SMN1: Difference between revisions

SMN1
Symbol	SMN1
HGNC ID	11118
Alternative symbols	–
Entrez Gene	6606
OMIM	600354
RefSeq	NM_000344
UniProt	Q16637
Chromosome	5q13.2
Locus supplementary data	–

Latest revision as of 20:42, 30 December 2024

SMN1 (Survival of Motor Neuron 1) is a gene located on chromosome 5 at the 5q13.2 region. It encodes the SMN protein, which is crucial for the survival of motor neurons. Mutations in the SMN1 gene are responsible for spinal muscular atrophy (SMA), a genetic disorder characterized by the loss of motor neurons and progressive muscle wasting.

Function[edit]

The SMN1 gene provides instructions for making the SMN protein, which is part of a complex that is essential for the assembly of small nuclear ribonucleoproteins (snRNPs). These snRNPs are critical components of the spliceosome, a cellular machinery responsible for RNA splicing, a process that removes introns from pre-mRNA.

Clinical Significance[edit]

Mutations in the SMN1 gene lead to a deficiency of the SMN protein, which results in the degeneration of motor neurons in the spinal cord and lower brainstem. This degeneration causes the symptoms of spinal muscular atrophy, which include muscle weakness and atrophy.

Spinal Muscular Atrophy[edit]

Spinal muscular atrophy is classified into several types based on the age of onset and severity of symptoms:

SMA Type 1 (Werdnig-Hoffmann disease) is the most severe form, with symptoms appearing before 6 months of age.
SMA Type 2 presents in children between 6 and 18 months.
SMA Type 3 (Kugelberg-Welander disease) appears after 18 months and is less severe.
SMA Type 4 is the adult-onset form.

Genetic Testing and Diagnosis[edit]

Genetic testing for SMN1 mutations is the primary method for diagnosing spinal muscular atrophy. The most common mutation is a deletion of exon 7 in the SMN1 gene. Carrier testing and prenatal testing are also available for families with a history of SMA.

Treatment[edit]

While there is no cure for SMA, treatments such as nusinersen (Spinraza), gene therapy with onasemnogene abeparvovec (Zolgensma), and risdiplam (Evrysdi) have been developed to increase SMN protein levels and improve motor function.

References[edit]

External Links[edit]

[GeneReviews/NCBI/NIH/UW entry on Spinal Muscular Atrophy]
[OMIM entry on Spinal Muscular Atrophy]

@@ Line 1: / Line 1: @@
-'''SMN1''' (Survival Motor Neuron 1) is a gene that encodes the survival motor neuron protein, which is critical for the maintenance of [[motor neurons]]. Mutations in this gene are associated with [[spinal muscular atrophy]] (SMA), a genetic disorder characterized by progressive muscle weakness and atrophy.
+{{Infobox gene
+| name = SMN1
+| image = <!-- Image removed -->
+| caption = <!-- Caption removed -->
+| HGNCid = 11118
+| symbol = SMN1
+| altSymbols = BCD541, SMA, SMA1, SMA2, SMA3, SMA4, SMN
+| EntrezGene = 6606
+| OMIM = 600354
+| RefSeq = NM_000344
+| UniProt = Q16637
+| chromosome = 5
+| arm = q
+| band = 13.2
+}}
+'''SMN1''' (Survival of Motor Neuron 1) is a [[gene]] located on [[chromosome 5]] at the 5q13.2 region. It encodes the [[SMN protein]], which is crucial for the survival of [[motor neurons]]. Mutations in the SMN1 gene are responsible for [[spinal muscular atrophy]] (SMA), a genetic disorder characterized by the loss of motor neurons and progressive muscle wasting.
 == Function ==
-The SMN1 gene is located on chromosome 5q13.2 and is approximately 20 kilobases in length. It contains nine exons and encodes the 38-kDa SMN protein. The SMN protein is part of a complex that is necessary for the biogenesis of [[Uridine-rich small nuclear ribonucleoproteins|U snRNPs]], which are essential components of the spliceosome, the molecular machinery that processes pre-mRNAs to produce mature [[mRNA]]s.
+The SMN1 gene provides instructions for making the SMN protein, which is part of a complex that is essential for the assembly of [[small nuclear ribonucleoproteins]] (snRNPs). These snRNPs are critical components of the [[spliceosome]], a cellular machinery responsible for [[RNA splicing]], a process that removes [[introns]] from pre-mRNA.
-== Clinical significance ==
+== Clinical Significance ==
-Mutations in the SMN1 gene are the primary cause of spinal muscular atrophy (SMA), a leading genetic cause of infant mortality. SMA is characterized by the degeneration of motor neurons in the [[anterior horn of spinal cord|anterior horn cells]] of the spinal cord, leading to muscle weakness and atrophy. The severity of SMA is inversely correlated with the number of copies of a nearly identical gene, [[SMN2]], which can partially compensate for the loss of SMN1 function.
+Mutations in the SMN1 gene lead to a deficiency of the SMN protein, which results in the degeneration of motor neurons in the [[spinal cord]] and lower brainstem. This degeneration causes the symptoms of spinal muscular atrophy, which include muscle weakness and atrophy.
-== Diagnosis ==
+=== Spinal Muscular Atrophy ===
-Diagnosis of SMA is confirmed by genetic testing, which involves the detection of homozygous deletions or mutations in the SMN1 gene. Prenatal testing is also available for families with a known history of SMA.
+Spinal muscular atrophy is classified into several types based on the age of onset and severity of symptoms:
+* '''SMA Type 1''' (Werdnig-Hoffmann disease) is the most severe form, with symptoms appearing before 6 months of age.
+* '''SMA Type 2''' presents in children between 6 and 18 months.
+* '''SMA Type 3''' (Kugelberg-Welander disease) appears after 18 months and is less severe.
+* '''SMA Type 4''' is the adult-onset form.
+== Genetic Testing and Diagnosis ==
+Genetic testing for SMN1 mutations is the primary method for diagnosing spinal muscular atrophy. The most common mutation is a deletion of exon 7 in the SMN1 gene. Carrier testing and prenatal testing are also available for families with a history of SMA.
 == Treatment ==
-There is currently no cure for SMA. Treatment is supportive and aims to manage symptoms and improve quality of life. In recent years, therapies that target the underlying genetic defect, such as [[Nusinersen]] and [[Onasemnogene abeparvovec]], have shown promise in clinical trials.
+While there is no cure for SMA, treatments such as [[nusinersen]] (Spinraza), [[gene therapy]] with [[onasemnogene abeparvovec]] (Zolgensma), and [[risdiplam]] (Evrysdi) have been developed to increase SMN protein levels and improve motor function.
-[[File:SMN1 gene location on chromosome.png|thumb|right|Location of the SMN1 gene on chromosome 5]]
+== See Also ==
-== See also ==
-* [[Spinal muscular atrophy]]
 * [[SMN2]]
-* [[Motor neuron]]
+* [[Motor neuron disease]]
-* [[Gene therapy]]
+* [[Genetic disorder]]
 == References ==
-<references />
+<references/>
+== External Links ==
+* [GeneReviews/NCBI/NIH/UW entry on Spinal Muscular Atrophy]
+* [OMIM entry on Spinal Muscular Atrophy]
-[[Category:Genes]]
+[[Category:Genes on human chromosome 5]]
-[[Category:Neurogenetics]]
+[[Category:Motor neuron diseases]]
-[[Category:Medical genetics]]
+[[Category:Genetic disorders with OMIM but no gene]]
-{{medicine-stub}}