Test Background Biotinidase deficiency is an autosomal recessive metabolic disorder of biotin recycling. Biotin deficiency leads to multiple carboxylase deficiencies. The estimated incidence of this disorder is 1/60,000 with profound deficiency (activity <10 %) or partial deficiency (10-30 %).
Clinical Indications Symptoms of untreated biotinidase deficiency may appear at any time from 1 week to 10 years of age. The most common early symptoms include seizure activity of various types (myoclonic, grand mal, and focal or infantile spasms) and hypotonia. Other early symptoms include breathing problems (tachypnoea, hyperventilation, stridor and apnoea), skin rashes and alopecia. Later developmental delay, speech problems, ataxia, and vision and hearing problems may occur. Less frequent findings include feeding difficulties, vomiting/diarrhoea, fungal infections, hepatomegaly and splenomegaly.