Alpha-1 Antitrypsin Deficiency: The Role of AAT mpx RealFast™ Assay

Alpha-1 Antitrypsin Deficiency (AATD) is a hereditary condition characterized by low serum levels of the protease inhibitor alpha-1-AT (AAT). This deficiency leads to unopposed proteolysis in the lungs, resulting in damage to alveolar tissue and the development of chronic obstructive pulmonary disease (COPD). Individuals carrying specific genetic variants in the SERPINA1 gene are at risk of AATD-related complications, including emphysema and liver disease.

Understanding AATD

AAT is primarily produced in the liver and plays a crucial role in protecting lung tissues from damage caused by proteases like neutrophil elastase. In individuals with AATD, deficient variants of AAT result in reduced serum levels and impaired enzyme function. This deficiency leads to uncontrolled proteolysis in the lungs, contributing to conditions such as emphysema, chronic bronchitis, and persistent airflow obstruction. Additionally, the accumulation of abnormal AAT in the liver can lead to liver disease, including cirrhosis and hepatocellular carcinoma.

The Risk Variants

The most common AATD risk variants are PIS and PIZ, both associated with decreased AAT levels. Individuals with the PIZZ genotype are at the highest risk of developing emphysema and liver disease. PISZ carriers have a lower risk, while individuals with PI*MM, *MS, or *SS genotypes typically have normal or slightly decreased AAT plasma levels.

Diagnostic Significance

Genetic testing for SERPINA1 variants is crucial for diagnosing AATD in individuals presenting with early onset emphysema, bronchiectasis, unexplained liver disease, or necrotizing panniculitis. Detecting PIS and PIZ alleles is essential for identifying AAT-deficient patients accurately.

AAT mpx RealFast™ Assay: Unraveling the Genetics

ViennaLab Diagnostics GmbH offers the AAT RealFast™ Assay, a real-time PCR-based test designed for the simultaneous detection of the PIS and PIZ variants of the SERPINA1 gene. These variants are the most common alleles associated with AAT deficiency. This diagnostic tool helps identify patients with alpha-1 antitrypsin deficiency, distinguishing between various PI genotypes: normal *MM, heterozygous *MS, *MZ, or *SZ, and homozygous *SS or *ZZ.

Principle of the Test

The AAT mpx RealFast™ Assay is based on the fluorogenic 5′ nuclease assay, also known as the TaqMan® assay. Each reaction includes two gene-specific primer pairs amplifying distinct fragments of the SERPINA1 gene and four dual-labeled, allele-specific hydrolysis probes targeting specific sequences in these fragments. During PCR, Taq DNA polymerase’s exonuclease activity cleaves the 5′-fluorescent reporter from the hybridized probe, generating a real-time fluorescent signal proportional to the PCR product.

In normal samples, the wild type probes produce a strong fluorescence signal in one channel (e.g., HEX or Cy5) and little to no signal in the other channel (e.g., FAM or ROX). Conversely, homozygous mutant samples exhibit strong fluorescence in the mutant probe’s channel (e.g., FAM or ROX) and minimal signal in the wild type probe’s channel (e.g., HEX or Cy5). Heterozygous samples display intermediate signals in both channels.

A Comprehensive Solution

The AAT mpx RealFast™ Assay offers a swift and precise method for detecting SERPINA1 variants associated with AATD. By identifying the PIS and PIZ alleles, healthcare professionals can confidently diagnose AAT deficiency, facilitating timely intervention and personalized patient care