**Core Concept**
Alpha 1 antitrypsin deficiency is a genetic disorder characterized by the deficiency of the enzyme alpha 1 antitrypsin, which protects the lungs from the enzyme neutrophil elastase. This deficiency can lead to the destruction of lung tissue and is often associated with chronic obstructive pulmonary disease (COPD).

**Why the Correct Answer is Right**
The correct answer is related to the genetic origin of alpha 1 antitrypsin deficiency. Alpha 1 antitrypsin is encoded by the SERPINA1 gene, which is located on chromosome 14. Mutations in this gene can lead to the production of abnormal alpha 1 antitrypsin protein, which can accumulate in the liver and cause liver damage. The most common mutation associated with alpha 1 antitrypsin deficiency is the ZZ mutation, which results in a premature stop codon and a non-functional protein.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is not correct because alpha 1 antitrypsin deficiency is not primarily associated with a deficiency of the enzyme alpha 1 antitrypsin itself, but rather with a genetic mutation that leads to the production of abnormal protein.

**Option B:** This option is not correct because alpha 1 antitrypsin deficiency is not primarily associated with a deficiency of the enzyme neutrophil elastase, but rather with the inability of alpha 1 antitrypsin to protect the lungs from neutrophil elastase.

**Option C:** This option is not correct because while alpha 1 antitrypsin deficiency can be associated with liver disease, it is not the only association and is not the primary reason for the deficiency.

**Clinical Pearl / High-Yield Fact**
Alpha 1 antitrypsin deficiency is often inherited in an autosomal codominant pattern, meaning that individuals with two copies of the mutated gene (homozygous) are more severely affected than those with one copy (heterozygous).

**Correct Answer: A. PiZZ genotype**