This study aimed to characterize the developmental and spatial expression patterns of melatonin receptors MTNR1A and MTNR1B in normal human fetal kidneys and in CAKUT phenotypes.<h4>Methods</h4>This study analyzed 40 human fetal kidney specimens, including healthy controls and CAKUT cases (horseshoe kidneys, duplex kidneys, and dysplastic kidneys), obtained from spontaneous abortions and pregnancy terminations. Here, MTNR1A is linked to Horseshoe kidney.