The association between BMI and/or WC and different measures of kidney health and disease have been reported before in observational (both cross-sectional and longitudinal) studies—increasing obesity correlates with increased incidence of CKD,4–7 end-stage renal disease,8 and a drop in eGFR calculated based on serum levels of creatinine9 or cystatin C.5 The results from our initial observational analysis of >300 000 individuals are fully consistent with these findings. This evidence concerns the gene CST3 and obesity due to melanocortin 4 receptor deficiency.