very sorry to hear about the breast cancer in your family. I hope she is getting good medical care and advice.
I have worked in biotech for 10 years, and have a PhD in molecular biology and biophysics.
Cancer sequencing is now a reality as technology has really advanced to make this discovery financially practical.
The place that springs to mind is Foundation Medicine
They are CLIA certified (Clinical Laboratory Improvement Amendents), which basically means they can accept actual patient samples for diagnosis, not just for research.
There are other competitors in the sequencing space out there, and you should definitely check out as well.