Molecular characterization of PI * S hangzhou , a SERPINA1 allele from continental China encoding a defective alpha-1-antitrypsin

Genetic Epidemiology of Alpha-1 Antitrypsin Deficiency in Macaronesia

INTRODUCTION

The prevalence of alpha-1 antitrypsin deficiency (AATD) in Macaronesia (i.e., Azores, