Lysinuric protein intolerance [LPI; Online Mendelian Inheritance in Man (OMIM) #222700] is an inborn error of cationic amino acid transport caused by biallelic pathogenic variants in SLC7A7 that results in loss of function of the y+LAT1 transporter (Borsani et al., 1999; Torrents et al., 1999). Here, SLC7A7 is linked to lysinuric protein intolerance.