Night blindness (Biesalski et al., 1999; Seeliger et al., 1999)modest retinal dystrophy (Biesalski et al., 1999; Seeliger et al., 1999)undetectable RBP4 and reduced retinol concentrations in serum (Seeliger et al., 1999). Here, RBP4 is linked to night blindness.