DELAYED-ONSET PROFOUND BIOTINIDASE DEFICIENCY

Children with biotinidase deficiency usually exhibit symptoms at sever al months to years of age. We describe four children who had symptoms later in childhood or during adolescence; they had motor limb weakness , spastic paresis, and eye problems, such as loss of visual acuity and scotomata, rather than the more characteristic symptoms observed in y oung untreated children with the disorder. These older children each h ave different mutations, but they are the same as those of children wh o have exhibited symptoms at an early age. Biotinidase deficiency shou ld be considered in older children who suddenly experience limb weakne ss and/or spastic paresis and eye symptoms.