The function of SDR9C7 (short chain dehydrogenase/reductase family 9C member 7, ENSG00000170426) is as follows. Plays a crucial role in the formation of the epidermal permeability barrier (PubMed:31671075). Catalyzes the NAD+-dependent dehydrogenation of the linoleate 9,10-trans-epoxy-11E-13-alcohol esterified in omega-O-acylceramides (such as in N-[omega-(9R,10R)- epoxy-(13R)-hydroxy-(11E)-octadecenoyloxy]-acylsphing-4E-enine) to the corresponding 13-ketone, the reactive moiety required for binding of epidermal ceramides to proteins (PubMed:31671075). Displays weak conversion of all-trans-retinal to all-trans-retinol in the presence of NADH. Has apparently no steroid dehydrogenase activity (PubMed:19703561). {ECO:0000269|PubMed:19703561, ECO:0000269|PubMed:31671075}.