A 3D animation shows the crucial RNA editing step called splicing

A 3D animation shows the crucial RNA editing step called splicing

SMA Science

Spinal Muscular Atrophy (SMA) is an inherited condition. Humans have two closely related versions of the SMN gene, SMN1 and SMN2. SMN1 is fully functional but SMN2 is only partially functional. SMA occurs when an individual inherits two mutated SMN1 genes and the SMN2 gene cannot produce sufficient SMN protein to maintain motor neuron function. To understand the science of SMA, it is important to understand the flow of genetic information: the DNA code is transcribed into RNA, which is then translated into an SMN protein.

Genes and RNA Splicing

In the SMN gene the protein coding information ("exons") are interrupted by non-coding regions ("introns"). The introns need to be edited out of the RNA to produce the final set of instructions for the SMN protein. This process is called "RNA splicing."

  • An animation shows how the DNA genetic code is made into protein
  • A step-by-step animation shows the details of RNA splicing
  • Dr. Roberts describes the flow of information from DNA to RNA to protein
  • Dr. Roberts describes RNA splicing
  • An animation shows the crucial RNA editing step called splicing
  • Dr. Sharp explains the process of RNA splicing

SMA and Splicing

Unlike the SMN1 gene, the SMN2 gene only produces a small amount of functional SMN protein. Incorrect RNA splicing of the SMN2 gene results in a shortened version of the protein, called Delta7, which is not functional.

  • An animation shows how the change in the SMN2 gene produces a different protein through RNA splicing
  • Drs. Sharp and Krainer describe alternative splicing
  • Dr. Krainer explains the connection between SMA and RNA splicing
  • Dr. Sumner explains how SMA is related to changes in the SMN1 and SMN2 genes