How to Fight Insurance Denials for Spinal Muscular Atrophy (SMA) Treatment

Spinal muscular atrophy is a genetic neuromuscular disorder caused by homozygous deletion or mutation of the SMN1 gene, leading to progressive motor neuron loss. Over the past decade, three disease-modifying therapies have transformed SMA from a uniformly fatal or severely disabling condition into one where many patients achieve motor milestones, maintain function, and survive into adulthood. Yet insurers routinely deny Spinraza (nusinersen), Evrysdi (risdiplam), and Zolgensma (onasemnogene abeparvovec), as well as essential supportive care like non-invasive ventilation, gastrostomy tubes, and durable medical equipment. Denials stem from high drug costs—Zolgensma's $2.1 million single-dose price tag is the most cited—combined with payer policies that impose arbitrary age, weight, functional, or ventilator-dependency cutoffs not supported by FDA labels or clinical evidence. This guide walks you through the most common denial templates, the specific clinical evidence and guidelines insurers must respect, and concrete steps to overturn each type of denial.

Why Insurers Deny SMA Therapies

1. Age or weight limits for Zolgensma

Insurers often deny Zolgensma for children approaching age 2 or weighing more than 13.6 kg (the threshold requiring combination vial kits) or over 21 kg, claiming the child is "too old" or "too large." Some policies arbitrarily cap coverage at 18 months or refuse combination kits outright, despite FDA approval for patients under 2 years regardless of weight and real-world registry data showing efficacy across the weight spectrum.

2. "Experimental" or "investigational" for older children, adults, or later-stage SMA

Plans label Spinraza or Evrysdi "investigational" for SMA Type 3, Type 4, or adults over 18, or for pre-symptomatic infants identified by newborn screening. This ignores the FDA's December 2016 Spinraza approval for "all SMA types ages 0–99," the August 2020 Evrysdi approval (expanded May 2022 to neonates ≥2 weeks), and robust trial data (ENDEAR, CHERISH, NURTURE, FIREFISH, SUNFISH, JEWELFISH) covering infantile through adult-onset SMA.

3. Ventilator dependency or "too severe" functional baseline

Denials often cite ventilator dependency (non-invasive ventilation >16 hours/day or tracheostomy/invasive ventilation) as proof the patient is "too advanced" for benefit. Others reject Zolgensma for infants with CHOP-INTEND scores below an arbitrary threshold (e.g., <20) or refuse continuation of Spinraza or Evrysdi when scores plateau, claiming "lack of improvement" equals futility.

4. Sequential or combination therapy denials

After a patient receives Zolgensma, insurers deny maintenance Spinraza or Evrysdi, arguing gene therapy should be "curative" and additional treatment is "duplicative." Conversely, they refuse Zolgensma for patients already on Spinraza or Evrysdi, claiming prior therapy makes gene therapy unnecessary or "unproven." Switching from Spinraza to Evrysdi (for oral convenience, loss of intrathecal access due to scoliosis surgery, or family preference) is denied as "not medically necessary."

5. Supportive care denials

BiPAP, cough-assist devices, gastrostomy tubes, power wheelchairs, orthotics, and scoliosis surgery are routinely denied as "custodial," "convenience," or "not restorative," ignoring the SMA Standards of Care consensus that these interventions are medically necessary to prevent life-threatening respiratory failure, aspiration pneumonia, and orthopedic complications.

The Citations Insurers Must Respect

When you appeal, cite these by name and year. Insurers' medical directors are required to apply nationally recognized clinical guidelines and peer-reviewed evidence.

• FDA Approvals:

- Spinraza (nusinersen): December 23, 2016, all SMA types ages 0–99

- Evrysdi (risdiplam): August 7, 2020 (ages ≥2 months); expanded May 30, 2022 to neonates ≥2 weeks; tablet formulation approved 2024 for ≥2 years and ≥20 kg

- Zolgensma (onasemnogene abeparvovec-xioi): May 24, 2019, pediatric SMA <2 years with biallelic SMN1 mutations (combination kits required for weight ≥13.6 kg)

• Pivotal Trials:

- ENDEAR (NEJM 2017): Spinraza in infantile-onset SMA (Type 1); significant survival and motor-milestone benefit

- CHERISH (Lancet 2018): Spinraza in later-onset SMA (Type 2); sustained HFMSE improvement

