Association between the SMN2 gene copy number and clinical characteristics of patients with spinal muscular atrophy with homozygous deletion of exon 7 of the SMN1 gene
Background/Aim. Spinal muscular atrophy (SMA) is an autosomal recessive disease characterized by degeneration of alpha motor neurons in the spinal cord and the medulla oblongata, causing progressive muscle weakness and atrophy. The aim of this study was to determine association between the...
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| Main Authors: | , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Ministry of Defence of the Republic of Serbia, University of Defence, Belgrade
2015-01-01
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| Series: | Vojnosanitetski Pregled |
| Subjects: | |
| Online Access: | http://www.doiserbia.nb.rs/img/doi/0042-8450/2015/0042-84501500072Z.pdf |
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| Summary: | Background/Aim. Spinal muscular atrophy (SMA) is an autosomal recessive
disease characterized by degeneration of alpha motor neurons in the spinal
cord and the medulla oblongata, causing progressive muscle weakness and
atrophy. The aim of this study was to determine association between the SMN2
gene copy number and disease phenotype in Serbian patients with SMA with
homozygous deletion of exon 7 of the SMN1 gene. Methods. The patients were
identified using regional Serbian hospital databases. Investigated clinical
characteristics of the disease were: patients’ gender, age at disease onset,
achieved and current developmental milestones, disease duration, current
age, and the presence of the spinal deformities and joint contractures. The
number of SMN1 and SMN2 gene copies was determined using real-time
polymerase chain reaction (PCR). Results. Among 43 identified patients, 37
(86.0%) showed homozygous deletion of SMN1 exon 7. One (2.7%) of 37 patients
had SMA type I with 3 SMN2 copies, 11 (29.7%) patients had SMA type II with
3.1 ± 0.7 copies, 17 (45.9%) patients had SMA type III with 3.7 ± 0.9
copies, while 8 (21.6%) patients had SMA type IV with 4.2 ± 0.9 copies.
There was a progressive increase in the SMN2 gene copy number from type II
towards type IV (p < 0.05). A higher SMN2 gene copy number was associated
with better current motor performance (p < 0.05). Conclusion. In the Serbian
patients with SMA, a higher SMN2 gene copy number correlated with less
severe disease phenotype. A possible effect of other phenotype modifiers
should not be neglected. |
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| ISSN: | 0042-8450 2406-0720 |