eEF1A2 is a protein that is responsible for making all other proteins in the cell. The process of making new proteins is called translation, and eEF1A2 is a translation factor. Unusually for a translation factor, it isn’t found in all cells in the body but is instead confined to nerve and muscle cells. There is another, very similar, factor called eEF1A1 that carries out the same function in all other cell types (lung, liver, kidney and so on). You can see a short video on this here:
The other unusual thing about this translation factor is that it is only present in higher organisms; all vertebrates have it as far as we know (certainly mammals, birds, frogs and fish) but insects, yeast and bacteria for example only have eEF1A1.
Each of the mutations in eEF1A2 that have been found to cause epilepsy, learning difficulties and/or autism change just one of the building blocks (called amino acids) out of nearly 500 that make up the eEF1A2 protein. Each of these building blocks must be really important for the normal function of eEF1A2 in nerve cells.
The picture shows a model of the eEF1A2 molecule printed on a 3D printer. The orange blob is one of the amino acids that has changed in some of the individuals with epilepsy.