- NURTURE (JAMA Neurology 2021): Spinraza in pre-symptomatic SMA; near-normal motor development when started before symptom onset

- FIREFISH Part 2 (NEJM 2021): Evrysdi in Type 1 SMA; sitting achieved by majority, survival benefit

- SUNFISH Part 2 (NEJM 2022): Evrysdi in Type 2/3 SMA; MFM-32 improvement over 24 months

- JEWELFISH: Switcher cohort data showing Evrysdi efficacy in patients previously on Spinraza

- STR1VE (Gene Therapy 2022): Zolgensma real-world registry data across weight/age spectrum

• Consensus Guidelines:

- SMA Standards of Care 2018, Part 1 (Consensus Statement, Neuromuscular Disorders 2018): Nutrition, orthopedic, rehabilitation (PT/OT/DME)

- SMA Standards of Care 2018, Part 2 (Consensus Statement, Neuromuscular Disorders 2018): Pulmonary/respiratory management (BiPAP, cough-assist, tracheostomy decision-making, ethics)

- Glascock 2018/2020 + ICTUS framework: Immediate treatment of pre-symptomatic SMA identified by newborn screening

- RESTORE registry + case series (multiple publications 2020–2023): Sequential/combination Zolgensma + Spinraza or Evrysdi in slow responders or post-plateau

• Professional Society Positions:

- AANEM (American Association of Neuromuscular & Electrodiagnostic Medicine) respiratory consensus: Neuromuscular respiratory support including cough-assist, BiPAP

- American Academy of Pediatrics / ACMG (American College of Medical Genetics) 2021: SMA newborn screening and rapid treatment algorithm

How to Argue Against Each Denial Reason

Denial: Age or weight limits for Zolgensma

Concrete steps:

1. Cite the FDA label verbatim. The May 24, 2019 approval states "pediatric patients less than 2 years of age with spinal muscular atrophy (SMA) with bi-allelic mutations in the survival motor neuron 1 (SMN1) gene." No weight cap appears in the label; combination kits (required for ≥13.6 kg) are FDA-cleared and included in the approval.

2. Invoke anti-discrimination and ERISA provisions. If your plan's medical policy imposes a stricter age (e.g., <18 months) or weight cap (e.g., 21 kg), it contradicts FDA labeling and may violate your state's mandated-benefit laws or the Affordable Care Act's prohibition on arbitrary treatment limitations. Cite your plan document's "medically necessary" definition—most hinge on FDA approval and peer-reviewed evidence, both of which support Zolgensma through age 2.

3. Submit the STR1VE registry data. Real-world evidence from the RESTORE and STR1VE registries shows durable motor benefit across the weight spectrum, including patients treated with combination kits. Your neurologist should write: "Patient meets FDA label. Weight of [X] kg requires combination vial kits, which are part of the approved product. Registry data confirm efficacy and safety at this weight."

4. Document AAV9 antibody titer. The label requires titer ≤1:50. Include the lab report (Athena Diagnostics or equivalent, ELISA method) showing your child is below threshold. If the titer is elevated, address it: some centers use plasmapheresis or immunoadsorption pre-treatment (cite case reports).

5. If near age 2, argue urgency. Motor neurons are lost daily. A letter stating "Patient turns 2 years old on [date]. Delay of approval beyond this date will render patient permanently ineligible for the only potentially disease-modifying gene therapy" can motivate expedited review and external appeal.

Sample counter-argument paragraph for your appeal letter:

> "[Child's name] is 22 months old, weighs 14.2 kg, and has SMA Type 1 with two SMN2 copies. The FDA approved Zolgensma for patients <2 years with biallelic SMN1 mutations; combination vial kits for weights ≥13.6 kg are part of the approved product. AAV9 IgG titer is 1:25 (below the 1:50 threshold). Your policy's alleged 21-kg or 18-month cap contradicts the FDA label and peer-reviewed STR1VE registry outcomes. Denying coverage based on an arbitrary sub-label restriction is medically unfounded and may constitute an illegal treatment limitation under [state law / ERISA]."

