OBJECTIVES: To study the natural history of spinal muscular atrophy (SMA) in Chongqing and surrounding areas, China, and to provide a clinical basis for comprehensive management and gene modification therapy for SMA. METHODS: A retrospective analysis was performed on the medical data and survival status of 117 children with SMA. RESULTS: Of the 117 children, 62 (53.0%) had type 1 SMA, 45 (38.5%) had type 2 SMA, and 10 (8.5%) had type 3 SMA, with a median age of onset of 2 months, 10 months, and 15 months, respectively. Compared with the children with type 2 SMA or type 3 SMA, the children with type 1 SMA had significantly shorter time to onset, consultation, and confirmed diagnosis ( CONCLUSIONS There are differences in clinical manifestations and survival rates among children with different types of SMA. The children with type 1 SMA have a low survival rate, and those with type 2 SMA may have non-linear regression of motor ability. Early identification and management of SMA should be performed in clinical practice.
Child ; Homozygote ; Humans ; Infant ; Muscular Atrophy, Spinal/genetics* ; Retrospective Studies ; Sequence Deletion ; Spinal Muscular Atrophies of Childhood/genetics*

OBJECTIVETo establish a means for prenatal prediction of spinal muscular atrophy (SMA) through survival motor neuron (SMN) gene deletion analysis and genetic counseling in families with a child affected with SMA.

METHODSGenetic analysis for prenatal prediction of Werdnig-Hoffmann disease was performed in a at risk Chinese family by polymerase chain reaction (PCR)-single-strand conformation polymorphism (SSCP) in SMN gene exons 7 and 8.

RESULTSThe pregnancy was positive for the homozygous deletion of the SMN gene, thus the fetus was diagnosed as being affected and the pregnancy was terminated.

CONCLUSIONThis approach is fast and reliable for DNA-based prenatal diagnosis of Werdnig-Hoffmann disease.

China ; Female ; Fetal Diseases ; diagnosis ; Gene Deletion ; Genetic Counseling ; Humans ; Pregnancy ; Prenatal Diagnosis ; Spinal Muscular Atrophies of Childhood ; diagnosis ; genetics

OBJECTIVETo explore the genotypic and clinical features and laboratory examinations of spinal muscular atrophy type 3 (SMA III).

METHODSResults of genetic testing and laboratory exams of 18 SMA III patients were collected and analyzed.

RESULTSThe average age of onset of patients was 6.1 years, with the course of disease lasting from 13 months to 28 years. All patients became symptomatic with lower extremity muscle weakness. The symptoms gradually aggregated, with proximal lower limb muscle becoming atrophic and proximal upper limb muscle becoming weak. Genetic testing indicated that all subjects possessed homozygous deletions of SMN1 gene. Electromyography (EMG) of 15 subjects indicated neurogenic damage. Whilst younger patients had normal level of creatine kinase (CK), elder patients had higher level of CK, though no linear correlation was found.

CONCLUSIONFull understanding of Clinical, especially the growth features of SMA III, in combination with genetic testing, can facilitate diagnosis and early intervention of the disease.

Adolescent ; Adult ; Age of Onset ; Child ; Child, Preschool ; Female ; Genetic Testing ; methods ; Genotype ; Humans ; Male ; Spinal Muscular Atrophies of Childhood ; diagnosis ; genetics ; pathology ; Survival of Motor Neuron 1 Protein ; genetics

OBJECTIVESpinal muscular atrophy (SMA) is a common autosomal recessive disorder and represents one of the most common genetic causes of death in childhood. The last 10 years have seen major advances in the field of SMA, but no curative treatment is available so far. This study aimed to analyze the clinical characteristics of SMA, improve the clinical diagnosis of SMA, and explore the importance of gene diagnosis and prenatal diagnosis of SMA by gene deletion analysis.

METHODSTotally 83 cases with SMA including 55 males and 28 females were enrolled in this study. The age was between 1 day and 14 years (average 23.7 months). The clinical characteristics and changes of electromyography were assessed in all cases. The muscular biopsy was performed in 2 of 83 cases. The deletion of survival of motor neuron gene (SMN) was detected by PCR and restriction endonuclease spectrum analysis in 13 of 83 cases.

RESULTSThe 83 cases were subdivided into three clinical groups based on age of onset of symptom, age at death and achievement of certain motor milestone, 60 cases with type I, 19 cases with type II and 4 cases with type III. They were all characterized by symmetric muscle weakness (more proximal than distal) associated with atrophy, absence or marked decrease of deep tendon reflexes. Electromyographic studies showed a pattern of denervation with neither sensory involvement nor marked decrease of motor nerve conduction velocities in all cases. Muscle biopsy provided evidence of skeletal muscle denervation with groups of atrophy in 2 cases. The SMN detection revealed deletion of exon 7 and exon 8 in 11 of 13 cases, only lacking exon 7 in 1 of 13 cases and lacking exon 8 in 1 of 13 cases.

