Why should a 5q spinal muscular atrophy neonatal screening program be started?

Spinal muscular atrophy (SMA) is a genetic neuromuscular progressive disorder that is currently treatable. The sooner the disease-modifying therapies are started, the better the prognosis. Newborn screening for SMA, which is already performed in many countries, has been scheduled to begin in the near future. The development of a well-organized program is paramount to achieve favorable outcomes for the child who is born with the disease and for the costs involved in health care. We herein present a review paper hoping to point out that SMA neonatal screening is urgent and will not increase the cost of its care.

A atrofia muscular espinhal (AME) é uma doença genética neuromuscular progressiva tratável atualmente. Quanto antes o tratamento com as terapias modificadoras da doença for iniciado, melhor será o prognóstico. A triagem neonatal para a AME, já implementada em vários países, está programada para iniciar no Brasil em um futuro próximo. O desenvolvimento de um programa bem organizado é fundamental para que se alcance um resultado favorável para as crianças que nascem com a doença e para os custos envolvidos nos cuidados de saúde. Apresentamos um artigo de revisão na esperança de enfatizar que a triagem neonatal para a AME é urgente e não aumentará os custos relacionados aos cuidados.

Communicating the diagnosis of spinal muscular atrophy in endogamous vs. non-endogamous regions.

INTRODUCTION: The high prevalence of endogamy, or inbreeding, in northeastern Brazil, is due to historical and cultural factors, with large families living in cities far from the coast and subject to low socioeconomic and infrastructure levels. This breeding practice results in low genetic variability with an increased prevalence of rare autosomal recessive and neurodegenerative diseases, such as spinal muscular atrophy (SMA). OBJECTIVE: Understanding the impact of communicating the diagnosis of SMA on the mental health of patients and their families and the differences between the Northeast (endogamous region) and the other regions of Brazil (non-endogamous ones). METHODS: Cross-sectional study obtained through a structured questionnaire about the moment of receiving the SMA diagnosis, containing the Impact of Event Scale-Revised. RESULTS AND DISCUSSION: The sample consisted of 100 volunteers from all regions of Brazil, 47 patients diagnosed with SMA and 53 family members present at the time of the diagnosis. There was a predominance of females (83%) and homogeneity between the groups for the variables gender, age, color, education, religion, and SMA subtype (1, 2, 3, and 4). The Northeast region, representing 43% of the sample, despite being less economically favored, showed greater satisfaction with medical care and inclusion in health services, with less self-reported psychological trauma and fewer signs of post-traumatic stress disorder (PTSD) related to the moment of receiving the diagnosis. The non-endogamous regions, in turn, reported the presence of strong waves of emotion, sleep problems, feelings of irritability, anger, and the presence of bad thoughts related to this situation. CONCLUSION: The feeling of inclusion in health services and satisfaction with medical care in the endogamous region had a positive impact on the mental health of those involved, reducing psychological trauma and signs of PTSD arising from the communication of the SMA diagnosis.

Integrated Approaches and Practical Recommendations in Patient Care Identified with 5q Spinal Muscular Atrophy through Newborn Screening.

In recent years, significant progress has been made in 5q Spinal Muscular Atrophy therapeutics, emphasizing the importance of early diagnosis and intervention for better clinical outcomes. Characterized by spinal cord motor neuron degeneration, 5q-SMA leads to muscle weakness, swallowing difficulties, respiratory insufficiency, and skeletal deformities. Recognizing the pre-symptomatic phases supported by screening and confirmatory genetic tests is crucial for early diagnosis. This work addresses key considerations in implementing 5q-SMA screening within the Brazilian National Newborn Screening Program and explores Brazil's unique challenges and opportunities, including genetic tests, time-to-patient referral to specialized centers, program follow-up, and treatment algorithms. We aim to guide healthcare professionals and policymakers, facilitating global discussions, including Latin American countries, and knowledge-sharing on this critical subject to improve the care for newborns identified with 5q SMA.

Brazilian version of the Hammersmith Functional Motor Scale Expanded: cross-cultural adaptation and validation.