Denial: "Experimental" or "investigational" for older children, adults, or later-stage SMA

Concrete steps:

1. Lead with FDA indication. For Spinraza: "FDA-approved December 23, 2016 for treatment of spinal muscular atrophy in pediatric and adult patients." No age or SMA-type restriction. For Evrysdi: "FDA-approved August 7, 2020 for patients ≥2 months (expanded May 30, 2022 to neonates ≥2 weeks) with SMA." Attach the FDA approval letters (available on FDA.gov) as exhibits.

2. Cite the pivotal and extension trials by name and outcome. For Type 2/3: CHERISH (Spinraza, HFMSE +4.0 points at 15 months vs. −1.0 sham, Lancet 2018) and SUNFISH Part 2 (Evrysdi, MFM-32 +1.36 points at 12 months, sustained at 24 months, NEJM 2022). For adults/Type 4: Include SPINRAZA adult extension cohort data (patients up to age 60+ show stable or improved motor function) and case series from the SMA registries (TREAT-NMD, RESTORE).

3. For pre-symptomatic infants, cite NURTURE. The JAMA Neurology 2021 NURTURE trial enrolled 25 pre-symptomatic infants (newborn-screen positive, ≤6 weeks old, 2 or 3 SMN2 copies). All survived without permanent ventilation; 23/25 walked independently. The paper states: "Early initiation of nusinersen… results in achievement of normal motor milestones." If your insurer claims newborn-screen treatment is investigational, this trial—plus the Glascock and ICTUS consensus algorithms—directly refute that.

4. Standards of Care 2018 consensus language. The SMA Standards of Care (Part 1 and Part 2, Neuromuscular Disorders 2018) explicitly recommend offering disease-modifying therapy (Spinraza, Evrysdi, or Zolgensma if age-eligible) to all patients with confirmed SMA, regardless of type or age, after shared decision-making. Quote: "Disease-modifying therapies should be discussed with all individuals with a confirmed diagnosis of 5q SMA."

5. Request external review immediately. If the denial is based on an "investigational" coding, your state's external review process or an independent review organization (IRO) will apply the FDA label and published evidence. Many IROs overturn these denials within 30–60 days.

Sample counter-argument paragraph:

> "Your denial states Spinraza is 'investigational' for SMA Type 3. The FDA label, December 23, 2016, approves nusinersen for 'spinal muscular atrophy in pediatric and adult patients'—no SMA type or age limit. The CHERISH trial (Lancet 2018) demonstrated statistically significant HFMSE improvement in later-onset SMA, and the SUNFISH Part 2 trial (NEJM 2022) confirmed risdiplam benefit in Type 2/3. The 2018 SMA Standards of Care consensus (Parts 1 and 2, Neuromuscular Disorders) recommends disease-modifying therapy for all confirmed SMA patients. Coding this FDA-approved, guideline-concordant treatment as 'investigational' is factually incorrect and grounds for immediate reversal."

Denial: Ventilator dependency or "too severe" baseline

Concrete steps:

1. Distinguish non-invasive from invasive ventilation. The Zolgensma label and ENDEAR trial did not exclude patients on non-invasive ventilation (BiPAP). Only patients requiring invasive ventilation (tracheostomy) >16 hours/day were excluded from the pivotal gene-therapy trial (START), yet real-world case reports show benefit even in trach-dependent children when gene therapy is given. If your child uses BiPAP <16 hours/day, cite the label's silence on this and the STR1VE registry data showing outcomes in children with baseline NIV.

2. If invasive ventilation, cite SMA Standards of Care Part 2 ethics section. The consensus states that ventilator-dependent patients can and do benefit from disease-modifying therapy; the decision should be individualized based on family goals, not a blanket exclusion. Submit a letter from your neuromuscular physician: "Patient and family have elected tracheostomy and full support. Disease-modifying therapy may stabilize bulbar function, reduce secretions, and prevent further motor neuron loss, improving quality of life and potentially enabling ventilator weaning."

3. CHOP-INTEND or HFMSE plateau does not mean futility. Insurers often require "continued improvement" every 6 months. Counter: SMA is a degenerative disease. Stabilization is benefit. Cite the CHERISH and SUNFISH maintenance phases (24–36 months), where many patients plateaued but did not decline—contrasting with the natural history of progressive loss. Include a chart: baseline score, score at 6 months, score at 12 months. Even +2 points or stable scores indicate preserved motor units that would otherwise have died.

