SLC7A5 and phenylketonuria: In patients with PKU, the mean blood phenylalanine concentration in the first year of life after hospital discharge was nearly identical in both subgroups and reached 0.21 (1SD = 0.15 mmol/l) in carriers of the LAT1 variant (27 cases) and 0.21 (1SD = 0.14) mmol/l in wild-type individuals (27 cases).