Pregnancy, however, alters biotin catabolism and despite a regular biotin intake, half of the pregnant women in the U.S. are marginally biotin deficient. See also
Biotinidase deficiency
Holocarboxylase synthetase deficiency
Multiple carboxylase deficiency

References
Possible references
Adhisivam B, Mahto D, Mahadevan S (March 2007). "Biotin responsive limb weakness". Indian Pediatr. 44 (3): 228–30. PMID 17413203. Baykal T, Gokcay G, Gokdemir Y, Demir F, Seckin Y, Demirkol M, Jensen K, Wolf B (2005). "Asymptomatic adults and older siblings with biotinidase deficiency ascertained by family studies of index cases". J. Inherit. Metab. Dis. 28 (6): 903–12. doi:10.1007/s10545-005-0161-3. PMID 16435182. S2CID 22277450. Boas MA (1927). "The Effect of Desiccation upon the Nutritive Properties of Egg-white". Biochem. J. 21 (3): 712–724.1. doi:10.1042/bj0210712. PMC 1251968. PMID 16743887. Dobrowolski SF, Angeletti J, Banas RA, Naylor EW (February 2003). "Real time PCR assays to detect common mutations in the biotinidase gene and application of mutational analysis to newborn screening for biotinidase deficiency". Mol. Genet. Metab. 78 (2): 100–7. doi:10.1016/S1096-7192(02)00231-7. PMID 12618081. Forbes GM, Forbes A (1997). "Micronutrient status in patients receiving home parenteral nutrition". Nutrition. 13 (11–12): 941–4. doi:10.1016/S0899-9007(97)00334-1. PMID 9433708. Genc GA, Sivri-Kalkanoğlu HS, Dursun A, Aydin HI, Tokatli A, Sennaroglu L, Belgin E, Wolf B, Coşkun T (February 2007). "Audiologic findings in children with biotinidase deficiency in Turkey". Int. J. Pediatr. Otorhinolaryngol. 71 (2): 333–9. doi:10.1016/j.ijporl.2006.11.001. PMID 17161472. González EC, Marrero N, Frómeta A, Herrera D, Castells E, Pérez PL (July 2006). "Qualitative colorimetric ultramicroassay for the detection of biotinidase deficiency in newborns". Clin. Chim. Acta. 369 (1): 35–9. doi:10.1016/j.cca.2006.01.009. PMID 16480705.
DNA mutational analysis revealed that the child was homozygous for a novel E64K mutation and that his mother and father were heterozygous for the novel E64K mutation. Potential causes
Smoking: Recent studies suggest that smoking can lead to marginal biotin deficiency because it speeds up biotin catabolism (especially in women). Excessive alcohol consumption
Excessive consumption of antidiuretics or inadequate levels of antidiuretic hormone
Intestinal malabsorption caused by short bowel syndrome

Biochemistry
Biotin is a coenzyme for five carboxylases in the human body (propionyl-CoA carboxylase, methylcrotonyl-CoA carboxylase, pyruvate carboxylase, and 2 forms of acetyl-CoA carboxylase.) Therefore, biotin is essential for amino acid catabolism, gluconeogenesis, and fatty acid metabolism. Biotin is also necessary for gene stability because it is covalently attached to histones. Biotinylated histones play a role in repression of transposable elements and some genes. Normally, the amount of biotin in the body is regulated by dietary intake, biotin transporters (monocarboxylate transporter 1 and sodium-dependent multivitamin transporter), peptidyl hydrolase biotinidase (BTD), and the protein ligase holocarboxylase synthetase. When any of these regulatory factors are inhibited, biotin deficiency could occur. Diagnosis
The most reliable and commonly used methods for determining biotin status in the body are:

excretion of 3-hydroxyisovaleric acid and biotin in urine
activity of propionyl-CoA carboxylase in lymphocytes

Treatment
In the United States, biotin supplements are readily available without a prescription in amounts ranging from 300 to 10,000 micrograms (30 micrograms is identified as Adequate Intake). Epidemiology
Since biotin is present in many foods at low concentrations, deficiency is rare except in locations where malnourishment is very common.