Unusual presentation of PYGM gene mutation as late-onset McArdle disease with camptocormia: a case report.

BACKGROUND: Glycogen storage disease type 5 (McArdle disease) leads to a deficiency in the activity of myophosphorylase resulting in an impaired glucose utilization. The disease can be caused by a variety of mutations in the PYGM gene, and its typical clinical manifestation is muscles weakness within the first three decades of life. CASE PRESENTATION: In this case report we present the diagnostic work-up of a physically active 78-year-old Caucasian patient suffering from a 2-year history of progressive camptocormia including clinical, radiologic, histological, and genetic tests. There was no history of neuro-muscular diseases in the family. Serum CK levels were moderately increased while other blood/urine parameters were normal. Magnetic resonance imaging showed fatty remodeling of the muscles of the back. Histochemical examination of a muscle biopsy revealed the absence of myophosphorylase activity, while gene analysis identified a known early-onset McArdle mutation in the PYGM gene. CONCLUSION: This case highlights that the clinical spectrum of PYGM gene mutation typically manifest during adolescence, but it is also a differential diagnosis in late onset muscle disorders and emphases the investigation of the role of ACE inhibitors in this disease.

Update on Inherited Pediatric Motor Neuron Diseases: Clinical Features and Outcome.

BACKGROUND: Inherited pediatric motor neuron diseases (MNDs) are a group of neurodegenerative disorders characterized by the degeneration of motor neurons in the brain and the spinal cord. These diseases can manifest as early as infancy and originate from inherited pathogenic mutations in known genes. Key clinical features of MNDs include muscle weakness, hypotonia, and atrophy due to the degeneration of lower motor neurons or spasticity, hypertonia, and hyperreflexia caused by upper motor neuron dysfunction. The course of the disease varies among individuals and is influenced by the specific subtype. METHODS: We performed a non-systematic, narrative clinical review, employing a systematic methodology for the literature search and article selection to delineate the features of hereditary pediatric motor neuron diseases. RESULTS: The growing availability of advanced molecular testing, such as whole-exome sequencing (WES) and whole-genome sequencing (WGS), has expanded the range of identified genetic factors. These advancements provide insights into the genetic complexity and underlying mechanisms of these disorders. As more MND-related genes are discovered, the accumulating genetic data will help prioritize promising candidate genes for future research. In some cases, targeted treatments based on specific genetic mechanisms have already emerged, underscoring the critical role of early and timely diagnosis in improving patient outcomes. Common MNDs include amyotrophic lateral sclerosis, spinal muscular atrophy, and bulbar spinal muscular atrophy. CONCLUSION: This narrative clinical review covers the clinical presentation, genetics, molecular features, and pathophysiology of inherited pediatric MNDs.

Acceptability, validity and responsiveness of inertial measurement units for assessing motor recovery after gene therapy in infants with early onset spinal muscular atrophy: a prospective cohort study.

BACKGROUND: Onasemnogene abeparvovec gene replacement therapy (GT) has changed the prognosis of patients with spinal muscular atrophy (SMA) with variable outcome regarding motor development in symptomatic patients. This pilot study evaluates acceptability, validity and clinical relevance of Inertial Measurement Units (IMU) to monitor spontaneous movement recovery in early onset SMA patients after GT. METHODS: Clinical assessments including CHOPINTEND score (the gold standard motor score for infants with SMA) and IMU measurements were performed before (M0) and repeatedly after GT. Inertial data was recorded during a 25-min spontaneous movement task, the child lying on the back, without (10 min) and with a playset (15 min) wearing IMUs. Two commonly used parameters, norm acceleration 95th centile (||A||_95) and counts per minute (||A||_CPM) were computed for each wrist, elbow and foot sensors. RESULTS: 23 SMA-patients were included (mean age at diagnosis 8 months [min 2, max 20], 19 SMA type 1, three type 2 and one presymptomatic) and 104 IMU-measurements were performed, all well accepted by families and 84/104 with a good child participation (evaluated with Brazelton scale). ||A||_95 and ||A||_CPM showed high internal consistency (without versus with a playset) with interclass correlation coefficient for the wrist sensors of 0.88 and 0.85 respectively and for the foot sensors of 0.93 and 0.91 respectively. ||A||_95 and ||A||_CPM were strongly correlated with CHOPINTEND (r for wrist sensors 0.74 and 0.67 respectively and for foot sensors 0.61 and 0.68 respectively, p-values < 0.001). ||A||_95 for the foot, the wrist, the elbow sensors and ||A||_CPM for the foot, the wrist, the elbow sensors increased significantly between baseline and the 12 months follow-up visit (respective p-values: 0.004, < 0.001, < 0.001, 0.006, < 0.001, < 0.001). CONCLUSION: IMUs were well accepted, consistent, concurrently valid, responsive and associated with unaided sitting acquisition especially for the elbow sensors. This study is the first reporting a large set of inertial sensor derived data after GT in SMA patients and paves the way for IMU-based follow-up of SMA patients after treatment.

