Which of the following statements is wrong regarding adult polycystic kidney disease?
**Core Concept**
Adult polycystic kidney disease (APKD) is a genetic disorder characterized by the growth of numerous cysts in the kidneys, leading to renal impairment and eventually end-stage renal disease. The disease is caused by mutations in the PKD1 or PKD2 genes, which encode for polycystin-1 and polycystin-2 proteins, respectively.
**Why the Correct Answer is Right**
The correct answer is related to the pathophysiology of APKD. The disease is characterized by the abnormal proliferation and differentiation of renal epithelial cells, leading to the formation of cysts. The cysts are initially lined by a single layer of cuboidal epithelium, but as they grow, they become lined by a stratified epithelium, which is thought to be responsible for the production of excess fluid and electrolytes.
**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect because APKD is indeed a genetic disorder, and the PKD1 and PKD2 genes are responsible for encoding the polycystin-1 and polycystin-2 proteins, respectively. Mutations in these genes lead to the development of APKD.
**Option B:** Incorrect because cysts in APKD do indeed grow over time, leading to an increase in kidney size and a decrease in kidney function.
**Option C:** Incorrect because the exact mechanism of cyst formation in APKD is not fully understood, but it is thought to involve the abnormal proliferation and differentiation of renal epithelial cells.
**Clinical Pearl / High-Yield Fact**
The earliest clinical manifestation of APKD is often hypertension, which can occur in the absence of detectable renal impairment. This is due to the abnormal production of renin and other vasoactive substances by the cystic kidneys.
**Correct Answer:** None given.