Renal agenesis is a medical condition where one or both kidneys fail to develop during fetal growth. This can occur as a result of genetic factors or environmental influences. The most common form is unilateral renal agenesis, where only one kidney is absent, while bilateral renal agenesis involves the absence of both kidneys, which is often fatal shortly after birth. Individuals with unilateral renal agenesis can lead normal lives with the remaining kidney, which typically compensates for the loss. However, those with bilateral renal agenesis require immediate medical intervention, often including dialysis or kidney transplantation, to survive.