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.

Thrombospondin-4 as potential cerebrospinal fluid biomarker for therapy response in pediatric spinal muscular atrophy.

BACKGROUND AND PURPOSE: Spinal muscular atrophy (SMA) as the second most common neurodegenerative disorder in childhood is characterized by the deficiency of survival of motor neuron (SMN) protein leading predominantly to degeneration of alpha motor neurons and consequently to progressive muscle weakness and atrophy. Besides some biomarkers like SMN2 copy number therapeutic biomarkers for SMA with known relevance for neuromuscular transmission are lacking. Here, we examined the potential of Thrombospondin-4 (TSP4) to serve as a cerebrospinal fluid (CSF) biomarker, which may also indicate treatment response. METHODS: We used untargeted proteomic analyses to determine biomarkers in CSF samples derived from pediatric pre-symptomatic (n = 6) and symptomatic (n = 4) SMA patients. The identified biomarker TSP4 was then validated in additional 68 CSF samples (9 adult and 24 pediatric SMA patients, 5 adult and 13 pediatric non-disease controls in addition to 17 pediatric disease controls) by enzyme-linked immunosorbent assay (ELISA) as an additional analytical approach. RESULTS: Untargeted proteomic analyses of CSF identified a dysregulation of TSP4 and revealed a difference between pre-symptomatic SMA patients and patients identified after the onset of first symptoms. Subsequent ELISA-analyses showed that TSP4 is decreased in pediatric but not adult SMA patients. CSF of pediatric patients with other neurological disorders demonstrated no alteration of TSP4 levels. Furthermore, CSF TSP4 levels of pediatric SMA patients increased after first dose of Nusinersen. CONCLUSIONS: We found that TSP4 levels are exclusively reduced in CSF of pediatric SMA patients and increase after treatment, leading us to the hypothesis that TSP4 could serve as a CSF biomarker with the potential to monitor treatment response in pediatric SMA patients. Moreover, TSP4 enable to distinguish pre-symptomatic and symptomatic patients suggesting a potential to serve as a stratification marker.

Evaluating the clinical efficacy of a long-read sequencing-based approach for carrier screening of spinal muscular atrophy.

Spinal muscular atrophy (SMA) is the second most common fatal genetic disease in infancy. It is caused by deletion or intragenic pathogenic variants of the causative gene SMN1, which degenerates anterior horn motor neurons and leads to progressive myasthenia and muscle atrophy. Early treatment improves motor function and prognosis in patients with SMA, but drugs are expensive and do not cure the disease. Therefore, carrier screening seems to be the most effective way to prevent SMA birth defects. In this study, we genetically analyzed 1400 samples using multiplex ligation-dependent probe amplification (MLPA) and quantitative polymerase chain reaction (qPCR), and compared the consistency of the results. We randomly selected 44 samples with consistent MLPA and qPCR results for comprehensive SMA analysis (CASMA) using a long-read sequencing (LRS)-based approach. CASMA results showed 100% consistency, visually and intuitively explained the inconsistency between exons 7 and 8 copy numbers detected by MLPA in 13 samples. A total of 16 samples showed inconsistent MLPA and qPCR results for SMN1 exon 7. CASMA was performed on all samples and the results were consistent with those of resampling for MLPA and qPCR detection. CASMA also detected an additional intragenic variant c.-39A>G in a sample with two copies of SMN1 (RT02). Finally, we detected 23 SMA carriers, with an estimated carrier rate of 1/61 in this cohort. In addition, CASMA identified the "2 + 0" carrier status of SMN1 and SMN2 in a family by analyzing the genotypes of only three samples (parents and one sibling). CASMA has great advantages over MLPA and qPCR assays, and could become a powerful technical support for large-scale screening of SMA.

