The essential role of VLC-SFA for skin function and survival is unequivocally demonstrated in homozygous STGD3 knockin mice and homozygous global Elovl4 knockout mice that die at birth (23, 31, 32, 33) and in humans with homozygous ELOVL4 mutations who die within the first decade of life from a number of neurological and skin disorders (40, 41). This evidence concerns the gene ELOVL4 and skin disorder.