**Core Concept**
Alpha 1 antitrypsin deficiency is an autosomal codominant genetic disorder caused by mutations in the SERPINA1 gene. This condition leads to the production of abnormal alpha 1 antitrypsin protein, which can accumulate in the liver and cause liver disease or be secreted into the bloodstream, where it can cause lung disease.

**Why the Correct Answer is Right**
The SERPINA1 gene encodes for the alpha 1 antitrypsin protein, which is produced by hepatocytes. Mutations in this gene can lead to the production of abnormal protein that is either retained in the endoplasmic reticulum or secreted into the bloodstream. The most common mutation, ZZ, is a homozygous mutation that leads to the production of an abnormal protein that is primarily retained in the liver, causing liver disease. Other mutations, such as SS, are associated with milder disease and can be secreted into the bloodstream, causing lung disease.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because alpha 1 antitrypsin deficiency is not a sex-linked disorder.
**Option B:** This option is incorrect because the inheritance pattern of alpha 1 antitrypsin deficiency is autosomal codominant, not autosomal dominant.
**Option C:** This option is incorrect because alpha 1 antitrypsin deficiency is caused by mutations in the SERPINA1 gene, not the AAT gene.

**Clinical Pearl / High-Yield Fact**
Alpha 1 antitrypsin deficiency can be diagnosed through genetic testing, which can identify the mutation in the SERPINA1 gene. This is an important consideration in patients with chronic liver disease or emphysema, as early diagnosis and treatment can improve outcomes.

**Correct Answer: D. Autosomal codominant genetic disorder caused by mutations in the SERPINA1 gene.**