Mutations in SLC19A3 (encoding hTHTR2) cause a neurometabolic autosomal recessive disorder known as thiamine metabolism dysfunction syndrome type 2 or biotin-responsive basal ganglia disease (BBGD) or biotin-thiamine responsive basal ganglia disease (BTBGD; OMIM: 607483). This evidence concerns the gene SLC19A3 and biotin-responsive basal ganglia disease.