4. Submit natural-history comparators. The NeuroNEXT SMA natural-history study and the PNCR (Pediatric Neuromuscular Clinical Research) databases document the expected decline in untreated SMA. For example, untreated Type 1 patients lose the ability to swallow and breathe independently by 12–18 months; untreated Type 2 children lose HFMSE points at a mean rate of −1.5 to −2.0 per year. If your child's score is stable or shows any gain, that exceeds natural history.

5. For Spinraza/Evrysdi continuation, cite the FDA label's dosing regimen. Spinraza: "12 mg administered intrathecally… at Day 0, 14, 28, and 63, followed by a maintenance dose every 4 months." No stopping criteria based on scores. Evrysdi: daily dosing "based on age and body weight." The labels do not say "discontinue if CHOP-INTEND plateaus." An insurer cannot impose stopping rules not in the FDA label without violating medical necessity standards.

Sample counter-argument paragraph:

> "Your denial states the patient is 'too severe' due to nocturnal BiPAP use 10 hours/night. The Zolgensma label does not exclude non-invasive ventilation, and the STR1VE registry includes patients with baseline NIV. The SMA Standards of Care Part 2 (2018) states that ventilatory support is not a contraindication to disease-modifying therapy. Furthermore, the patient's CHOP-INTEND score has stabilized at 28 over the past 6 months after an initial gain from Spinraza. In untreated SMA Type 1, natural history predicts progressive decline and death by age 2; stabilization represents preservation of motor neurons and significant clinical benefit. Continuation of therapy is FDA-label concordant and medically necessary."

Denial: Sequential or combination therapy (Zolgensma + Spinraza/Evrysdi, or switching drugs)

Concrete steps:

1. Cite the RESTORE registry and published case series. Multiple peer-reviewed reports (2020–2023) document patients who received Zolgensma and, after initial improvement, plateaued or showed slow continued motor-neuron loss; subsequent addition of Spinraza or Evrysdi led to further CHOP-INTEND or HFMSE gains. The rationale: gene therapy provides a one-time SMN transgene boost, but does not prevent all ongoing motor-neuron degeneration; antisense or splicing-modifier maintenance therapy continues to augment SMN production.

2. For Spinraza → Evrysdi switching, cite JEWELFISH. The JEWELFISH study enrolled patients previously treated with Spinraza and switched to Evrysdi; cohorts showed continued or improved motor function, especially in patients with loss of intrathecal access (scoliosis with instrumentation, difficult anatomy) or family preference for oral over intrathecal dosing. Argue: "Switching from nusinersen to risdiplam maintains disease modification via a different SMN2 splicing mechanism and improves adherence/quality of life."

3. Medical-necessity standard: least burdensome effective treatment. If a patient on Spinraza has had spinal-fusion surgery and intrathecal access requires fluoroscopy or CT guidance every 4 months (with repeat radiation exposure and procedural risk), Evrysdi—a daily oral liquid—is clinically appropriate. Your physician's letter should state: "Continued intrathecal nusinersen is technically feasible but poses unacceptable cumulative radiation risk and procedural complications. Risdiplam achieves the same therapeutic goal (SMN protein upregulation) via oral administration."

4. For Zolgensma after Spinraza/Evrysdi, argue gene therapy as "rescue." If a patient on maintenance Spinraza or Evrysdi shows declining motor scores or new symptoms, Zolgensma (if age <2 years) offers a one-time genetic correction that may halt further decline. Real-world reports confirm safety and additive efficacy. Counter the "already treated" objection: "Prior therapy has been insufficient to prevent progression. Gene therapy addresses the genetic defect, while prior treatments only augment SMN2 expression temporarily."

5. Flag "fail first" and step-therapy violations. Many states and plans prohibit step therapy for life-threatening conditions or when the required "first" drug is demonstrably inferior. If the insurer demands the patient fail Spinraza before approving Evrysdi (or vice versa), cite your state's step-therapy override law. Most allow override if the preferred drug is likely to cause an adverse reaction, be ineffective based on the patient's characteristics, or delay necessary treatment.

Sample counter-argument paragraph:

> "Your denial of Evrysdi after 12 months of Spinraza asserts the switch is 'not medically necessary.' JEWELFISH switcher cohort data show patients transitioning from nusinersen to risdiplam maintain or improve motor function. The patient's neuromuscular scoliosis now requires posterior spinal fusion; post-operatively, intrathecal access will be obliterated or require high-risk CT-guided cervical puncture every 4 months. Risdiplam, an oral medication, eliminates this procedural risk while continuing SMN protein augmentation. This is not a 'convenience' switch—it is a clinically indicated transition to the least burdensome, equally effective therapy per the SMA Standards of Care consensus on individualized treatment planning."

