I'm just going to post this information here in case it should help someone in the future. I have no idea what it means to me yet.

Whole exome testing turned up a genetic variant I didn't know I had from 23andme testing. The SNP was tested on 23andme , but I don't think they reported on it. It's estimated the variant is found in 1 out of 120 people.

BTD: c.1330G>C* rs13078881

rs1378881 - SNPedia

Babies born with two copies of this variant are profoundly deficient in an enzyme called biotinidase, and are at high risk of very serious, and possibly fatal, neurologic and metabolic problems. Testing for biotinidase levels is now part of "New Baby Screening," and the good news is that is very easily treatable with a therapeutic dose of biotin. They have to take it for the rest of their lives, but treatment is that simple.

Biotinidase is the enzyme responsible for allowing your body to make use of biotin which is amply found in food. Without the enzyme, however, your body can't make use of the essential vitamin. Free biotin found in supplements is the replacement.

One of the foremost researchers of biotinidase is Dr. Barry Wolf, a now non-treating pediatrician in Detroit. He's still an active researcher, though, and is very involved in the biotinidase deficiency community.

I found Dr. Wolf's email on a research report and emailed him never expecting to hear back. I was just asking if he thought there was any possibility my problems could be related. He emailed me back within a couple of hours, and called me the next morning. (I nearly fell out of my chair just having a doctor express interest.)

Long story short, he told me to go to my doctor, and get my biotinidase levels tested. That's only way to really know what's going on as they've identified many more BTD variants that can play a role. My doctor was happy to oblige with the test, although she said she'd be totally unable to help with results as she'd never even heard of biotinidase.

My results came in today. In a reference range of 4.8 to 12.0, I was a 4.9...on the low end of normal. Dr. Wolf had asked me to email him the results, which I've just done. I'm hoping to hear back and see if he has any thoughts.

Based on what I've read, you have to have biotinidase level of 30% mean normal or less before they say you should supplement. Apparently being 69% below normal isn't an issue. ? Needless to say I'm supplementing already, but without dramatic effect.

Anyway, here's one of the best "mostly understandable English" explanations of the disorder I've found. Beyond a tie to neurological problems, what makes it so interesting to me is its role in gluconeogenesis as I have reactive hypoglycemia on top of the neuropathy.

Biotin-Responsive Disorders - Springer

The only way an adult would know they're a carrier is if they had a deficient and symptomatic child (1 in 120,000 to 1 in 160,000), or they had a genetic test like I did. I have to wonder how much research has been done on people with my biotinidase levels.