Also known as vitamin B7, coenzyme R, W Factor, and vitamin H

Holocarboxylase Synthetase (HCS) Deficiency

HCS deficiency is a genetic disorder that manifests early in Japanese infants.

A type of multiple carboxylase deficiency, HCS deficiency is a recessive genetic disorder that typically appears up until 10 years of age. The most common symptom at onset is respiratory problems, although diabetic ketoacidosis was reported as an initial finding in one patient. Age of onset seems to be partially dependent upon ethnicity, with non-Japanese patients first presenting symptoms later in age than Japanese infants.55

Defects in the holocarboxylase synthetase enzyme block biotin from binding to carboxylase enzymes. HCS deficiency may also impact DNA functions, since holocarboxylase synthetase mediates the biotinylation of histones (DNA-binding proteins). In turn this reduces the biotin-dependent carboxylase enzyme metabolic activities, and without treatment can lead to permanent neurological damage, coma, and even death.7, 56

Even though there are normal levels of biotin in the blood, patients with this condition require high doses of biotin to compensate for this lack of enzyme.56

Breakdown of fat instead of glucose as an energy source due to lack of insulin.55
Attachment of a biotin molecule.9
Disclaimer: This website is not intended to replace professional consultation, diagnosis, or treatment by a licensed physician. If you require any medical related advice, contact your physician promptly. Information presented on this website is exclusively of a general reference nature. Do not disregard medical advice or delay treatment as a result of accessing information at this site. Just Answer is an external service not affiliated with