Diagnosis and clinical management of spinal muscular atrophy

Analysis of spinal muscular atrophy carrier screening results in 32,416 pregnant women and 7,231 prepregnant women

Objectives

Spinal muscular atrophy (SMA) is an autosomal recessive disease that is one of the most common in childhood neuromuscular disorders. Our screenings are more meaningful programs in preventing birth defects, providing a significant resource for healthcare professionals, genetic counselors, and policymakers involved in designing strategies to prevent and manage SMA.

Method

We screened 39,647 participants from 2020 to the present by quantitative real-time PCR, including 7,231 pre-pregnancy participants and 32,416 pregnancy participants, to detect the presence of SMN1 gene EX7 and EX8 deletion in the DNA samples provided by the subjects. To validate the accuracy of our findings, we also utilized the Multiplex Ligation-dependent Probe Amplification (MLPA) to confirm the reliability of screening results obtained by quantitative real-time PCR.

Result

Among the 39,647 participants who were screened, 726 participants were the carriers of SMN1. The overall carrier rate was calculated to be 1.83% (95% confidence interval: 0.86-2.8%). After undergoing screening, a total of 592 pregnancy carriers were provided with genetic counseling and only 503 of their spouses (84.97, 95% confidence interval: 82.09-87.85%) voluntarily underwent SMA screening.

Conclusion

This study provides crucial insights into the prevalence and distribution of SMA carriers among the female population. The identification of 726 asymptomatic carriers highlights the necessity of comprehensive screening programs to identify at-risk individuals and ensure appropriate interventions are in place to minimize the impact of SMA-related conditions.

Lessons from Real Life Experience: Importance of In-House Sequencing and Smart Ratio-Based Real-Time PCR Outperform Multiplex Ligation-Dependent Probe Amplification in Prenatal Diagnosis for Spinal Muscular Atrophy: Bench to Bedside Diagnosis

Spinal muscular atrophy (SMA) is a rare, recessively inherited neurodegenerative disorder caused by the presence of pathogenic variants in the SMN gene. As it is the leading inherited cause of infant mortality, identification of SMN gene pathogenic variant carriers is important for diagnostic purposes with effective genetic counseling. Multiple ligation probe analysis (MLPA), a probe-based method, is considered as the gold standard for SMA carrier analysis. However, MLPA might give false-negative results in cases with variations in the probe-binding regions. Here, we present a case born to consanguineous SMA carrier parents. Prenatal diagnosis with MLPA failed to detect the compound heterozygous mutant state of the proband and she was born unfortunately with SMA phenotype. Further analysis with a real-time polymerase chain reaction kit was able to detect the compound heterozygous state of the patient and was confirmed with targeted next-generation sequencing technology.

[Respiratory physiotherapy in pediatric practice]

Congestion of the upper (URT) and lower respiratory tracts (LRT) is a common symptom in several acute and chronic respiratory diseases that occur in childhood. To eliminate these secretions, airway clearance techniques (ACT) directed to the URT and LRT are frequently prescribed. The rationale for the application of these techniques is the same as in adults, but they need to be adapted to be transposed to children. The physiotherapist will be able to choose among a wide range of techniques, of which the most adequate will depend not only on the age of the child and the indication, but also on the basis of his preferences or habits, as well as those of the child. Upper airway clearance, including nasal irrigation, is now recommended for acute and chronic rhinosinusitis in children. It is also one of the symptomatic treatments recommended for infants with acute bronchiolitis. For LRT clearance, several indications, such as cystic fibrosis, primary ciliary dyskinesia and neuromuscular disease, are now widely advocated. Conversely, other indications, such as for infants with acute viral bronchiolitis, are highly controversial. Thoughtful application of these techniques is lacking in robust and precise tools to objectively assess the presence of bronchial congestion, and to treat it accordingly. Similarly, no precise and reliable evaluation of the effectiveness of these ACTs is available to date. This review is designed to explore the ACTs used by physiotherapists, to provide an overview of their current indications, and to consider complementary approaches.

Quantitative utilization of prior biological knowledge in the Bayesian network modeling of gene expression data

Background

Bayesian Network (BN) is a powerful approach to reconstructing genetic regulatory networks from gene expression data. However, expression data by itself suffers from high noise and lack of power. Incorporating prior biological knowledge can improve the performance. As each type of prior knowledge on its own may be incomplete or limited by quality issues, integrating multiple sources of prior knowledge to utilize their consensus is desirable.

Results

We introduce a new method to incorporate the quantitative information from multiple sources of prior knowledge. It first uses the Naïve Bayesian classifier to assess the likelihood of functional linkage between gene pairs based on prior knowledge. In this study we included cocitation in PubMed and schematic similarity in Gene Ontology annotation. A candidate network edge reservoir is then created in which the copy number of each edge is proportional to the estimated likelihood of linkage between the two corresponding genes. In network simulation the Markov Chain Monte Carlo sampling algorithm is adopted, and samples from this reservoir at each iteration to generate new candidate networks. We evaluated the new algorithm using both simulated and real gene expression data including that from a yeast cell cycle and a mouse pancreas development/growth study. Incorporating prior knowledge led to a ~2 fold increase in the number of known transcription regulations recovered, without significant change in false positive rate. In contrast, without the prior knowledge BN modeling is not always better than a random selection, demonstrating the necessity in network modeling to supplement the gene expression data with additional information.

Conclusion

our new development provides a statistical means to utilize the quantitative information in prior biological knowledge in the BN modeling of gene expression data, which significantly improves the performance.

SMN deficiency disrupts brain development in a mouse model of severe spinal muscular atrophy

Reduced expression of the survival motor neuron (SMN) gene causes the childhood motor neuron disease spinal muscular atrophy (SMA). Low levels of ubiquitously expressed SMN protein result in the degeneration of lower motor neurons, but it remains unclear whether other regions of the nervous system are also affected. Here we show that reduced levels of SMN lead to impaired perinatal brain development in a mouse model of severe SMA. Regionally selective changes in brain morphology were apparent in areas normally associated with higher SMN levels in the healthy postnatal brain, including the hippocampus, and were associated with decreased cell density, reduced cell proliferation and impaired hippocampal neurogenesis. A comparative proteomics analysis of the hippocampus from SMA and wild-type littermate mice revealed widespread modifications in expression levels of proteins regulating cellular proliferation, migration and development when SMN levels were reduced. This study reveals novel roles for SMN protein in brain development and maintenance and provides the first insights into cellular and molecular pathways disrupted in the brain in a severe form of SMA.

Living and ageing with spinal muscular atrophy type 2: observations among an unexplored patient population

OBJECTIVE

To study conditions of living, participation and diagnostic perceptions in a national population of adult persons with spinal muscular atrophy type 2 (SMA 2).

METHODS

A mixed method design combining cross-sectional survey data with personal narratives was chosen. Twenty-nine of 37 patients with SMA 2 aged >or=18 years participated in a semi-structured questionnaire survey and three were selected for in-depth journalistic interviews. Socioeconomic data, activities and personal significance of problems were calculated. Journalistic stories were analysed for constructs of personal diagnostic qualities.

RESULTS

Everyone was actively directing their life despite being heavily dependent. Deterioration of physical abilities was a major concern for women. Seventy-six per cent were single, but stated their quality of life as fine. Narratives of living with SMA 2 were associated with positive characteristics, as opposed to the medical diagnostic wording.

CONCLUSION

Female coping needs more research. Narrative method complements medical knowledge.