BACKGROUND: The Hammersmith Functional Motor Scale Expanded (HFMSE) has been widely used to assess the motor function of patients with spinal muscular atrophy (SMA) older than 2 years, with the ability to sit and/or walk. OBJECTIVE: To translate, cross-culturally adapt and validate the HFMSE to Brazilian Portuguese. METHODS: The translation process and cross-cultural adaptation followed international guidelines recommendations. The reliability and applicability of the Brazilian version consisted of the application of the HFMSE (in Brazilian Portuguese) to 20 patients with types 2 and 3 SMA. Two examiners assessed the participants for interrater reliability, through the analysis of Kappa reliability agreement (k) and intraclass correlation coefficient (ICC). RESULTS: The HFMSE was successfully translated and cross culturally adapted to Brazilian Portuguese. Twenty participants with types 2 and 3 SMA were enrolled in the study (type 2 = 6; type 3 = 14). The ICC for the total score showed very high reliability (ICC =1.00), and the reliability of each of the items individually was considered excellent (Kappa > 0.80). CONCLUSION: The Brazilian version of the HFMSE proved to be valid and reliable for the evaluation of SMA patients older than 2 years with the ability to sit and/or walk.

ANTECEDENTES: A Hammersmith Functional Motor Scale Expanded (HFMSE) tem sido amplamente utilizada para avaliar a função motora de pacientes com atrofia muscular espinhal (AME) maiores de dois anos, com capacidade de sentar e/ou andar. OBJETIVO: Traduzir, adaptar transculturalmente e validar a HFMSE para o português brasileiro. MéTODOS: A tradução e a adaptação transcultural seguiram as diretrizes internacionais. A confiabilidade e a aplicabilidade da versão brasileira consistiram na aplicação da HFMSE (em português brasileiro) em 20 pacientes com AME tipos 2 e 3. Dois examinadores avaliaram os participantes quanto à confiabilidade interexaminadores, por meio da análise da concordância de confiabilidade Kappa (k) e do coeficiente de correlação intraclasse (intraclass correlation coefficient [ICC]). RESULTADOS: O processo de tradução e adaptação transcultural da HFMSE para o português brasileiro foi concluído com sucesso. Vinte participantes com AME tipos 2 e 3 foram incluídos no estudo (tipo 2 = 6; tipo 3 = 14). O ICC para o escore total apresentou confiabilidade alta (ICC = 1.00) e a confiabilidade de cada um dos itens individualmente foi considerada excelente (K > 0,80). CONCLUSãO: A HFMSE (PT-BR) mostrou-se válida e confiável para a avaliação de pacientes com AME, com mais de dois anos de idade e com capacidade de sentar-se independentemente e/ou andar.

Consensus from the Brazilian Academy of Neurology for the diagnosis, genetic counseling, and use of disease-modifying therapies in 5q spinal muscular atrophy.

Spinal muscular atrophy linked to chromosome 5 (SMA-5q) is an autosomal recessive genetic disease caused by mutations in the SMN1. SMA-5q is characterized by progressive degeneration of the spinal cord and bulbar motor neurons, causing severe motor and respiratory impairment with reduced survival, especially in its more severe clinical forms. In recent years, highly effective disease-modifying therapies have emerged, either acting by regulating the splicing of exon 7 of the SMN2 gene or adding a copy of the SMN1 gene through gene therapy, providing a drastic change in the natural history of the disease. In this way, developing therapeutic guides and expert consensus becomes essential to direct the use of these therapies in clinical practice. This consensus, prepared by Brazilian experts, aimed to review the main available disease-modifying therapies, critically analyze the results of clinical studies, and provide recommendations for their use in clinical practice for patients with SMA-5q. This consensus also addresses aspects related to diagnosis, genetic counseling, and follow-up of patients under drug treatment. Thus, this consensus provides valuable information regarding the current management of SMA-5q, helping therapeutic decisions in clinical practice and promoting additional gains in outcomes.

Atrofia muscular espinhal ligada ao cromossomo 5 (AME-5q) é uma doença genética de herança autossômica recessiva causada por mutações no gene SMN1. A AME-5q cursa com degeneração progressiva dos motoneurônios medulares e bulbares, acarretando grave comprometimento motor e respiratório com redução da sobrevida, especialmente nas suas formas clínicas mais graves. Nos últimos anos, terapias modificadoras da doença altamente eficazes, ou que atuam regulando o splicing do exon 7 do gene SMN2 ou adicionando uma cópia do gene SMN1 via terapia gênica, têm surgido, proporcionando uma mudança drástica na história natural da doença. Dessa forma, o desenvolvimento de guias terapêuticos e de consensos de especialistas torna-se importante no sentido de direcionar o uso dessas terapias na prática clínica. Este consenso, preparado por especialistas brasileiros, teve como objetivos revisar as principais terapias modificadoras de doença disponíveis, analisar criticamente os resultados dos estudos clínicos dessas terapias e prover recomendações para seu uso na prática clínica para pacientes com AME-5q. Aspectos relativos ao diagnóstico, aconselhamento genético e seguimento dos pacientes em uso das terapias também são abordados nesse consenso. Assim, esse consenso promove valiosas informações a respeito do manejo atual da AME-5q auxiliando decisões terapêuticas na prática clínica e promovendo ganhos adicionais nos desfechos finais.