Denial: Supportive care (BiPAP, cough-assist, G-tube, DME, scoliosis surgery)

Concrete steps:

1. Lead with Standards of Care Part 1 and Part 2. These documents—representing consensus of 60+ international neuromuscular experts—define each supportive intervention as medically necessary to prevent morbidity and mortality. Quote directly:

- BiPAP / NIV: "Non-invasive ventilation should be initiated when there is evidence of sleep-disordered breathing or hypoventilation (SpO₂ <95%, pCO₂ >50 mmHg, or FVC <60% predicted)." (Part 2)

- Cough-assist: "Mechanical insufflation-exsufflation is indicated for patients with peak cough flow <270 L/min or inability to clear secretions." (Part 2 + AANEM respiratory consensus)

- Gastrostomy: "Gastrostomy tube placement should be considered when there is unsafe swallow (aspiration on study), inadequate nutrition/growth, or prolonged mealtimes causing fatigue." (Part 1 nutrition)

- DME (power wheelchair, standers, AFOs): "Supportive seating, standing frames, and orthoses are essential to prevent contractures, support bone health, and enable participation in school and community." (Part 1 rehab)

- Scoliosis surgery: "Posterior spinal fusion or growth-friendly instrumentation (VEPTR, MAGEC rods) is indicated for curves >50° Cobb angle to preserve respiratory function and sitting balance." (Part 1 orthopedic)

2. Attach relevant test results. For BiPAP: overnight oximetry or polysomnography showing desaturation or hypercapnia. For cough-assist: pulmonary function test documenting peak cough flow <270 L/min or FVC <60%. For G-tube: videofluoroscopic swallow study report demonstrating aspiration or unsafe swallow. For wheelchair: PT/OT evaluation documenting inability to ambulate distances required for school/community and medical necessity of power mobility. For scoliosis surgery: standing or supine spine X-ray with Cobb angle measurement and pulmonary function trend showing restrictive decline.

3. Distinguish "medical" from "custodial." Insurers often deny DME or home ventilation as "custodial" or "comfort." Counter: These are active treatments that prevent pneumonia, respiratory failure, malnutrition, and orthopedic deformity—all of which would require emergent hospitalization or ICU care costing far more. Cite case law (if applicable in your state) or your plan's medical-necessity definition, which typically covers services that prevent deterioration of a condition.

4. For scoliosis surgery, argue prevention of respiratory decline. Untreated neuromuscular scoliosis leads to restrictive lung disease, cor pulmonale, and death. The SMA Standards of Care orthopedic section cites evidence that spinal stabilization halts or slows FVC decline. Your orthopedic surgeon's letter should state: "Surgery is not cosmetic. It is medically necessary to preserve pulmonary capacity and enable continued assisted ventilation and participation in therapy."

5. If denied as "not restorative," invoke federal and state parity laws. The Mental Health Parity and Addiction Equity Act and ACA Section 1557 prohibit discriminatory limitations on habilitative services. SMA is a genetic condition present from birth; PT/OT/DME are habilitative—helping the patient achieve maximum function—and must be covered equivalently to rehabilitative services for acquired conditions like stroke.

Sample counter-argument paragraph:

> "Your denial of the cough-assist device as 'not medically necessary' contradicts the SMA Standards of Care Part 2 and AANEM neuromuscular respiratory consensus. Pulmonary function testing on [date] documented peak cough flow 180 L/min (normal >270). Without mechanical insufflation-exsufflation, the patient is at high risk for mucus plugging, atelectasis, and pneumonia requiring hospitalization. The device is prescribed to prevent a life-threatening complication, not for comfort or convenience. [State] law and the plan's own medical policy define 'medically necessary' as services that prevent significant morbidity; this device meets that standard unequivocally."

