Screening for biotinidase deficiency in some skin diseases.

Biotinidase deficiency is an inherited, autosomal recessive disorder involving gluconeogenesis, synthesis of fatty acids and catabolism of branched chain amino acids. As the cutaneous manifestations have been described to be a prominent part of the clinical picture, we tested a group of children and adults with various skin lesions. The blood-spot screening test was repeatedly (new disc and new card) positive in some patients suffering from psoriasis and atopic eczema. The quantitative assay does not confirm the decrease of serum biotinidase activity. Some alternative explanations of these results are put forward.