**Core Concept**
Anencephaly is a congenital anomaly characterized by the absence of a significant portion of the brain and skull, resulting from the failure of the neural tube to close during embryonic development. This condition is often associated with other neural tube defects, such as spina bifida.

**Why the Correct Answer is Right**
Anencephaly is a lethal condition, usually incompatible with life beyond a few days or weeks after birth. This is due to the absence of a significant portion of the brain, including the cerebral cortex, cerebellum, and brainstem, which are essential for regulating vital functions such as breathing, heart rate, and blood pressure. The lack of these structures leads to severe neurological dysfunction and ultimately, death.

**Why Each Wrong Option is Incorrect**
**Option A:** Anencephaly is not typically associated with a normal life expectancy. This statement is incorrect because anencephaly is generally incompatible with long-term survival.

**Option B:** Anencephaly is not a rare condition. This statement is incorrect because anencephaly is a relatively rare congenital anomaly, occurring in approximately 1 in every 5,000 births.

**Option C:** Anencephaly is not typically associated with microcephaly. This statement is incorrect because while anencephaly and microcephaly are both neural tube defects, microcephaly refers specifically to a small head size due to abnormal brain development, whereas anencephaly involves the absence of brain tissue.

**Clinical Pearl / High-Yield Fact**
Anencephaly is often associated with other neural tube defects, such as spina bifida, and may be detected prenatally through ultrasound or maternal serum screening. It is essential to note that anencephaly is usually incompatible with life, and termination of pregnancy may be considered in cases where the fetus is affected.

**Correct Answer: A. Anencephaly is not typically associated with a normal life expectancy.**