opinion on trying to identify mutations

Hi everyone, Dr. Cohen ordered merrf panel mutation screening for our son. He believed based on muscle biopsy results and maternal history merrf was our diagnosis. He felt running the small panel screening we would be able to identify the point mutation. The screening came back negative for the four he was tested for. My question is this is there really any benefit to identifying the mutation, I know there are so many to test for, that it's a shot in the dark most times. I mean it really would not change treatment...right? I appreciate any input. Is thefinding the mutation most beneficial to being able to help identify the gene in other family members?

Thanks, Carrie