Cognitive function in early treated biotinidase deficiency: Follow-up of children detected by newborn screening

Abstract

Introduction: Biotinidase deficiency, an inborn error of biotin recycling, is included in many newborn screening programs on the assumption that presymptomatic biotin therapy will prevent all of the complications of the disorder. These complications include cognitive delay. To assess this assumption, we have studied children found to have biotinidase deficiency through newborn screening and treated from early infancy. Methods: Biotinidase screening was performed on a component of the New England Regional Newborn Screening Program. Confirmation of biotinidase deficiency was determined by quantitative serum biotinidase assay. Developmental and cognitive assessment consisted of a battery of age-appropriate tests. Results: The study group consisted of six children with profound biotinidase deficiency (biotinidase activity <10% of normal) and two unaffected sibling controls. Bayley assessment of three affected children revealed developmental scores in the normal to high average range. Cognitive function in the three older children was in the average to superior range. No abnormalities in visual motor integration or in achievement scores were noted. The scores in two children in one family were comparable to those in their two unaffected siblings. Discussion: We found normal developmental or cognitive function in six early treated children with biotinidase deficiency identified by newborn screening. This indicates that early identification and treatment of biotinidase deficiency might preserve full cognitive potential as well as prevent other complications of this disorder.