El difícil camino al diagnóstico del paciente con atrofia muscular espinal / The difficult path to diagnosis of the patient with spinal muscular atrophy

Introducción. Con las nuevas terapias, el diagnóstico temprano de la atrofia muscular espinal (AME) es esencial. El objetivo de este estudio es analizar los distintos componentes que influyen en el retraso diagnóstico. Población y métodos. Se incluyeron pacientes con un diagnóstico molecular de AME tipo I, II y III. Se estudiaron varios parámetros, como la edad al momento de la aparición del primer signo, qué signo fue y el intervalo entre este y el diagnóstico confirmado. Neurólogos especialistas realizaron entrevistas que se complementaron con la revisión de historias clínicas cuando fue necesario. Resultados. Se entrevistaron 112 pacientes. AME I n = 40, AME II n = 48, AME III n = 24. La mediana de edad en meses al momento del reporte del primer signo fue AME I: 1,5 (R 0-7), AME II: 9 (R 2-20), AME III: 18 (R 8-180). Los primeros signos fueron reconocidos por los padres en el 75 % al 85 % de las veces en todos los subtipos. La mediana del tiempo transcurrido entre el primer signo y la primera consulta médica fue menor a un mes en los tres tipos. La mediana de tiempo transcurrido en meses entre el primer signo y el diagnóstico molecular confirmado fue en AME I: 2 (R 0-11), en AME II: 10 (3-46) y en AME III: 31,5 (R 4-288). Conclusiones. Existe un significativo retraso en el diagnóstico de la AME relacionado fundamentalmente a la falta de sospecha clínica. La demora es menor en AME I y mayor en AME III. Otros factores incluyen deficiencias en el sistema de salud.

Introduction. News treatments, make early diagnosis of spinal muscular atrophy (SMA) critical. The objective of this study is to analyze the different factors that influence delay in diagnosis. Population and methods. Patients with a molecular diagnosis of types I, II, and III SMA were included. Several parameters were studied, such as age at onset of first sign, what sign it was, and the time from recognition of first sign to confirmed diagnosis. Neurologists specialized in SMA conducted interviews, supported by the review of medical records when deemed necessary. Results. A total of 112 patients were interviewed. SMA I n = 40, SMA II n = 48, SMA III n = 24. The median age in months at the time of reporting the first sign was SMA I: 1.5 (R: 0­7), SMA II: 9 (R: 2­20), SMA III: 18 (R: 8­180). In all subtypes, first signs were identified by parents from 75% to 85% of the times. The median time from first sign to first medical consultation was less than a month in all 3 types. The median time in months, from first sign to confirmed molecular diagnosis in SMA I was: 2 (R: 0­11), in SMA II: 10 (R: 3­46), in SMA III: 31.5 (R: 4­288). Conclusions. There is a significant delay in SMA diagnosis mainly related to the absence of clinical suspicion. The delay is shorter in SMA I and longer in SMA III. Other factors include deficiencies in the health care system.

Genetic counseling and carrier screening in candidates for gamete donation at a Portuguese center.

OBJECTIVE: Genetic counseling and carrier screening are part of the gamete donation process by healthy individuals. We aim to review the findings of genetic counseling and carrier screening of a cohort of candidates at our public gametes bank. METHODS: Thirty-four male and 64 female candidates had genetic counseling with a medical geneticist before donation. Of these, one female candidate voluntarily dropped-out. Thirty-four males and 63 females performed karyotype and screening for the more common pathogenic variants for CFTR-related cystic fibrosis and spinal muscular atrophy (SMN1) in the Portuguese population. In addition, all females also performed Fragile X expansion screening (FMR1). Thirty candidates with known or assumed African ancestry performed hemoglobinopathies screening. RESULTS: Six candidates were definitely or temporarily withheld from the donation process given their family or personal history that required further investigation. Of 97 candidates tested, 16.5% presented anomalous laboratory results (16/97): ten candidates were carriers for an autosomal recessive disorder - cystic fibrosis (5/97), sickle cell anemia (3/30), and spinal muscular atrophy (2/97). One female was an FMR1 pre-mutation carrier (1/63). One female candidate presented with triple X mosaicism: 47,XXX[2]/46,XX[50]. Two candidates presented with chromosomal instability of unknown origin. In one candidate, a mosaic for the Philadelphia chromosome was detected, revealing the diagnosis of chronic myeloid leukemia. CONCLUSIONS: From a cohort of 97 candidates, 21.7% had a family/personal history or an anomalous laboratory result that required additional genetic counseling, stressing the importance of performing pre-donation genetic counseling in this population.

