FLVCR2 and Fowler syndrome: These homozygous missense mutations S203Y, T430R, and T430M were chosen because the first two former mutations caused lethal Fowler syndrome, whereas the latter mutation caused non-lethal Fowler syndrome.1,2,28,29 We also examined the activity of missense mutations P340L and T430A that were reported in a non-lethal Fowler patient.2 First, we confirmed that these missense mutations did not affect the expression and localization of MFSD7c, except for L483R (Fig. 5a, b).