Spinal Muscular Atrophy (SMA) is an incurable, inherited neuromuscular disease typified by progressive weakness and, in the most severe forms, death due to respiratory failure.1 SMA is the second most common congenital disease with an estimated worldwide incidence of approximately 1 in 10,000 live births.2 Given that the inheritance pattern of SMA is autosomal recessive,1 the high birth incidence rate of SMA means that there are a high number of asymptomatic carriers, on average 1 in 503 though some ethnic populations appear to have higher frequencies.2 The genetics of SMA can present unique challenges,4,5 and thus given its high incidence2 and its biological idiosyncrasies,6 there is a widespread and specific need for genetic counseling in SMA.6,7
Genetic counselors provide many useful services to referred individuals as indicated below:8
- They discuss family planning options with at-risk families
- They provide statistical information about the likelihood of having a child with SMA
- They explain genetic testing results to ensure full understanding of the test’s implications
- They provide basic information about SMA like symptoms, disease course, and prognosis
- They identify at-risk individuals
- They can recommend follow-up testing if needed
Consensus guidelines recommend that genetic counseling be included among multidisciplinary services offered to parents who have children diagnosed with, or suspected of having, SMA.9 The American College of Obstetricians and Gynecologists advises offering genetic counseling to identified all known SMA carriers, anyone who sought SMA genetic testing, and anyone requesting fetal testing.10 Despite these recommendations, genetic counseling and offers of testing to at-risk families are particularly lacking in SMA.4,11 A survey of how parents received their diagnosis and genetic counseling revealed the primary source of information was their child’s neurologist and that the shared information was not optimally matched to families’ needs.12 Trained genetic counselors are ideally suited for conveying the complexities of SMA to families.13 The diagnostic odyssey in SMA can be long in duration14 and ultimately achieving a SMA diagnosis is traumatic for families.15 Genetic counselors should possess SMA-specific knowledge to ensure effective communication with parents and patients.13 A single interaction with a trained counselor is not an assurance of parents being aware of even basic facts such risk of recurrence in future offspring,8 a finding that highlights the need for better parental education before and after genetic testing,16 especially in SMA.12 A follow-up letter after genetic counseling reinforces understanding of topics covered in the counseling session.8
Prenatal screening,17 universal newborn testing,18,19 and genetic testing of asymptomatic siblings of patients with SMA9 have been controversial topics because of ethical dilemmas given the absence of proven interventions, but these topics may be revisited in the near future with the approval of effective therapies for SMA.19
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3. Sugarman EA, Nagan N, Zhu H, et al. Pan-ethnic carrier screening and prenatal diagnosis for spinal muscular atrophy: Clinical laboratory analysis of >72,400 specimens. Eur J Hum Genet. 2012;20(1):27-32.
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18. Phan HC, Taylor JL, Hannon H, Howell R. Newborn screening for spinal muscular atrophy: Anticipating an imminent need. Seminars in perinatology. 2015;39(3):217-229.
19. Lin PJ, Yeh WS, Neumann PJ. Willingness to pay for a newborn screening test for spinal muscular atrophy. Pediatr Neurol. 2017;66:69-75.