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Spinal muscular atrophy (SMA) is an autosomal recessive genetic disorder caused by survival motor neuron (SMN) protein deficiency leading the loss of motor neurons in the anterior horns of the spinal cord and brainstem. More than 95% of SMA patients are attributed to the homozygous deletion of survival motor neuron 1 (SMN1) gene, and approximately 5% are caused by compound heterozygous with a SMN1 deletion and a subtle mutation. Here, we identified a rare variant c.835-5T>G in intron 6 of SMN1 in a patient affected with type I SMA. We analyzed the functional consequences of this mutation on mRNA splicing in vitro. After transfecting pCI-SMN1, pCI-SMN2, and pCI-SMN1 c.835-5T>G minigenes into HEK293, Neuro-2a, and SHSY5Y cells, reverse transcription polymerase chain reaction (RT-PCR) was performed to compare the splicing effects of these minigenes. Finally, we found that this mutation resulted in the skipping of exon 7 in SMN1, which confirmed the genetic diagnosis of SMA.
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http://dx.doi.org/10.1007/s12031-018-1079-1 | DOI Listing |
Neurol Genet
October 2025
Neuromuscular and Rare Diseases Unit, IRCCS Fondazione Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy.
Background And Objectives: Spinal muscular atrophy 5q (SMA) is a motor neuron disorder caused by recessive pathogenic variants in the gene, which encodes the survival motor neuron (SMN) protein. While the majority of patients with SMA exhibit homozygous deletions in , a minority (2%-5%) of patients with SMA harbor an deletion plus a single nucleotide variant on the second allele, which can be identified through direct gene sequencing. The comprehensive characterization of patients with SMA is increasingly crucial considering emerging therapies and newborn screening initiatives.
View Article and Find Full Text PDFInt J Mol Sci
August 2025
Research Centre for Medical Genetics, Moskvorechie Str., 1, 115522 Moscow, Russia.
Since 2023, the Russian Federation (RF) has implemented an expanded newborn screening (NBS) program for 36 hereditary disorders, which now includes 5q spinal muscular atrophy (5q SMA). As a result of newborn screening for 5q SMA conducted in the RF during 2023-2024, 288 newborns with a homozygous deletion of exon 7 in the gene were identified by molecular genetic methods. The overall observed incidence of 5q SMA was 1 in 8439 newborns, which does not significantly differ from the expected incidence of 1 in 7953 newborns, established by previous pilot screening projects ( > 0.
View Article and Find Full Text PDFInt J Neonatal Screen
August 2025
CEINGE Advanced Biotechnologies Franco Salvatore, s.c.a r.l., 80145 Naples, Italy.
Three targeted therapies are currently available for spinal muscular atrophy (SMA), which have dramatically changed the natural history of this severe and potentially fatal disease. More than 95% of SMA cases have a homozygous deletion of exon 7 of the gene. Disease expression mainly depends on the copy number of , a hypomorphic copy of .
View Article and Find Full Text PDFClin Chem Lab Med
August 2025
Department of Medical Genetics, School of Basic Medical Sciences, 70570 Southern Medical University, Guangzhou, China.
Objectives: Spinal muscular atrophy (SMA) is a severe inherited neuromuscular disorder with a high carrier frequency and incidence rate. An accurate molecular method for genes is crucial in carrier screening, clinical diagnosis, outcome assessment and precision therapies.
Methods: Comprehensively using the multiplex allele specific PCR (mASPCR) and capillary electrophoresis (CE), a novel single tube assay was developed to simultaneously determine the copy number of // genes and five common loss-of-function variants in .
Ann Indian Acad Neurol
July 2025
Pediatric Neurology Unit, Department of Pediatrics, Post Graduate Institute of Medical Education and Research, Chandigarh, India.
Background And Objectives: The clinical spectrum of spinal muscular atrophy (SMA) is heterogenous and depends on several factors. This study aimed to investigate the correlation between the motor outcomes and genetic modifiers of SMN1 gene.
Methods: In this cross-sectional study, children with genetically confirmed diagnosis of SMA were enrolled.