SMN1 Gene and Spinal Muscular Atrophy: Mutations and Clinical Trials

The SMN1 gene sits on chromosome 5q13.2, and its full name is survival of motor neuron 1, telomeric. Orphanet links SMN1 to 4 rare conditions and lists variants in the gene as a cause of all of them. Trial Friend's Spinal Muscular Atrophy page lists SMN1 among the genes behind the condition. As of September 29, 2026, 7 recruiting or soon-opening trials on ClinicalTrials.gov name SMN1 as a gene.

Other symbols for SMN1 in gene databases: BCD541, GEMIN1, SMA1, SMA2, SMA3, SMNT, TDRD16A.

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What the SMN1 gene does

SMN1 makes the survival motor neuron protein, called SMN, which is found throughout the body and is highest in the spinal cord. SMN is needed to keep motor neurons, the nerve cells that tell muscles to move, working.

Summarized from the SMN1 page on MedlinePlus Genetics, U.S. National Library of Medicine, checked September 29, 2026.

SMN1 and Spinal Muscular Atrophy

These condition pages list SMN1 among the genes behind the condition, checked against genetics references when each page was written.

Spinal Muscular Atrophy

The condition usually appears only when both copies of the gene carry a disease-causing variant. One variant alone usually means a person is a carrier.

Most cases are a homozygous SMN1 deletion; SMN2 copy number modifies severity and guides treatment decisions.

SMN1 mutation clinical trials

These recruiting or soon-opening trials mention SMN1 as a gene in their title, summary, eligibility rules or keywords. Some want people with a variant in it, and others study it more broadly, which is why each trial's own words are shown. In cancer trials the gene change is usually one found in the tumor rather than one a person inherited.

7 trials, checked September 29, 2026. The list refreshes from ClinicalTrials.gov every few hours.

RecruitingPhase 1, Phase 2NCT05747261
Study of the Safety and Efficacy of an Adeno-Associated Viral Vector Carrying the SMN Gene After a Single Intravenous Administration of Escalating Doses in Children With Spinal Muscular Atrophy (BLUEBELL)
Spinal Muscular Atrophy (SMA)
Why it's listed: “A diagnosis of 5q-SMA (homozygous deletion of exon 7 of the SMN1 gene or heterozygous deletion of exon 7 + confirmed point mutation of the SMN1 gene) and 2 or 3 copies of the…”
RecruitingNCT07332702
Long Read Analysis in Spinal Muscular Atrophy - LOREASI
Spinal Muscular Atrophy (SMA)
Why it's listed: “Spinal Muscular Atrophy (SMA) is a severe neuromuscular disease caused by deletion of the SMN1 gene, with the most severe form leading to death in children without treatment. Genetic counse…”
RecruitingNCT03217578
Neonatal Spinal Muscular Atrophy (SMA) Screening
Spinal Muscular Atrophy
Why it's listed: “…routine newborn screening samples will be used to test if neonates have lost 2 copies of SMN1 gene. If neonates have positive SMA screening test, further confirmation with multiplex ligati…”
RecruitingNCT06562283
Evaluation of the Reproducibility of a Fatigability Test Fitted to Patients With Spinal Muscular Atrophy
Spinal Amyotrophy · Infantile Spinal Muscular Atrophy · Juvenile Spinal Muscular Atrophy
Why it's listed: “…ation of motor neurons in the anterior horn of the spinal cord, due to the absence of the SMN1 gene and the resulting lack of SMN protein. Some patients with particularly severe forms (type…”
RecruitingPhase 3NCT07444476
A Study to Learn About Salanersen's (BIIB115) Effects on Movement and Its Safety in Participants Aged 15 to 60 Years With Spinal Muscular Atrophy (SMA) Who Are Either New to SMA Treatment or Were Previously Treated With Risdiplam
Spinal Muscular Atrophy
Why it's listed: “…usually does not produce enough SMN protein on its own to make up for the changes in the SMN1 gene. Salanersen is a drug designed to help the SMN2 gene to make more working SMN protein.”
RecruitingPhase 3NCT07444450
A Study to Learn About the Safety and Effects of Salanersen (BIIB115) When Given to Babies With Spinal Muscular Atrophy (SMA) Who Were Previously Treated With Onasemnogene Abeparvovec
Muscular Atrophy, Spinal
Why it's listed: “OA works by replacing the missing or abnormal SMN1 gene. Sometimes, OA treatment may not work as well as expected. As a result, researchers are e…”
RecruitingPhase 1, Phase 2NCT07070999
Study of Safety, Tolerability and Efficacy of GB221 in Infants With Spinal Muscular Atrophy Type 1
Spinal Muscular Atrophy Type I
Why it's listed: “GB221 is a gene therapy that delivers a working SMN1 gene to the motor neurons of people with spinal muscular atrophy (SMA) Type 1. This study will…”