CONCLUSIONSMA is characterized by degeneration of lower motor neuron associated with muscle paralysis and atrophy. The definite diagnosis of SMA will rely on the typical clinical characteristics, changes of electromyogram and muscle biopsy and gene deletion analysis. Gene diagnosis of SMA can provide a basis for prenatal diagnosis which is of great importance in preventing SMA.

Adolescent ; Biopsy ; Child ; Child, Preschool ; Electromyography ; Female ; Humans ; Infant ; Infant, Newborn ; Male ; Muscle, Skeletal ; pathology ; Prenatal Diagnosis ; Spinal Muscular Atrophies of Childhood ; diagnosis ; genetics

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 (NAIP) 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 SMN1 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 NAIP deletion. The findings of homozygous deletions of exon 7 and/or exon 8 of SMN1 gene confirmed the diagnosis of SMA, and suggested that the deletion of SMN1 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 SMA1. 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.
Child ; Child, Preschool ; China ; epidemiology ; Female ; Gene Deletion ; Genetic Predisposition to Disease ; epidemiology ; genetics ; Humans ; Incidence ; Infant ; Male ; Neuronal Apoptosis-Inhibitory Protein ; genetics ; Polymorphism, Single Nucleotide ; genetics ; Spinal Muscular Atrophies of Childhood ; epidemiology ; genetics ; Survival of Motor Neuron 1 Protein ; genetics

Chromatography, High Pressure Liquid ; methods ; Cyclic AMP Response Element-Binding Protein ; genetics ; Female ; Humans ; Male ; Nerve Tissue Proteins ; genetics ; Prenatal Diagnosis ; methods ; RNA-Binding Proteins ; genetics ; SMN Complex Proteins ; Sequence Analysis, DNA ; Spinal Muscular Atrophies of Childhood ; diagnosis ; genetics

OBJECTIVESpinal muscular atrophy (SMA) is an autosomal recessive disorder that results in symmetrical muscle weakness and wasting due to degeneration of the anterior horns of the spinal cord. The clinical picture of SMA is variable and childhood SMA has been classified into 3 types on the basis of the age of onset and clinical course. The survival motor neuron (SMN) gene was mapped to chromosome 5q13. The SMN1 gene has been recognized to be responsible for SMA because of homozygous deletions or intragenic mutations in SMN1 results in childhood onset of SMA. The main objective of this study was to determine the deletion frequency of SMN1 gene and to apply gene analysis in children patients with SMA.

METHODSThe SMA patients were diagnosed and clinically typed according to the international diagnostic criteria, following up cases, and gene analysis. The PCR enzyme assay was used to detect the homozygous deletion of SMN1 gene in SMA patients. A dosage assay that combined multiplexed allele-specific PCR and DHPLC was used to determine the copy numbers of the SMN1 and SMN2 and detect SMN1 heterozygous deletion.

RESULTS(1) A total of 267 patients with SMA were diagnosed from 338 suspicious cases and 143, 82, and 42 cases were typed as types I, II, and III, with the percentages of 53.6% (143/267), 30.7% (82/267) and 15.7% (42/267), respectively. (2) Results of the present study showed that 68.5% (183/267) of SMA patients had homozygous deletions of exons 7 and 8 of SMN1 gene and 12.7% (34/267) had homozygous deletions of only exon 7 of SMN1 gene. The SMN1 heterozygous deletion was confirmed in 12.4% (33/267) of SMA patients. Non-deletion SMA patients accounted for 6.4%(17/267). The homozygous deletions of only exon 8 of SMN1 gene could not be detected. (3) The rates of homozygous or heterozygous deletion in types I and II were very similar. The rate of homozygous deletion was lower in type III than that in type I or II and rate of heterozygous deletion of type III was higher than that in types I or II.

CONCLUSION(1) The frequency and pattern of deletions in the Chinese children patients with SMA are significantly different from that observed in Caucasians populations. Further gene characterization and subtle mutations within the SMN1 gene need to be studied in order to define the molecular basis of SMA in the Chinese population. (2) The gene diagnosis is a special and non invasive method as compared with other methods. A total of 80% patients can be diagnosed through the analysis of the homozygous deletion of SMN1 gene. (3) The clinical diagnosis and gene detection need to be studied in future for the SMA patients with type III.

Adolescent ; Asian Continental Ancestry Group ; genetics ; Child ; Child, Preschool ; European Continental Ancestry Group ; genetics ; Exons ; Female ; Gene Deletion ; Humans ; Infant ; Male ; Spinal Muscular Atrophies of Childhood ; diagnosis ; genetics ; Survival of Motor Neuron 1 Protein ; genetics

OBJECTIVETo assess the association of copy number variations of SMN1, SMN2, NAIP, GTF2H2 and H4F5 genes with clinical classification of spinal muscular atrophy in children, and determine the copy number of the SMN gene among pregnant women. A carrier screening was also performed in Sichuan province.

METHODSThe copy number variations of the above genes among 53 confirmed SMA patients were determined with MLPA technique. The copy number variations were analyzed by the Fisher's exact test. Deletion of exon 7 in the SMN1 gene was screened with denaturing high performance liquid chromatography (DHPLC) for 427 pregnant women.

