SLC6A19 encodes the sodium-dependent neutral amino acid transporter B(0)AT1 and mediates the uptake of neutral amino acids across the plasma membrane accompanied by uptake of a sodium ion. The protein is abundantly expressed in the small intestine and kidney (Broer & Gether 2012, Schweikhard & Ziegler 2012). Defects in SLC6A19 can cause Hartnup disorder (HND; MIM:234500), an autosomal recessive abnormality of renal and gastrointestinal neutral amino acid transport characterised by increased urinary and intestinal excretion of neutral amino acids. Symptoms include transient manifestations of rashes, cerebellar ataxia and psychotic behaviour (Broer 2009, Cheon et al. 2010). Some mutations in SLC6A19 are thought to contribute to the phenotypes iminoglycinuria (IG; MIM:242600) and hyperglycinuria (HG; MIM:138500) (Broer et al. 2008).