Question: What is (are) Kidney Dysplasia ?
Answer: Kidney dysplasia is a condition in which the internal structures of one or both of a fetus kidneys do not develop normally while in the womb. During normal development, two thin tubes of muscle called ureters grow into the kidneys and branch out to form a network of tiny structures called tubules. The tubules collect urine as the fetus grows in the womb. In kidney dysplasia, the tubules fail to branch out completely. Urine that would normally flow through the tubules has nowhere to go. Urine collects inside the affected kidney and forms fluid-filled sacs called cysts. The cysts replace normal kidney tissue and prevent the kidney from functioning. Kidney dysplasia can affect one kidney or both kidneys. Babies with severe kidney dysplasia affecting both kidneys generally do not survive birth. Those who do survive may need the following early in life: - blood-filtering treatments called dialysis - a kidney transplant Children with dysplasia in only one kidney have normal kidney function if the other kidney is unaffected. Those with mild dysplasia of both kidneys may not need dialysis or a kidney transplant for several years. Kidney dysplasia is also called renal dysplasia or multicystic dysplastic kidney.
Source: NIDDK

Question: How many people are affected by Kidney Dysplasia ?
Answer: Kidney dysplasia is a common condition. Scientists estimate that kidney dysplasia affects about one in 4,000 babies.1 This estimate may be low because some people with kidney dysplasia are never diagnosed with the condition. About half of the babies diagnosed with this condition have other urinary tract defects.2
Source: NIDDK