The difficult path to diagnosis of the patient with spinal muscular atrophy. / El difícil camino al diagnóstico del paciente con atrofia muscular espinal.

Introduction. News treatments, make early diagnosis of spinal muscular atrophy (SMA) critical. The objective of this study is to analyze the different factors that influence delay in diagnosis. Population and methods. Patients with a molecular diagnosis of types I, II, and III SMA were included. Several parameters were studied, such as age at onset of first sign, what sign it was, and the time from recognition of first sign to confirmed diagnosis. Neurologists specialized in SMA conducted interviews, supported by the review of medical records when deemed necessary. Results. A total of 112 patients were interviewed. SMA I n = 40, SMA II n = 48, SMA III n = 24. The median age in months at the time of reporting the first sign was SMA I: 1.5 (R: 0-7), SMA II: 9 (R: 2-20), SMA III: 18 (R: 8-180). In all subtypes, first signs were identified by parents from 75% to 85% of the times. The median time from first sign to first medical consultation was less than a month in all 3 types. The median time in months, from first sign to confirmed molecular diagnosis in SMA I was: 2 (R: 0-11), in SMA II: 10 (R: 3-46), in SMA III: 31.5 (R: 4-288). Conclusions. There is a significant delay in SMA diagnosis mainly related to the absence of clinical suspicion. The delay is shorter in SMA I and longer in SMA III. Other factors include deficiencies in the health care system.

Introducción. Con las nuevas terapias, el diagnóstico temprano de la atrofia muscular espinal (AME) es esencial. El objetivo de este estudio es analizar los distintos componentes que influyen en el retraso diagnóstico. Población y métodos. Se incluyeron pacientes con un diagnóstico molecular de AME tipo I, II y III. Se estudiaron varios parámetros, como la edad al momento de la aparición del primer signo, qué signo fue y el intervalo entre este y el diagnóstico confirmado. Neurólogos especialistas realizaron entrevistas que se complementaron con la revisión de historias clínicas cuando fue necesario. Resultados. Se entrevistaron 112 pacientes. AME I n = 40, AME II n = 48, AME III n = 24. La mediana de edad en meses al momento del reporte del primer signo fue AME I: 1,5 (R 0-7), AME II: 9 (R 2-20), AME III: 18 (R 8-180). Los primeros signos fueron reconocidos por los padres en el 75 % al 85 % de las veces en todos los subtipos. La mediana del tiempo transcurrido entre el primer signo y la primera consulta médica fue menor a un mes en los tres tipos. La mediana de tiempo transcurrido en meses entre el primer signo y el diagnóstico molecular confirmado fue en AME I: 2 (R 0-11), en AME II: 10 (346) y en AME III: 31,5 (R 4-288). Conclusiones. Existe un significativo retraso en el diagnóstico de la AME relacionado fundamentalmente a la falta de sospecha clínica. La demora es menor en AME I y mayor en AME III. Otros factores incluyen deficiencias en el sistema de salud.

Diagnóstico tardío de atrofia muscular espinal en paciente con síndrome de Down / Late diagnosis of spinal muscular atrophy in a patient with Down syndrome

El síndrome de Down (SD) es la anomalía cromosómica más frecuente entre los recién nacidos vivos. La atrofia muscular espinal (AME), por su parte, es una enfermedad neuromuscular caracterizada por la degeneración progresiva de las motoneuronas del asta anterior de la médula espinal que produce atrofia muscular, debilidad y parálisis. Presentamos el caso de una niña de 6 años con síndrome de Down derivada a nuestro centro para estudio por cuadro de debilidad muscular generalizada de evolución crónica con falta de adquisición de la marcha. Realizamos una revisión bibliográfica enfocándonos en el compromiso neurológico esperable en el síndrome de Down, la evolución de los hitos del desarrollo motor grueso estipulado para este grupo de pacientes y en los hallazgos que deben sugerir la presencia de una enfermedad neuromuscular.

