Chapter 17 - Biotin-responsive Multiple Carboxylase Deficiency

Abstract

This chapter focuses on biochemical role of biotin that is necessary to understand the clinical manifestations of the biotin-responsive diseases. The biotin-responsive multiple carboxylase deficiencies are a group of metabolic disorders whose clinical features include a skin rash and striking neurologic signs. Biotin is widely distributed in most foods, with relatively high concentrations found in liver, egg yolk, cooked grains, cow's milk, and human milk; it is also synthesized by intestinal flora. Biotin-responsive diseases present with one of several clinical patterns, depending upon the specific pathophysiologic mechanisms involved, but the signs usually reflect defective carboxylase activity. Neonatal multiple carboxylase deficiency typically presents in the first several days of life, heralded by vomiting and lethargy. Dietary biotin deficiency most often occurs in patients who have had major segments of their small intestine removed and who are on total parenteral alimentation without supplemental biotin. Dietary biotin deficiency is almost solely restricted to patients with severe gastrointestinal disease on total parenteral nutrition.