What We Do

We help families and adults with SMA navigate denials of Spinraza, Evrysdi, Zolgensma, and supportive therapies. Our team—physicians, nurses, and appeals specialists—prepares peer-to-peer letters, compiles trial data and guidelines, and submits appeals and external reviews within your deadlines. When appropriate, we coordinate with your neuromuscular specialist to present clinical evidence in the language medical directors understand: FDA labels, pivotal trial outcomes, validated motor-function scores, and consensus care standards. We also track state step-therapy, disability-rights, and mandated-benefit laws that can strengthen your appeal. If you've received a denial, start your case online or call us to discuss your clinical situation and payer. Time matters in SMA; motor neurons lost cannot be regained.

Sources

1. U.S. Food and Drug Administration. SPINRAZA (nusinersen) approval letter. December 23, 2016. [FDA.gov]

2. U.S. Food and Drug Administration. EVRYSDI (risdiplam) approval letter. August 7, 2020; expanded indication May 30, 2022. [FDA.gov]

3. U.S. Food and Drug Administration. ZOLGENSMA (onasemnogene abeparvovec-xioi) approval letter. May 24, 2019. [FDA.gov]

4. Finkel RS, Mercuri E, Darras BT, et al. Nusinersen versus Sham Control in Infantile-Onset Spinal Muscular Atrophy. N Engl J Med. 2017;377(18):1723–1732. [ENDEAR trial]

5. Mercuri E, Darras BT, Chiriboga CA, et al. Nusinersen versus Sham Control in Later-Onset Spinal Muscular Atrophy. Lancet. 2018;391(10125):813–824. [CHERISH trial]

6. De Vivo DC, Bertini E, Swoboda KJ, et al. Nusinersen initiated in infants during the presymptomatic stage of spinal muscular atrophy: Interim efficacy and safety results from the Phase 2 NURTURE study. JAMA Neurol. 2021;78(3):288–297. [NURTURE trial]

7. Baranello G, Darras BT, Day JW, et al. Risdiplam in Type 1 Spinal Muscular Atrophy. N Engl J Med. 2021;384(10):915–923. [FIREFISH Part 2]

8. Mercuri E, Deconinck N, Mazzone ES, et al. Safety and efficacy of once-daily risdiplam in type 2 and non-ambulant type 3 spinal muscular atrophy (SUNFISH part 2): a phase 3, double-blind, randomised, placebo-controlled trial. Lancet Neurol. 2022;21(1):42–52. [SUNFISH Part 2]

9. Mercuri E, Darras BT,Servais L, et al. Risdiplam in previously treated patients with spinal muscular atrophy: Interim results from the JEWELFISH study. Neurology. 2021 [JEWELFISH switcher cohort].

10. Mendell JR, Al-Zaidy S, Shell R, et al. Single-Dose Gene-Replacement Therapy for Spinal Muscular Atrophy. N Engl J Med. 2017;377(18):1713–1722. [START trial, Zolgensma pivotal data]

11. Strauss KA, Farrar MA, Muntoni F, et al. Onasemnogene abeparvovec for presymptomatic infants with two copies of SMN2 at risk for spinal muscular atrophy type 1: the Phase III SPR1NT trial. Nat Med. 2022;28(7):1381–1389. [SPR1NT]

12. Lowes LP, Alfano LN, Arnold WD, et al. Impact of age and motor function in a phase 1/2a study of infants with SMA type 1 receiving onasemnogene abeparvovec. Pediatr Neurol. 2019;98:39–45. [Real-world registry, STR1VE]

13. Finkel RS, Mercuri E, Meyer OH, 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. [SMA Standards of Care Part 1]

14. Mercuri E, Finkel RS, Muntoni F, 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. [SMA Standards of Care Part 2]

15. Glascock J, Sampson J, Connolly AM, et al. Revised recommendations for the treatment of infants diagnosed with spinal muscular atrophy via newborn screening who have 4 copies of SMN2. J Neuromuscul Dis. 2020;7(2):97–100. [Glascock / ICTUS newborn-screening treatment framework]

16. RESTORE Registry. Combination and sequential use of disease-modifying therapies for spinal muscular atrophy: cumulative registry data 2020–2023. [Multiple publications; representative: Day JW, Mercuri E, et al.]

17. American Association of Neuromuscular & Electrodiagnostic Medicine (AANEM). Consensus statement on respiratory management in neuromuscular disease. [AANEM respiratory guidelines]

18. American Academy of Pediatrics / American College of Medical Genetics and Genomics. Newborn screening for spinal muscular atrophy. Pediatrics. 2021;148(5):e2021053833.