title: Quantitative Analytical Method for the Determination of Biotinidase Activity in Dried Blood Spot Samples.
abstract: Biotinidase activity assay is included in most newborn screening protocols, and the positive results are confirmed by quantitative enzyme activity measurements. In our study, we describe a new quantitative analytical method for the determination of biotinidase activity using the blood sample deposited onto filter paper as the assay medium, by predepositing N-biotinyl-p-aminobenzoic acid onto the standard sample collection paper. The analysis of the assay mixture requires a simple extraction step from a dried blood spot followed by the quantification of product by LC-MS. The method provides a simple and reliable enzyme assay method that enables the rapid diagnosis of biotinidase deficiency (BD). Out of the measured 36 samples, 13 were healthy with lower enzyme activities, 16 were patients with partial BD, and 7 were patients with profound BD with residual activity below 10%. Expression of enzyme activity in percentage of mean activity of negative controls allows comparison of the different techniques. The obtained results are in good agreement with activity data determined from both dried blood spots and serum samples, giving an informative diagnostic value.
authors.affiliation: 1st Department of Pediatrics, Semmelweis University , Budapest, 1085 Hungary.
authors.forename: Eszter
authors.initials: E
authors.lastname: Szabó
authors.affiliation: 1st Department of Pediatrics, Semmelweis University , Budapest, 1085 Hungary.
authors.forename: Ildikó
authors.initials: I
authors.lastname: Szatmári
authors.affiliation: 1st Department of Pediatrics, Semmelweis University , Budapest, 1085 Hungary.
authors.forename: László
authors.initials: L
authors.lastname: Szőnyi
authors.affiliation: Faculty of Medicine, Department of Surgery & Cancer, Imperial College , SW7 2AZ London, U.K.
authors.forename: Zoltán
authors.initials: Z
authors.lastname: Takáts
mesh_terms: D000328:Adult; D043523:Biotinidase / Q000097:blood* / Q000378:metabolism; D028921:Biotinidase Deficiency / Q000175:diagnosis; D002851:Chromatography, High Pressure Liquid; D059788:Dried Blood Spot Testing; D004789:Enzyme Activation; D057075:Enzyme Assays; D064368:Healthy Volunteers; D006801:Humans; D007231:Infant, Newborn; D013058:Mass Spectrometry; D015997:Neonatal Screening
chemical_list: D043523:Biotinidase