RESULTSAmong the 53 cases of type I, II, and III SMA patients, the rate of homozygous deletion of both exons 7 and 8 of the SMN1 gene were 100%, 94.44% and 87.50%, respectively, whereas those of homozygous deletion of exon 7 of SMN1 gene were 0, 5.56%, and 12.50%, respectively. The patients with 1, 2, 3, and 4 copies of exon 7 of the SMN2 gene were 11.32%, 67.92%, 13.21% and 7.55%, respectively. The patients with 0, 1, and 2 copies of exon 5 of NAIP gene were 11.32%, 62.26%, and 26.42%, respectively. No deletion was detected in GTF2H2 or H4F5 genes. The heterozygous loss rate of exon 7 in SMN gene in the pregnant women population of Sichuan region was approximately 2.11%.

CONCLUSIONCopy number variations of SMN2 and NAIP genes in patients are related to SMA clinical types (P < 0.05). In contrast, there was no relationship between SMA clinical types and deletion of exons 7 and 8 in the SMN1 gene (P > 0.05). Analysis of copy number change in SMN1 gene can assist SMA carrier screening. However, when the general population without SMA family history is screened for disease-causing genes, it should be noted that the type "2+0" carriers may affect the screening result, and the result should be interpreted with caution.

Adolescent ; Child ; Child, Preschool ; DNA Copy Number Variations ; Female ; Genetic Carrier Screening ; Humans ; Infant ; Male ; Neuronal Apoptosis-Inhibitory Protein ; genetics ; Spinal Muscular Atrophies of Childhood ; genetics ; Survival of Motor Neuron 1 Protein ; genetics

OBJECTIVETo perform mutation analysis and describe the genotype of the SMN gene in a patient with spinal muscular atrophy (SMA) and his family.

METHODSDeletion analysis of the SMN1 exon 7 by conventional PCR-restriction fragment length polymorphism (RFLP) and allele-specific PCR, and gene dosage of SMN1 and SMN2 by multiplex ligation-dependent probe amplification (MLPA) were performed for the patient and his parents; reverse transcriptase (RT)-PCR and sequencing were performed for the patient. To determine whether the SMN variant was exclusive to transcripts derived from SMN1, the RT-PCR product of the patient was subcloned and multiple clones were sequenced directly; PCR of SMN exon 5 from the genomic DNA of the parents and direct sequencing were performed to confirm the mutation.

RESULTSIn SMN1 exon 7 deletion analysis, no homozygous deletion of the SMN1 was observed in the family; the gene dosage analysis by MLPA showed that the patient had 1 copy of SMN1 and 1 copy of SMN2 his father had 2 copies of SMN1 and 2 copies of SMN2, and his mother had 1 copy of SMN1 and no SMN2. A previously unreported missense mutation of S230L was identified from the patient and this mutation was also found in his father.

CONCLUSIONA novel missense mutation of S230L was identified in the SMA family and the genotype of the family members were investigated.

Base Sequence ; Child, Preschool ; DNA Mutational Analysis ; Exons ; genetics ; Humans ; Male ; Molecular Sequence Data ; Muscular Atrophy, Spinal ; genetics ; Reverse Transcriptase Polymerase Chain Reaction ; SMN Complex Proteins ; genetics ; Spinal Muscular Atrophies of Childhood ; genetics ; Survival of Motor Neuron 1 Protein ; genetics ; snRNP Core Proteins ; genetics

OBJECTIVETo establish an effective testing system for gene diagnosis, carrier detection and prenatal diagnosis for spinal muscular atrophy (SMA).

METHODSTwenty-six patients with SMA were directly tested with PCR-RFLP for exon 7 deletion in the SMN1 gene. Carrier detection was carried out with multi-PCR-DHPLC. Amniotic fluid was taken at the middle stage of gestation from pregnant women who had given birth to affected children.

RESULTSTwenty-five out of 26 patients were diagnosed as having SMN1 gene deletion. Fifty-two of their parents were found to be carriers of exon 7 deletion. Eight of 20 fetuses were diagnosed as having SMN1 gene deletion by PCR-RFLP.

CONCLUSIONPCR-RFLP and multi-PCR-DHPLC techniques can provide rapid diagnosis for exon 7 deletion detection and carrier detection. PCR-RFLP may also be adapted for prenatal gene diagnosis of exon 7 deletion in SMN1 gene.

Child ; Exons ; genetics ; Female ; Gene Deletion ; Genetic Counseling ; Humans ; Male ; Muscular Atrophy, Spinal ; diagnosis ; genetics ; Polymerase Chain Reaction ; Polymorphism, Restriction Fragment Length ; Pregnancy ; Prenatal Diagnosis ; SMN Complex Proteins ; genetics ; Spinal Muscular Atrophies of Childhood ; diagnosis ; genetics ; Survival of Motor Neuron 1 Protein ; genetics