We did a genetic test for small number of well known genetic disabilities when she was younger that did not yield a result. Our neurologist then recommended a "whole exome sequencing" a few years later. This is where we found a result.

Insurance is often reluctant to cover this but it's SOMEWHAT affordable (want to say 2-3k with some hospital magic discounts). I can't say it has affected our course of treatment but we were concerned about what other health related issues may be associated with the diagnosis. And it is somewhat promising that a treatment may someday be available.

I would highly recommend pushing for testing. I am told they continually with run your results against know mutations as they find more. So even if you don't get a result today you may someday.