Biotinidase Deficiency and Biotin Holocarboxylase Synthetase Deficiency

Biotin holocarboxylase synthetase and biotinidase deficiencies are biotin-dependent, autosomal recessively inherited disorders. Untreated individuals with both disorders usually develop neurological and cutaneous symptoms during childhood. There is limited information about older children or adults with holocarboxylase synthetase deficiency. Older individuals with biotinidase deficiency may exhibit spastic paresis, scotomata, and progressive optic neuropathy. Both disorders are readily treated with oral biotin supplementation. Asymptomatic individuals with biotinidase deficiency are at risk of developing symptoms at any age. Newborn screening for both disorders has been adopted in many countries. Newborn screening has facilitated identification of presymptomatic individuals, thereby allowing for early treatment and prevention of symptoms.