Multiple carboxylase deficiency is a form of metabolic disorder involving failures of carboxylation

Carboxylation

Carboxylation in chemistry is a chemical reaction in which a carboxylic acid group is introduced in a substrate. The opposite reaction is decarboxylation.-Carboxylation in organic chemistry:In organic chemistry many different protocols exist for carboxylation...

 enzymes.

The deficiency can be in biotinidase

Biotinidase

Biotinidase also known as BTD is an enzyme that in humans is encoded by the BTD gene.- Function :This enzyme allows the body to use and to recycle the B vitamin biotin, sometimes called vitamin H. Biotinidase extracts biotin from food because the body needs biotin in its free, unattached form...

 or holocarboxylase synthetase.

These conditions respond to biotin

Biotin

Biotin, also known as Vitamin H or Coenzyme R, is a water-soluble B-complex vitamin discovered by Bateman in 1916. It is composed of a ureido ring fused with a tetrahydrothiophene ring. A valeric acid substituent is attached to one of the carbon atoms of the tetrahydrothiophene ring...

.

Forms include:

• Holocarboxylase synthetase deficiency
  Holocarboxylase synthetase deficiency
  Holocarboxylase synthetase deficiency is an inherited metabolic disorder in which the body is unable to use the vitamin biotin effectively. This disorder is classified as a multiple carboxylase deficiency, a group of disorders characterized by impaired activity of certain enzymes that depend on...
  
   - neonatal
• Biotinidase deficiency
  Biotinidase deficiency
  Biotinidase deficiency is an autosomal recessive metabolic disorder in which biotin is not released from proteins in the diet during digestion or from normal protein turnover in the cell. This situation results in biotin deficiency....
  
  - late onset

feeding problems,hypotonia,generalised erythematous rash with exfoliation and alopecia,failure to thrive,seizure,coma,developmental delay
tomcat urine,metabolic acidosis,ketosis,hyperammonemia

External links

• http://www.pmh.health.wa.gov.au/services/newborn/health_professionals/disorders/mcd_prof.htm