KDSR (3-ketodihydrosphingosine reductase) enzyme associated with the cytosolic face of the endoplasmic reticulum membrane catalyzes the reduction of 3-ketosphingoid by NADPH to form sphingoid (Kihara and Igarashi 2004). Defects in KDSR or missing activity causes Erythrokeratodermia (EKVP4, MIM:617526), associated with sphingolipid dysregulation (Boyden et al., 2017). While there is no data on substrates other than 3-ketosphinganine, it is probable that KDSR has activity toward 3-ketosphingoids with other chain lengths than C16.