Biotinidase deficiency is a genetically conditioned congenital disorder of biotin metabolism. The disease is caused by mutations in the BTD-3p25 gene, located on the short strand of chromosome 3. The BTD gene conditions proper biotinidase synthesis. So far, approximately 150 mutations of this gene have been identified. The incidence proportion is one case per 61 000 births, and the carrier state – one case per 120 births. Biotin (vit. H, B7) is essential in numerous metabolic processes. The initial phase of the disease can be acute, chronic including exacerbations/remissions, progressive, and the symptoms can appear at any age. The diagnosis of patients with late-onset disease is particularly difficult, since the symptoms suggest disorders of different nature, especially neurologic. The diagnosis is based on the analysis of clinical symptoms and laboratory tests, including biotinidase activity. The supplementation of biotin is the treatment of choice. It leads to rapid resolution of symptoms and can protect against permanent consequences of the disease such as optic atrophy, hearing loss or retarded psychomotor development.
Late Onset Subacute Profound Biotinidase Deficiency Caused by a Novel Homozygous Variant c.466-3T>G in the BTD Gene
