Learn about the biology, genetics, and causes of SMA, and how the SMN1 gene, SMN2 gene, and SMN protein affect SMA disease.

Affected individuals with SMA have a homozygous loss of function of the survival motor neuron gene SMN1 on 5q13 but keep the modifying SMN2 gene. The most common mutation causing SMA is a homozygous deletion of the SMN1 exon 7, which can be readily detected and used as a sensitive diagnostic test.

Feb 24, 2000 · SMA is caused by loss of SMN1 because SMN2 cannot fully compensate for loss of SMN1- produced protein. However, when the SMN2 (dosage) copy number is increased, the small amount of full-length transcript generated by SMN2 is often able to produce a milder SMA II or III phenotype.

Jun 30, 2023 · SMA is an inherited disease caused by a mutation in the two survival motor neuron genes, SMN1 and SMN2. SMN genes make SMN proteins, which are necessary for motor neurons to work. Their job is to send signals from the brain to …

However, there are some key differences between these two genes. The SMN1 gene is the primary gene responsible for producing functional SMN protein, while the SMN2 gene is considered a backup or modifier gene.

Feb 18, 2020 · We developed a method that accurately identifies the CN of SMN1 and SMN2 using genome sequencing (GS) data by analyzing read depth and eight informative reference genome differences between...

Mar 21, 2025 · Background The complex 2 Mb survival motor neuron (SMN) locus on chromosome 5q13, including the spinal muscular atrophy (SMA)-causing gene SMN1 and modifier SMN2, remains incompletely resolved due to numerous segmental duplications. Variation in SMN2 copy number, presumably influenced by SMN1 to SMN2 gene conversion, affects disease severity, though SMN2 copy number alone has insufficient ...

Feb 27, 2023 · The SMN1 and SMN2 genes are both essential to the production of the SMN protein, which plays a key role in the development of many human diseases. While SMN1 is a fully functional gene, SMN2 is a much less efficient version, meaning that it produces significantly less SMN protein than SMN

Spinal muscular atrophy (SMA) is one of the major genetic disorders associated with infant mortality. More than 90% cases of SMA result from deletions or mutations of Survival Motor Neuron 1 (SMN1) gene. SMN2, a nearly identical copy of SMN1, does ...

Array dPCR is a practical technique to determine, accurately and reliably, SMN1 and SMN2 CNs from SMA samples as well as identify gene conversion events and partial deletions of SMN1.