Genetics of Biotin Deficiency

Biotin, also known as vitamin B7 or vitamin H, is a cofactor which aids in the metabolism of fats, carbohydrates, and proteins.  Biotin deficiency due to diet is pretty rare, but eating raw egg whites for an extended period of time can deplete the body of biotin.  Foods that are high in biotin include egg yolks, nuts, meat, and dairy.

The Linus Pauling Institute website has a great in-depth review of biotin that includes information on deficiency symptoms and the function of this vitamin in the body.

Biotinidase Deficiency

Biotinidase is the enzyme that is involved in the extraction of biotin from food and also in the recycling of free biotin that has been used in another reaction in the body.

Profound biotinidase deficiency is defined as having less than 10% of normal enzyme activity, and partial biotinidase deficiency is defined as having between 10% and 30% of normal enzyme activity.

Note that not everyone with a BTD variant is affected by biotinidase deficiency[ref], but for most, a homozygous polymorphism will result in biotinidase deficiency.

So what happens if you are heterozygous for one of these polymorphisms?  There isn’t a lot of concrete information about it, but it seems that you would produce less of the biotinidase enzyme and thus get less biotin from food sources.  Biotin is a water soluble vitamin and not thought to be toxic at higher levels, so trying a biotin supplement may be worthwhile.

Check your genetic data: 

rs13078881 (C is the minor allele, also known as D444H)

  • Polymorphism reduces enzyme activity to just less than half of normal [ref]  If combined with other heterozygous BTD polymorphisms, it can result in partial or profound biotinidase deficiency.

The following SNPs are considered pathogenic for biotinidase deficiency for those who are homozygous for the minor allele.  (This is not a complete list.)

rs28934601 (G is the minor allele)

rs13073139 (A is the minor allele)

rs34885143 (A is the minor allele)

i6008460 (G is the minor allele)

i6008458 (A is the minor allele)

i6008480 (C is the minor allele)

i6008436 (C is the minor allele)


What to do with this information:

If you are heterozygous for one of the BTD polymorphisms and have symptoms of biotin deficiency, biotin supplements are readily available.  It is a water soluble vitamin and not known to be toxic.  Good food sources of biotin include nutritional yeast, which has over 200 mcg per 100g, and chicken liver which has 170 mcg per 130g. [ref]

Comments 2

  • I have this D444H variant on rs13078881, and had my biotinidase levels tested at the recommendation of Dr. Barry Wolf, the man who discovered BTD Deficiency. On my testing lab’s reference scale of 4.8 – 12.0, I was 4.9. This puts me low-normal, but almost twice 30% mean normal (8.4 x .30 = 2.5) which is the partial deficiency level. My levels shouldn’t cause me any problems based on current research, but…

    I developed both neurological and metabolic problems when I reached the age of 50. Metabolically, my significant problem was hypoglycemia. I would readily become hypoglycemic with the slightest bit of fasting or exercise without carb intake. I am overweight by about 20 pounds, and have ample fats stores that should have burned. I also developed fully-body sensory neuropathy that is exacerbated by factors I haven’t yet figured out.

    I started taking Meribin biotin about a year ago after the testing because…well…why not? The effect has been that I have not been hypoglycemic once since then, even when I try to drive myself into with exercise while fasting. Whereas I would routinely see my glucose levels in the 50, I have not seen them below 88 since starting on the biotin. I also immediately started to be able to lose weight again.

    The biotin was not the answer to my neuropathy as I had hoped, but I’m convinced it did resolve my hypoglycemia.

    • Thanks so much for sharing your experience! It is important for people to know that the low end of normal on a lot of tests can still give you problems. I’m glad that you’ve gotten to the root of your problem and that biotin supplements are working for you. Especially for something that is a simple vitamin to try -as you put it.. ‘why not’! I’ve often been frustrated with friends and family who aren’t willing to give something a try.

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