A case of a 6-year-old girl with Down's syndrome is presented. She was referred to our center due to a history of generalized muscle weakness of chronic evolution, associated to her inability to walk. Her mother claimed that the girl's muscle weakness always called her attention as well as the difficulties to the development of motor skills shown by her daughter compared to other children, whether they were healthy or with Down's syndrome. There was information in her medical record and physical exam that strongly suggested the possibility of suffering a neuromuscular disorder. We asked for a molecular study that confirmed the spinal muscular atrophy diagnosis. We carried out a bibliographical revision focusing on the expected neurological impairment in Down's syndrome, the retardation of the gross motor skills development determined for this kind of patients and on the findings that must suggest a neuromuscular disorder.

[Late diagnosis of spinal muscular atrophy in a patient with Down syndrome]. / Diagnóstico tardío de atrofia muscular espinal en paciente con síndrome de Down.

A case of a 6-year-old girl with Down's syndrome is presented. She was referred to our center due to a history of generalized muscle weakness of chronic evolution, associated to her inability to walk. Her mother claimed that the girl's muscle weakness always called her attention as well as the difficulties to the development of motor skills shown by her daughter compared to other children, whether they were healthy or with Down's syndrome. There was information in her medical record and physical exam that strongly suggested the possibility of suffering a neuromuscular disorder. We asked for a molecular study that confirmed the spinal muscular atrophy diagnosis. We carried out a bibliographical revision focusing on the expected neurological impairment in Down's syndrome, the retardation of the gross motor skills development determined for this kind of patients and on the findings that must suggest a neuromuscular disorder.

El síndrome de Down (SD) es la anomalía cromosómica más frecuente entre los recién nacidos vivos. La atrofia muscular espinal (AME), por su parte, es una enfermedad neuromuscular caracterizada por la degeneración progresiva de las motoneuronas del asta anterior de la médula espinal que produce atrofia muscular, debilidad y parálisis. Presentamos el caso de una niña de 6 años con síndrome de Down derivada a nuestro centro para estudio por cuadro de debilidad muscular generalizada de evolución crónica con falta de adquisición de la marcha. Realizamos una revisión bibliográfica enfocándonos en el compromiso neurológico esperable en el síndrome de Down, la evolución de los hitos del desarrollo motor grueso estipulado para este grupo de pacientes y en los hallazgos que deben sugerir la presencia de una enfermedad neuromuscular.

Accuracy of muscle fasciculations for the diagnosis of later-onset spinal muscle atrophy.

Diagnosis of later-onset spinal muscular atrophy (SMA) can be challenging. This study aimed to evaluate the diagnostic properties of the detection of muscle fasciculations for SMA diagnosis in adolescents and adults with proximal muscle weakness. A cross-sectional diagnostic accuracy study was performed, in which 10 subjects with SMA (5 with type II and 5 with type III) and 9 subjects with genetic muscle diseases were evaluated by physical examination, muscle ultrasound (MUS) and electromyography (EMG). Inter-rater reliability of MUS was higher than physical examination and in a sensitivity analysis of MUS, all SMA subjects and a single patient with genetic muscle disease presented fasciculations in at least 2 different muscle groups, resulting in a sensitivity of 1 (95% CI: 0.69 to 1) and a specificity of 0.89 (95% CI: 0.52 to 1) for SMA diagnosis. Forty-two percent of evaluated subjects did not agree to perform EMG, limiting this method results. Muscle ultrasound presented the best diagnostic accuracy and physical examination combined with MUS seemed to be a good strategy for screening adolescents and adults with proximal muscle weakness for SMA. These results might improve diagnostic guidelines for later-onset SMA, leading to earlier diagnosis, treatment and specific care.

Cribado neonatal en atrofia muscular espinal: un desafío para cambiar la historia natural / Neonatal screening in spinal muscular atrophy: a challenge to change the natural history

Introducción: la atrofia muscular espinal (AME) es la primera causa de origen genético de muerte en la infancia. En los últimos 20 años han sido excepcionales los avances en el conocimiento de su base genética, de su historia natural y se han desarrollado estándares de cuidado y nuevas terapias. Este veloz aumento del conocimiento ha llevado al desarrollo de terapias eficaces para esta devastadora enfermedad, pero el tiempo son neuronas, y esa frase nos lleva a pensar la importancia del diagnóstico precoz y, por qué no, del diagnóstico presintomático mediante pesquisa neonatal. Métodos: revisión de la bibliografía disponible, a través de búsqueda en PubMed y Google para trabajos no indexados o publicaciones de organismos de Salud. Resultados: varios estudios clínicos han mostrado la mayor eficacia del tratamiento en pacientes presintomáticos, por lo que lograrlo en estos pacientes llevaría a cambiar radicalmente la historia de esta enfermedad. Conclusión: es importante analizar y promover el desarrollo de pilotos para pesquisa neonatal en vistas a lograr experiencia para, a partir de ello, pensar en la posibilidad de incorporarlo a programas nacionales. (AU)