Diagnostic Journey of Korean Patients with Spinal Muscular Atrophy.

PURPOSE: Spinal muscular atrophy (SMA) is an autosomal recessive genetic disease characterized by the loss of motor neurons in the spinal cord and brainstem, leading to muscle atrophy and weakness. To understand the diagnostic process of Korean patients with SMA, we analyzed their clinical characteristics and challenges. MATERIALS AND METHODS: We conducted a retrospective study of 38 patients with SMA (9 type II and 29 type III) between January 2000 and September 2023. Clinical, laboratory, and genetic data were reviewed. RESULTS: The median ages at symptom onset and diagnosis were 3.0 years [interquartile range (IQR): 1.0-7.3 years] and 25.0 years (IQR: 10.5-37.3 years), respectively. The median diagnostic delay was 19.6 years (IQR: 6.4-31.0 years). A significantly longer delay was observed in SMA type III patients (median: 21.0 years, IQR: 11.0-31.0 years) compared to SMA type II patients (median: 3.0 years, IQR: 0.9-21.0 years) (p=0.021). No significant difference was observed in the number of clinic visits before diagnosis between patients with SMA type II (median: 2.0, IQR: 1.0-4.5) and those with type III (median: 2.0, IQR: 2.0-6.0, p=0.282). The number of clinic visits before diagnosis showed no significant association with the age at symptom onset and diagnosis (p=0.998 and 0.291, respectively). CONCLUSION: Our investigation is the first examination of the diagnostic journey of Korean patients with SMA. As treatments for SMA progress, the significance of an accurate diagnosis has increased, highlighting the importance of reviewing the diagnostic advancements made thus far.

Paradoxical metabolic acidosis after vomiting in children with spinal muscular atrophy: A report of 9 patients.

BACKGROUND: Spinal muscular atrophy (SMA) is a hereditary neuromuscular disease that progresses toward restrictive respiratory failure due to muscle paralysis. We observed that SMA patients presented with a specific clinical and laboratory profile, consisting of severe metabolic acidosis following an episode of mild vomiting. This is an unusual, little-known, and life-threatening situation for these patients, as hyperventilation induced by metabolic acidosis can lead to exhaustion and to death by mixed acidosis. OBJECTIVE: The aim of our study was to describe this paradoxical acidosis after vomiting in SMA patients and to discuss the physiological basis of this condition. METHODS: We conducted a retrospective single-center study reviewing the clinical and laboratory data of SMA patients who were hospitalized in the intensive care unit for severe metabolic acidosis after vomiting. RESULTS: Our cohort comprised 11 cases. On arrival, the median pH of the patients was 7.23 with a median bicarbonate concentration of 11.7 mmol/L and almost half of them (45 %) had ketone bodies in the blood and/or urine. The median correction time was 24 h for pH and 48 h for bicarbonate concentrations after receiving intravenous hydration with a glucose solution. CONCLUSIONS: We suggest that SMA patients are particularly sensitive to ketoacidosis induced by fasting, even after a few episodes of mild vomiting. Moreover, they have a low buffering capacity due to their severe amyotrophy, which favors metabolic acidosis. They must be quickly hydrated through a glucose-containing solution to avoid exhaustion, mixed acidosis, and death.

Postnatal management of preterm infants with spinal muscular atrophy: experience from German newborn screening.

