Detection of biocytin in urine of children with congenital biotinidase deficiency.

The possible excretion of biocytin or biotinyl-peptides was investigated in urines of children with congenital biotinidase deficiency. Treatment of urine samples of affected children with normal plasma (as source of biotinidase) liberated additional free biotin (L. plantarum assay), indicating the presence of biotinyl-compounds. Using thin-layer chromatography the occurrence of biocytin was demonstrated in all urine samples of the affected children. In contrast, no biocytin could be detected in urines of healthy subjects.