza®), onasemnogene abeparvovec (Zolgensma®), and risdiplam (Evrysdi™).6 Newborn screening may also allow a patient to enroll in a clinical trial that is testing an experimental treatment.5

In the US, 36 states currently screen for SMA, and 71% of all babies are screened for the disease at birth.7 The target is 100% implementation of newborn screening for SMA across all states.

SMA Carrier Screening

The carrier frequency of SMA is estimated to be as high as 1 in 40 to 1 in 60 people.1 The American College of Medical Genetics and Genomics (ACMG) recommends carrier screening be offered to all couples.8

Most cases of SMA are caused by homozygous deletions in the SMN1 gene. The disease is inherited in an autosomal recessive manner.9 Two carriers, therefore, have a 25% chance of having a child with the disease and a 50% chance of having a child who is a carrier and can pass the disease onto the next generation. 

A population-based SMA carrier screening can identify couples at risk for having a child with SMA and allow them to make informed choices about their reproductive options.5 These include prenatal genetic testing using amniocentesis or chorionic villus sampling, and in vitro fertilization with preimplantation genetic testing. Genetic counseling should also be offered to carriers or families affected by the disease.  

A study by Prior et al. has shown that most people did not know about SMA before attending a genetic counseling session.5 Most of the people who responded to a survey about factors that contributed to their decision to have a genetic test found the patient education material that they were provided with very helpful or somewhat helpful. Almost all patients said they were happy that they pursued screening, and almost all the patients who underwent screening said they would pursue screening if the testing was covered by insurance.

2017 International Standards of Care for SMA

To provide patients with the best possible care and improve their quality of life and life expectancy, the international standard of care committee for SMA published in 2007 a consensus statement for the standard of care in SMA.10 The statement was then updated in 2017 to include more information about the natural history of SMA, advancements in medical care, and the high number of clinical trials.11,12 

Based on the  2017 international standards of care for SMA, a medical guide for SMA patients and their families was produced and translated into 7 languages.13 The guide aims to ensure that all people affected by SMA are aware of the latest medical care standards.

The guide contains patient education material about the genetics of SMA and its diagnosis, different organ systems it may affect, treatments, medications, emergency care, ethics, and choices available to patients.

Medical professionals can recommend the guide, which is freely available, to their patients and their families to ensure they are up to date with the latest in the field of SMA care. Medical professionals who are not familiar with the disease will also find the guide useful to familiarize themselves with the different therapeutic approaches available to patients.

Reviewed by Michael Sapko, MD on 7/1/2021

References

  1. D’Amico A, Mercuri E, Tiziano FD, Bertini E. Spinal muscular atrophy. Orphanet J Rare Dis. 2011;6:71. doi:10.1186/1750-1172-6-71
  2. Verhaart IEC, Robertson A, Wilson IJ, et al. Prevalence, incidence and carrier frequency of 5q–linked spinal muscular atrophy – a literature review. Orphanet J Rare Dis. 2017;12:124. doi:10.1186/s13023-017-0671-8
  3. Spinal muscular atrophy (SMA). Boston Children’s Hospital. Accessed June 4, 2021.
  4. Fernsler JI, Cannon CA. The whys of patient education. Semin Oncol Nurs. 1991;7(2):79-86. doi: 0.1016/0749-2081(91)90085-4
  5. Prior TW, Snyder PJ, Rink BD, et al. Newborn and carrier screening for spinal muscular atrophy. Am J Med Genet A. 2010;152A(7):1608-1616. doi:10.1002/ajmg.a.33474
  6. Newborn essentials: does your state screen for SMA? Cure SMA. Accessed June 4, 2021.
  7. Newborn screening for SMA. Cure SMA. Accessed June 4, 2021.
  8. Committee opinion No. 691: carrier screening for genetic conditions. Obstet Gynecol. 2017;129(3):e41-e55. doi:10.1097/AOG.0000000000001952
  9. Causes/Inheritance. Muscular Dystrophy Association. Accessed June 4, 2021.
  10. CH Wang, Finkel RS, Bertini ES, et al. Consensus statement for standard of care in spinal muscular atrophy. J Child Neurol. 2007;22(8):1027-1049. doi:10.1177/0883073807305788
  11. Mercuri E, Finkel RS, Muntoni F, et al. Diagnosis and management of spinal muscular atrophy: part 1: Recommendations for diagnosis, rehabilitation, orthopedic and nutritional care. Neuromuscul Disord. 2018;28(2):103-115. doi:10.1016/j.nmd.2017.11.005
  12. Finkel RS, Mercuri E, Meyer OH, et al. Diagnosis and management of spinal muscular atrophy: part 2: Pulmonary and acute care; medications, supplements and immunizations; other organ systems; and ethics. Neuromuscul Disord. 2018;28(3):197-207. doi:10.1016/j.nmd.2017.11.004
  13. A guide to the 2017 International Standards of Care for SMA. Treat-NMD. Accessed June 4, 2021.
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