MrsD,
I'm trying not to get to excited about this, but...
On whim today, I decided to send Dr. Barry Wolf MD PhD an email. I found his email address on a biotinidase deficiency research report. He's a pediatrician in Detroit, and appears to be a leading researcher on the deficiency. I didn't think the email would ever actually get by an admin assistant, but he got it. I had explained my BTD variant finding and my neuro problems, and just asked if he had any thoughts if there could be a connection. He emailed me back within a couple of hours and asked for my phone number.
I didn't hear from him tonight, but my fingers are crossed.