Introduction: spinal muscular atrophy (SMA) is the first cause of genetic origin of death in childhood. Throughout the last 20 years, we have witnessed exceptional advances in the knowledge of its genetic base, the history of its nature and several standards of care and new therapies have been developed. This rapid increase in knowledge has led to the development of effective therapies for this devastating disease. However, time is neurons, and that phrase reminds us of the importance of early diagnosis, and, why not, of pre-symptomatic diagnosis by means of neonatal screening. Methods: review of scientific papers searching in Pubmed or Google for non-indexed articles or publications of Health organisms. Results: several clinical studies have shown the greatest effectiveness of treatment in pre-symptomatic patients, so achieving the same in these patients would result in radically changing the history of this disease. Discussion: it is important to analyze and promote the development of pilots for neonatal screening in order to gain experience, so from there on to be able to think about the possibility of incorporating it into national programs. (AU)

Cost-Effectiveness of Nusinersen and Universal Newborn Screening for Spinal Muscular Atrophy.

OBJECTIVE: To evaluate the cost-effectiveness of nusinersen with and without universal newborn screening for infantile-onset spinal muscular atrophy (SMA). STUDY DESIGN: A Markov model using data from clinical trials with US epidemiologic and cost data was developed. The primary interventions studied were nusinersen treatment in a screening setting, nusinersen treatment in a nonscreening setting, and standard care. Analysis was conducted from a societal perspective. RESULTS: Compared with no screening and no treatment, the incremental cost-effectiveness ratio (ICER) for nusinersen with screening was $330 558 per event-free life year (LY) saved, whereas the ICER for nusinersen treatment without screening was $508 481 per event-free LY saved. For nusinersen with screening to be cost-effective at a willingness-to-pay (WTP) threshold of $50 000 per event-free LY saved, the price would need to be $23 361 per dose, less than one-fifth its current price of $125 000. Preliminary data from the NURTURE trial indicated an 85.7% improvement in expected LYs saved compared with our base results. In probabilistic sensitivity analysis, nusinersen and screening was a preferred strategy 93% of the time at a $500 000 WTP threshold. CONCLUSION: Universal newborn screening for SMA provides improved economic value for payers and patients when nusinersen is available.

Presymptomatic Diagnosis of Spinal Muscular Atrophy Through Newborn Screening.

OBJECTIVE: To demonstrate the feasibility of presymptomatic diagnosis of spinal muscular atrophy (SMA) through newborn screening (NBS). STUDY DESIGN: We performed a screening trial to assess all newborns who underwent routine newborn metabolic screening at the National Taiwan University Hospital newborn screening center between November 2014 and September 2016. A real-time polymerase chain reaction (RT-PCR) genotyping assay for the SMN1/SMN2 intron 7 c.888+100A/G polymorphism was performed to detect homozygous SMN1 deletion using dried blood spot (DBS) samples. Then the exon 7 c.840C>T mutation and SMN2 copy number were determined by both droplet digital PCR (ddPCR) using the original screening DBS and multiplex ligation-dependent probe amplification (MLPA) using a whole blood sample. RESULTS: Of the 120 267 newborns, 15 tested positive according to the RT-PCR assay. The DBS ddPCR assay excluded 8 false-positives, and the other 7 patients were confirmed by the MLPA assay. Inclusion of the second-tier DBS ddPCR screening assay resulted in a positive prediction value of 100%. The incidence of SMA was 1 in 17 181 (95% CI, 1 in 8323 to 1 in 35 468). Two of the 3 patients with 2 copies of SMN2 and all 4 patients with 3 or 4 copies of SMN2 were asymptomatic at the time of diagnosis. Five of the 8 false-positives were caused by intragenic recombination between SMN1 and SMN2. CONCLUSION: Newborn screening can detect patients affected by SMA before symptom onset and enable early therapeutic intervention. A combination of a RT-PCR and a second-tier ddPCR can accurately diagnose SMA from DBS samples with no false-positives. TRIAL REGISTRATION: ClinicalTrials.gov NCT02123186.