BACKGROUND: The introduction of newborn screening (NBS) for spinal muscular atrophy (SMA) has increased the early diagnosis of 5q-associated SMA in presymptomatic and symptomatic preterm infants. National and international recommendations for treating preterms and newborns < 38 weeks of gestational age are unavailable. Our retrospective multicentre study aimed to evaluate the postnatal clinical course of preterm infants with 5q-associated SMA diagnosed since the implementation of NBS in Germany in 2021 and to summarize the German experience regarding the decision-making process for available treatment regimens for preterm infants with ≤ 3 survival of motor neuron 2 (SMN2) copies. RESULTS: Twelve preterm infants with 5q-associated SMA and a mean gestational age of 34.0 weeks (range: 26.1-36.8) and birth weight of 2022 g (range: 645-3370) were reported from 8/20 German SMA NBS follow-up centers using a pseudonymized questionnaire. Confirmatory diagnosis, including SMN2 copy number, was completed on average on postnatal day 13. All patients had a biallelic deletion of exon 7 or exons 7 and 8 of the survival of motor neuron 1 (SMN1) gene, with SMN2 copy numbers of two in 10 patients and three in two patients. The neonatal course was complicated by respiratory distress due to prematurity (n = 2), sepsis (n = 2), and jaundice (n = 2). At birth, 11 preterm infants (91.6%) were presymptomatic. However, the neurological status of one patient deteriorated at five weeks of age (postconceptional age of 41.8 weeks) prior to the start of treatment. Disease-modifying treatments were initiated in all patients at a mean postconceptional age of 38.8 weeks, with the majority receiving onasemnogene abeparvovec (83.3%, including 2 patients with prior risdiplam bridge therapy). Notably, consensus among participating experts from German neuromuscular centers resulted in 83.3% of patients receiving disease-modifying treatment at term. CONCLUSIONS: Premature infants with SMA require interdisciplinary care in close collaboration with the neuromuscular center. SMA NBS facilitates early initiation of disease-modifying therapy, ideally during the presymptomatic phase, which significantly influences the prognosis of the newborn.

A rapid and easy-to-use spinal muscular atrophy screening tool based on primers with high specificity and amplification efficiency for SMN1 combined with single-stranded tag hybridization assay.

Spinal muscular atrophy (SMA) is an intractable neuromuscular disorder primarily caused by homozygous deletions in exon 7 of the SMN1 gene. Early diagnosis and prompt treatment of patients with SMA have a significant impact on prognosis, and several therapies have recently been developed. Current SMA screening tests require a significant turnaround time to identify patients with suspected SMA, due both to the interval between the birth of a newborn and the collection of blood for newborn mass screening and the difficulty in distinguishing between SMN1 and SMN2, a paralog gene that requires testing in specialized laboratories. The aim of this study was therefore to develop a novel SMA screening assay that can be rapidly performed in ordinary hospitals and clinics to overcome these issues. We designed over 100 combinations of forward and reverse primers with 3' ends targeting SMN1-specific sites around exon 7, and evaluated their specificity and amplification efficiency by quantitative PCR to identify the best primer pair. Furthermore, we performed a single-stranded tag hybridization assay after PCR. To evaluate the accuracy and practicality of the newly developed assay, we analyzed saliva specimens from five patients with SMA and two SMA carriers collected in an outpatient clinic and DNA specimens from three patients with SMA and four SMA carriers from a biobank, together with those from healthy individuals. DNA and raw saliva specimens from all patients with SMA demonstrated a biallelic loss of SMN1, whereas those from carriers and healthy individuals did not. The results of 50 independent experiments were consistent for all samples. The assay could be completed within one hour. This simple and convenient new screening tool has the potential to allow patients with SMA to receive disease-modifying therapies within a shorter timeframe.

Emphasis on the importance of comprehensive clinical and genetic analysis - spinal muscular atrophy combined with phenylketonuria: A case report.

