What is the genetic inheritance pattern of Alpha 1 Antitrypsin Deficiency?

Alpha-1 Antitrypsin Deficiency (AAT deficiency) exhibits an autosomal codominant inheritance pattern. This means that both the normal and abnormal alleles can be expressed simultaneously in an individual who inherits one copy of each variant. Specifically, AAT is produced by the SERPINA1 gene located on chromosome 14. Individuals with two different alleles (for example, the M allele and the Z allele) will have measurable amounts of both normal (M) and abnormal (Z) protein in their serum.

In codominance, neither allele is recessive, so both contribute to the phenotype observed. In the case of AAT deficiency, individuals with two Z alleles are at the greatest risk for developing related health issues, while those with one M allele may have sufficient AAT levels to prevent significant disease.

This genetic mechanism leads to a spectrum of disease severity, depending on the specific alleles inherited and their respective protein production levels. Understanding this inheritance pattern is crucial for genetic counseling and risk assessment in affected families.