**Question:** All of the following are true about childhood polycystic kidney disease, except –

A. Polycystic kidney disease (PKD) is a genetic disorder resulting from mutations in the PKD1 or PKD2 genes.
B. PKD is characterized by the formation of numerous fluid-filled cysts in the kidneys, liver, and other organs.
C. PKD is a rare disease affecting only a few individuals in the population.
D. PKD may lead to end-stage renal disease (ESRD) and require renal replacement therapy.

**Correct Answer:** **C. PKD is a rare disease affecting only a few individuals in the population.**

**Core Concept:** Polycystic kidney disease (PKD) is a genetic disorder resulting from mutations in the PKD1 or PKD2 genes. PKD is characterized by the formation of numerous fluid-filled cysts in the kidneys, liver, and other organs. These cysts cause progressive damage to the affected organs, leading to end-stage renal disease (ESRD) and the need for renal replacement therapy.

**Why the Correct Answer is Right:** PKD is a relatively common genetic disorder, affecting approximately 1 in every 1,000 newborns worldwide. Mutation in the PKD1 or PKD2 genes leads to the production of abnormal proteins, which disrupts the normal kidney development and results in the formation of cysts. PKD is a progressive disease, meaning it worsens over time.

**Why Each Wrong Option is Incorrect:**

A. PKD is not solely caused by mutations in PKD1 or PKD2 genes. It can also be caused by mutations in other genes or as a result of chromosomal rearrangements.

B. PKD does not affect only a few individuals in the population. It is a relatively common disorder, affecting approximately 1 in every 1,000 newborns.

D. PKD can lead to ESRD and the need for renal replacement therapy, which is not uncommon in severe cases.

**Clinical Pearl:** PKD is a significant medical issue that should be considered in the differential diagnosis of kidney cysts, particularly in children and young adults. Early diagnosis and monitoring are crucial to manage the disease effectively and prevent complications like hypertension, renal failure, and liver cysts. Timely intervention can improve the quality of life and prognosis of PKD patients.