PKDREJ and kidney disorder: More interestingly, the fact that this locus encompasses PKDREJ (Polycystic Kidney Disease and Receptor for Egg Jelly related protein) gene (regional association plot—Supplementary Fig. 3), a homolog of PKD genes associating with kidney disease30, and that X-24513 might be similar in characteristics to C-mannosyltryptophan, reportedly elevated in chronic kidney disease31, highlights the importance of investigating the biological implication of this association in relation to both kidney diseases and ageing.