RATIONALE: Both spinal muscular atrophy (SMA) and Phenylketonuria (PKU) are caused by biallelic pathogenic mutations. However, there has been no report on case who suffering from both diseases simultaneously. SMA mainly affects the motor function while PKU may have an impact on both the intelligence and motor function. But if only 1 disease is treated while neglecting the other, the treatment effect will be compromised. Here, for the first time, we report a case from China diagnosed with both these diseases and treated properly. PATIENT CONCERNS: A boy was admitted to the Children's Hospital Affiliated to Shandong University (Jinan, China) due to "limb weakness for 19 months" when he was 22 months old. Considering that the child's motor function development is delayed, we made a comprehensive examinations including inherited metabolic diseases and found a significantly increase of phenylalanine concentration in the blood which indicating PKU. Combined with his typical clinical manifestations of SMA, target capture sequencing followed by Sanger sequencing and multiplex ligation-dependent probe amplification (MLPA) technologies were used for genetic confirmation. DIAGNOSES: SMA and PKU was confirmed. INTERVENTIONS: The child was treated with risdiplam and low phenylalanine formula immediately when he was diagnosed with both SMA and PKU. OUTCOMES: The child showed remarkable improvement in motor function and significant decrease of blood phenylalanine concentration after treatment. LESSONS: To our knowledge, this is the first reported case of SMA combined with PKU. This case expands our understanding of diagnosis for synchronous SMA and PKU and highlights the importance of comprehensive examinations and the utilizing of various genetic testing methods to make an accurate diagnosis of genetic diseases, which may help avoiding the progressive damage caused by certain genetic disease with insidious clinical symptoms.

Cost-Effectiveness Analysis of Newborn Screening for Spinal Muscular Atrophy in Italy.

BACKGROUND AND OBJECTIVE: Untreated spinal muscular atrophy (SMA) is the leading genetic cause of death in children younger than 2 years of age. Early detection through newborn screening allows for presymptomatic diagnosis and treatment of SMA. With effective treatments available and reimbursed by the National Health Service, many regions in Italy are implementing newborn screening for SMA. We evaluated the cost effectiveness of universal newborn screening for SMA in Italy. METHODS: A decision-analytic model assessed the cost effectiveness of newborn screening from the National Health Service perspective in 400,000 newborns. Newborn screening enabling early identification and presymptomatic treatment of SMA was compared with no newborn screening, symptomatic diagnosis, and treatment. Transition probabilities between health states were estimated from clinical trial data. Higher-functioning health states were associated with increased survival, higher utility values, and lower costs. Long-term survival and utilities were extrapolated from scientific literature. Health care costs were collected from official Italian sources. A lifetime time horizon was applied, and costs and outcomes were discounted at an annual rate of 3%. Deterministic and probabilistic sensitivity analyses were conducted. RESULTS: Newborn screening followed by presymptomatic treatment yielded 324 incremental life-years, 390 incremental quality-adjusted life-years, and reduced costs by €1,513,375 over a lifetime time horizon compared with no newborn screening. Thus, newborn screening was less costly and more effective than no newborn screening. Newborn screening has a 100% probability of being cost effective, assuming a willingness-to-pay threshold of > €40,000. CONCLUSIONS: Newborn screening followed by presymptomatic SMA treatment is cost effective from the Italian National Health Service perspective.

Machine learning-enhanced electrical impedance myography to diagnose and track spinal muscular atrophy progression.

Objective.To evaluate electrical impedance myography (EIM) in conjunction with machine learning (ML) to detect infantile spinal muscular atrophy (SMA) and disease progression.Approach. Twenty-six infants with SMA and twenty-seven healthy infants had been enrolled and assessed with EIM as part of the NeuroNEXT SMA biomarker study. We applied a variety of modern, supervised ML approaches to this data, first seeking to differentiate healthy from SMA muscle, and then, using the best method, to track SMA progression.Main Results.Several of the ML algorithms worked well, but linear discriminant analysis (LDA) achieved 88.6% accuracy on subject muscles studied. This contrasts with a maximum of 60% accuracy that could be achieved using the single or multifrequency assessment approaches available at the time. LDA scores were also able to track progression effectively, although a multifrequency reactance-based measure also performed very well in this context.Significance.EIM enhanced with ML promises to be effective for providing effective diagnosis and tracking children and adults with SMA treated with currently available therapies. The normative trends identified here may also inform future applications of the technology in very young children. The basic analyses applied here could also likely be applied to other neuromuscular disorders characterized by muscle atrophy.

Camptocormia in a young man with anti-GAD-seropositive stiff-person syndrome.

