**Question:** Berger disease does not involve

A. Cardiac muscle cells
B. Kidney tubules
C. Smooth muscle cells
D. Blood vessels

**Core Concept:**
Berger disease, also known as IgA nephropathy, is a type of glomerulonephritis caused by the deposition of immunoglobulin A (IgA) in the glomerular mesangium. It primarily affects the kidneys and is characterized by inflammation and damage to the kidneys' filtering units, the glomeruli.

**Why the Correct Answer is Right:**
Berger disease primarily affects the glomerular mesangium and renal tubules, leading to renal dysfunction and proteinuria. The correct answer (B) represents kidney tubules, which are not the primary site of involvement in Berger disease. The disease involves glomerular filtration and damage, not kidney tubules.

**Why Each Wrong Option is Incorrect:**
A) Cardiac muscle cells: Berger disease does not affect cardiac muscle cells as it primarily affects the kidneys.
B) Smooth muscle cells: Berger disease does not involve smooth muscle cells as it primarily affects the kidneys and glomeruli.
D) Blood vessels: Although Berger disease can indirectly affect blood vessels due to renal dysfunction, it is not primarily a disease of blood vessels.

**Clinical Pearl:**
Berger disease is an important differential diagnosis to consider in patients presenting with nephrotic syndrome, hypertension, or chronic kidney disease. Understanding the correct site of involvement is crucial for appropriate diagnosis and management of the disease.

**Correct Answer:** B) Kidney tubules