All conditions linked to SMN1 gene mutations

Orphanet records how each gene relates to each condition. Orphanet links SMN1 to 4 rare conditions and lists variants in the gene as a cause of all of them.

  • Causes it. Disease-causing variants in this gene are a direct cause of the condition.
Proximal spinal muscular atrophy type 1Causes itTrial Friend pageOrphanet
Proximal spinal muscular atrophy type 2Causes itTrial Friend pageOrphanet
Proximal spinal muscular atrophy type 3Causes itTrial Friend pageOrphanet
Proximal spinal muscular atrophy type 4Causes itTrial Friend pageOrphanet

SMN1 genetic test results and what a variant can mean

Labs sort each variant they find into 5 groups, from pathogenic and likely pathogenic through uncertain significance to likely benign and benign. Only the first 2 are usually treated as the cause of a condition. A variant of uncertain significance, or VUS, is one without enough evidence either way yet, and labs can reclassify it as research builds.

A genetic counselor or your doctor can explain what a specific result means for you and your family. Our genetic testing guide covers the terms, and MedlinePlus Genetics from the National Library of Medicine has a plain-language page on SMN1.

SMN1 gene questions

What does the SMN1 gene do?

SMN1 makes the survival motor neuron protein, called SMN, which is found throughout the body and is highest in the spinal cord. SMN is needed to keep motor neurons, the nerve cells that tell muscles to move, working. This summary follows MedlinePlus Genetics from the U.S. National Library of Medicine.

Are there clinical trials for people with SMN1 gene variants?

As of September 29, 2026, 7 recruiting or soon-opening trials on ClinicalTrials.gov name SMN1 as a gene. Each one is listed on this page with the words from the trial that mention the gene. ClinicalTrials.gov also lists 94 open trials for Spinal Muscular Atrophy, and Match Me on Trial Friend can check those against age, sex, location and treatment history.

What conditions are linked to the SMN1 gene?

Orphanet links SMN1 to 4 rare conditions and lists variants in the gene as a cause of all of them. They include Proximal spinal muscular atrophy type 1, Proximal spinal muscular atrophy type 2, Proximal spinal muscular atrophy type 3 and Proximal spinal muscular atrophy type 4. Orphanet is the European rare disease database run by INSERM in Paris.

How is Spinal Muscular Atrophy inherited?

The inheritance pattern is autosomal recessive. The condition usually appears only when both copies of the gene carry a disease-causing variant. One variant alone usually means a person is a carrier. Most cases are a homozygous SMN1 deletion; SMN2 copy number modifies severity and guides treatment decisions.

What does an SMN1 variant of uncertain significance mean?

A variant of uncertain significance, or VUS, is a change in the gene that labs don't yet have enough evidence to call disease-causing or harmless. It is not used on its own to diagnose a condition, and labs can reclassify it as research builds. A genetic counselor can explain what a specific result means for you and your family.

Sources

  • Gene and condition links from Orphadata (Orphanet, INSERM US14), used under CC BY 4.0, read September 29, 2026.
  • Trials from ClinicalTrials.gov, read September 29, 2026.
  • SMN1 gene, MedlinePlus Genetics, U.S. National Library of Medicine.
  • Inheritance and gene notes from the Trial Friend condition pages above, each checked against genetics references.

Other gene pages

The gene search covers every gene Orphanet links to a rare disease.