Almost all food contain significant quantities of biotin, but it is most found in plants, liver, egg yolk, soybean products, and yeast.
Daily biotin requirement is low (150-300 ug/d).
Intestinal flora synthesizes significant quantities of biotin.
Biotin is recycled in the body and eventually lost in urine and feces.
Is caused by two inherited defects in metabolism:
Vitamin B7 deficiency
DDx involves genetic disorders with impaired carboxylation.
Vitamin B9 deficiency
Biotinidase Deficiency 
Vitamin B12 deficiency
Holocarboxylase Synthetase Deficiency 
Vitamin A deficiency
Carnitine Deficiency