Stiff-person syndrome (SPS) usually manifests as an autoimmune neuromuscular disorder characterised by pronounced and advancing rigidity, primarily affecting the trunk and proximal muscles. There are various clinical subtypes like classic SPS (truncal stiffness, generalised rigidity and muscle spasms), partial SPS (stiff-limb syndrome) and uncommon forms including progressive encephalomyelitis with rigidity and myoclonus. Camptocormia, defined as forward flexion of the spine in the upright position that disappears in the supine position, without fixed deformity, has been described only in two cases as an initial presentation of Anti glutamic acid decarboxylase (GAD) autoimmunity. We encountered a young male presenting with a progressive forward-leaning posture and involuntary rhythmic movements in the lower limb. Diagnostic workup included MRI, blood routines, autoimmune screening, genetic testing, lumbar puncture and electromyography. Elevated serum anti-GAD antibody levels, inflammatory CSF and certain other clinical features supported the diagnosis of SPS. Treatment involved benzodiazepines, muscle relaxants and immunotherapy with intravenous immunoglobulin. This case underscores the importance of considering immune-mediated causes, such as SPS, in patients presenting with camptocormia.

Health information literacy among children with spinal muscular atrophy and their caregivers.

BACKGROUND: Spinal muscular atrophy (SMA) is an autosomal recessive motor neuron disease that leads to multiple organ dysfunction. The advent of disease-modifying treatments makes the early diagnosis of SMA critical. Health information literacy is vital for obtaining, understanding, screening, and using health information. Considering the importance of early diagnosis and the challenges in obtaining accurate information on patients with SMA, this cross-sectional study assessed health information literacy among children with SMA and their caregivers in China. METHODS: Interviews with the caregivers of 10 patients with SMA were conducted by neurologists specializing in SMA. A questionnaire for evaluating the level of health information literacy was further developed among 145 children with SMA aged 10.0-120.0 months, with the average age of 81.9 months, and their caregivers. Parameters, such as the age at the onset of the first symptom and time from recognition of the first symptom to diagnosis, were examined. Health information literacy was measured using four dimensions: cognition, search, evaluation, and application. RESULTS: The average time from the first symptom to first medical consultation was 4.8 months, and that from the first symptom to diagnosis was 10.8 months. There is a significant delay from the onset of the initial symptoms to a definitive diagnosis. Thirty-five (24%) patients had poor while 26 (18%) had high health information literacy. The overall score for health information literacy was 69; the scores for health information cognition and application were 90 and 84, respectively. The scores for evaluation (61) and search (57) were low. Medical personnel were considered the most professional and credible sources of information. Additionally, search engines and patient organizations were the other two most important sources of health literacy. CONCLUSION: Patients with SMA and their caregivers had low levels of health information literacy. SMA information visibility and standardization need to be improved. Medical personnel with experience in the diagnosis and treatment of SMA and media should aim to share knowledge and increase the quality of life of those with SMA.

Rare Variants of the SMN1 Gene Detected during Neonatal Screening.

During the expanded neonatal screening program conducted in 2023, we analyzed samples obtained from 1,227,130 out of 1,256,187 newborns in the Russian Federation in order to detect 5q spinal muscular atrophy (5q SMA). Within the 253-sample risk group formed based on the results of the first screening stage, 5 samples showed a discrepancy between the examination results obtained via various screening methods and quantitative MLPA (used as reference). The discrepancy between the results was caused by the presence of either a c.835-18C>T intronic variant or a c.842G>C p.(Arg281Thr) missense variant in the SMN1 gene, both of which are located in the region complementary to the sequences of annealing probes for ligation and real-time PCR. Three newborns had the c.835-18C>T variant in a compound heterozygous state with a deletion of exons 7-8 of the SMN1 gene, one newborn with two copies of the SMN1 gene had the same variant in a heterozygous state, and one newborn had both variants-c.835-18C>T and c.842G>C p.(Arg281Thr)-in a compound heterozygous state. Additional examination was carried out for these variants, involving segregation analysis in families, carriage analysis in population cohorts, and RNA analysis. Based on the obtained results, according to the ACMG criteria, the c.835-18C>T intronic variant should be classified as likely benign, and the c.842G>C p.(Arg281Thr) missense substitution as a variant of uncertain clinical significance. All five probands are under dynamic monitoring. No 5q SMA symptoms were detected in these newborns neonatally or during a 1-year follow-up period.

Newborn Screening and Birth Prevalence for Spinal Muscular Atrophy in the US.

This cross-sectional study describes the collection and use of state-provided data on newborn screening for spinal muscular atrophy.