Objective: Spinal muscular atrophy(SMA), an autosomal recessive neuromuscular degeneration of the anterior horn cells of the spinal cord and brain stem, results in one of the most common diseases with muscle fatigue a...Objective: Spinal muscular atrophy(SMA), an autosomal recessive neuromuscular degeneration of the anterior horn cells of the spinal cord and brain stem, results in one of the most common diseases with muscle fatigue and atrophy. Most SMA cases including all the types are due to the homozygous deletion of at least exon 7 within the survival motor neuron 1 (SMN-1) gene. Although a “golden standard” assay (PCR with mismatch primer followed by enzyme digestion) is very reliable for the identification of homozygous SMN-1 deletion, the carrier detection of heterozygous SMN-1 deletion remains a challenge. Methods: Some PCR-based gene dosage assays or multiplex PCR allow for the determination of the copy number of SMN-1 gene to identify heterozygous deletion, but these procedures are often time consuming and available on a limited clinical basis. Recently developed MLPA (multiplex ligation-dependent probe amplification) is an efficient procedure that can accurately analyze relative quantification to establish the copy number of the SMN gene. We performed a validation for simultaneous detection of homozygous SMN-1 deletions of SMA patients and heterozygous SMN-1 deletions of SMA carriers in a simple assay using a MLPA-SMA assay specific reagent. Results: Six out of 20 patients with SMA were found to have homozygous SMN-1 deletion, confirmed by the PCR/digestion assay. All 4 parents of the children with SMA had heterozygous SMN-1 deletion, confirmed by an independent relative quantitative analysis. Conclusion: MLPA provides a simple, rapid and accurate method of simultaneously detecting homozygous deletions and heterozygous deletions in a single assay for both SMN-1 and SMN-2 genes.展开更多
Spinal muscular atrophy （SMA） is a disorder characterized by degeneration of lower motor neurons and occasionally bulbar motor neurons leading to progressive limb and trunk paralysis as well as muscular atrophy. Thr...Spinal muscular atrophy （SMA） is a disorder characterized by degeneration of lower motor neurons and occasionally bulbar motor neurons leading to progressive limb and trunk paralysis as well as muscular atrophy. Three types of SMA are recognized depending on the age of onset, the maximum muscular activity achieved, and survivorship： SMA1, SMA2, and SMA3. The survival of motor neuron （SMN） gene has been identified as an SMA determining gene, whereas the neuronal apoptosis inhibitory protein （NAlP） gene is considered to be a modifying factor of the severity of SMA. The main objective of this study was to analyze the deletion of SMN1 and NAIP genes in southern Chinese children with SMA. Here, polymerase chain reaction （PCR） combined with restriction fragment length polymorphism （RFLP） was performed to detect the deletion of both exon 7 and exon 8 of SMN1 and exon 5 of NAIP in 62 southern Chinese children with strongly suspected clinical symptoms of SMA. All the 32 SMA1 patients and 76% （13/17） of SMA2 patients showed homozygous deletions for exon 7 and exon 8, and all the 13 SMA3 patients showed single deletion of SMNI exon 7 along with 24% （4/17） of SMA2 patients. Eleven out of 32 （34%） SMA1 patients showed NAIP deletion, and none of SMA2 and SMA3 patients was found to have NA1P deletion. The findings of homozygous deletions ofexon 7 and/or exon 8 ofSMN1 gene confirmed the diagnosis of SMA, and suggested that the deletion ofSMN1 exon 7 is a major cause of SMA in southern Chinese children, and that the NAIP gene may be a modifying factor for disease severity of SMAI. The molecular diagnosis system based on PCR-RFLP analysis can conveniently be applied in the clinical testing, genetic counseling, prenatal diagnosis and preimplantation genetic diagnosis of SMA.展开更多
文摘Objective: Spinal muscular atrophy(SMA), an autosomal recessive neuromuscular degeneration of the anterior horn cells of the spinal cord and brain stem, results in one of the most common diseases with muscle fatigue and atrophy. Most SMA cases including all the types are due to the homozygous deletion of at least exon 7 within the survival motor neuron 1 (SMN-1) gene. Although a “golden standard” assay (PCR with mismatch primer followed by enzyme digestion) is very reliable for the identification of homozygous SMN-1 deletion, the carrier detection of heterozygous SMN-1 deletion remains a challenge. Methods: Some PCR-based gene dosage assays or multiplex PCR allow for the determination of the copy number of SMN-1 gene to identify heterozygous deletion, but these procedures are often time consuming and available on a limited clinical basis. Recently developed MLPA (multiplex ligation-dependent probe amplification) is an efficient procedure that can accurately analyze relative quantification to establish the copy number of the SMN gene. We performed a validation for simultaneous detection of homozygous SMN-1 deletions of SMA patients and heterozygous SMN-1 deletions of SMA carriers in a simple assay using a MLPA-SMA assay specific reagent. Results: Six out of 20 patients with SMA were found to have homozygous SMN-1 deletion, confirmed by the PCR/digestion assay. All 4 parents of the children with SMA had heterozygous SMN-1 deletion, confirmed by an independent relative quantitative analysis. Conclusion: MLPA provides a simple, rapid and accurate method of simultaneously detecting homozygous deletions and heterozygous deletions in a single assay for both SMN-1 and SMN-2 genes.
基金Project supported by the National Natural Science Foundation of China (No. J0710043)the Natural Science Foundation of Zheji-ang Province (No. 2007C33049), China
文摘Spinal muscular atrophy （SMA） is a disorder characterized by degeneration of lower motor neurons and occasionally bulbar motor neurons leading to progressive limb and trunk paralysis as well as muscular atrophy. Three types of SMA are recognized depending on the age of onset, the maximum muscular activity achieved, and survivorship： SMA1, SMA2, and SMA3. The survival of motor neuron （SMN） gene has been identified as an SMA determining gene, whereas the neuronal apoptosis inhibitory protein （NAlP） gene is considered to be a modifying factor of the severity of SMA. The main objective of this study was to analyze the deletion of SMN1 and NAIP genes in southern Chinese children with SMA. Here, polymerase chain reaction （PCR） combined with restriction fragment length polymorphism （RFLP） was performed to detect the deletion of both exon 7 and exon 8 of SMN1 and exon 5 of NAIP in 62 southern Chinese children with strongly suspected clinical symptoms of SMA. All the 32 SMA1 patients and 76% （13/17） of SMA2 patients showed homozygous deletions for exon 7 and exon 8, and all the 13 SMA3 patients showed single deletion of SMNI exon 7 along with 24% （4/17） of SMA2 patients. Eleven out of 32 （34%） SMA1 patients showed NAIP deletion, and none of SMA2 and SMA3 patients was found to have NA1P deletion. The findings of homozygous deletions ofexon 7 and/or exon 8 ofSMN1 gene confirmed the diagnosis of SMA, and suggested that the deletion ofSMN1 exon 7 is a major cause of SMA in southern Chinese children, and that the NAIP gene may be a modifying factor for disease severity of SMAI. The molecular diagnosis system based on PCR-RFLP analysis can conveniently be applied in the clinical testing, genetic counseling, prenatal diagnosis and preimplantation genetic diagnosis of SMA.
