TBA (22W169)

The prevalence of alpha-1 antitrypsin deficiency detected by targeted liver disease screening in a single centre.

Author(s)

Doherty, S., Herlihy, M., and McKiernan S.

Department(s)/Institutions

Department of Hepatology, St James’s Hospital, Dublin 8.

Introduction

Alpha-1 antitrypsin (AAT) deficiency confers a risk of liver and lung disease. This inherited disease is caused by mutations of the SERPINA1 gene resulting in low levels of the AAT protein. National data reveals that it is the second most common genetic disease in Ireland after cystic fibrosis with carrier rates of 1/25 for Z alleles and 1/10 for S alleles.

Aims/Background

All patients undergoing a targeted liver disease screen in St James’s Hospital are tested for AAT deficiency. Our aim was to ascertain the prevalence of AAT deficiency and phenotypes detected compared to the national figures.

Method

We analysed a cohort of 937 patients who were screened for alpha-1 antitrypsin deficiency as part of a liver disease screen. We collected AAT level, phenotype, risk factors for liver disease, imaging results and FIB-4 scores.

Results

We identified 38 patients with AAT levels of <1 g/L; prevalence of 4.05%. Prevalence of each phenotype: 19 MZ, 7 MS, 7 MM, 4 SZ, 1 SS. Primary liver disease aetiology: NAFLD 7/38, Alcohol 6/38, AAT deficiency 1/38, mixed 24/38.

Conclusions

The most common AAT phenotype detected was MZ(50%). This aligns with national data suggesting that targeted screening, like this, detects a higher rate of Z allele frequency than the general population where the S allele is more common. This supports the hypothesis that Z mutations are of greater significance in the pathogenesis of diseases caused by AAT deficiency. There is scope to increase this database and further analysis may reveal whether certain phenotypes correlate to liver disease severity.