Clinical Features of the Rare IZ Alpha-1

Title: Clinical Features of the Rare IZ Alpha-1
Author(s): M Herron, D Fraughen, T Carroll, G Kelly, C Gunaratnam, NG McElvaney
Institution: Beaumont Hospital
Poster: Click to view poster
Category: COPD/Asthma
Abstract: The National Targeted Detection Programme for alpha-1 antitrypsin deficiency (AATD) began in Ireland in 2004. Since then, 7,786 cases of AATD have been diagnosed with MZ, SZ and ZZ the most common clinically significant phenotypes. However, serum deficiency and/or clinical suspicion has led to the identification of rarer phenotypes, such as IZ, which are less well understood. The risk of lung and liver disease associated with the IZ phenotype requires clarification.

Since 2004, 24 IZ individuals have been identified. This represents 0.001% of tests performed. The majority were referred for diseases related to alpha-1 antitrypsin deficiency, rather than family screening. The mean alpha-1 antitrypsin level at diagnosis was 0.65 g/L (range 0.49 – 1.06 g/L). Half of those diagnosed were female. The average age at diagnosis was 49 (range 12 - 73). Gender had no influence on the age at diagnosis. Of note, abnormal spirometry was seen in smokers only.

From our data the IZ phenotype appears to represent a moderate risk state akin to MZ and SZ phenotypes where gene-environment interactions are required for lung disease to develop. Therefore, smoking cessation should be a primary focus in IZ smokers.