**Core Concept**
Tuberous sclerosis, also known as tuberous sclerosis complex (TSC), is a rare genetic disorder characterized by the growth of non-cancerous tumors in various parts of the body. It is a multisystem disorder that affects the skin, brain, kidneys, and other organs. The earliest feature of TSC is often a skin manifestation.

**Why the Correct Answer is Right**
The earliest feature of TSC is typically an **adenoma sebaceum**, also known as facial angiofibromas. These are small, reddish-brown skin lesions that appear on the face, particularly around the nose, cheeks, and chin. They are caused by the abnormal growth of fibrous tissue and blood vessels. The presence of adenoma sebaceum is often the first sign of TSC, and it can appear in infancy or early childhood.

**Why Each Wrong Option is Incorrect**
**Option A:** **Shagreen patches** are a type of skin lesion that can occur in TSC, but they are not the earliest feature. They are characterized by thickened, leathery skin patches that appear on the lower back.

**Option B:** **Subependymal giant cell astrocytomas (SEGA)** are a type of brain tumor that can occur in TSC, but they are not the earliest feature. They are typically diagnosed later in childhood or adolescence.

**Option C:** **Renal angiomyolipomas** are a type of kidney tumor that can occur in TSC, but they are not the earliest feature. They are often diagnosed later in childhood or adolescence.

**Clinical Pearl / High-Yield Fact**
The key to diagnosing TSC is to recognize the combination of skin lesions, seizures, and developmental delays. Adenoma sebaceum is often the first sign of TSC, and it can appear in infancy or early childhood.

**Correct Answer: C. Subependymal giant cell astrocytomas (SEGA) are a type of brain tumor that can occur in TSC, but they are not the earliest feature. They are typically diagnosed later in childhood or adolescence.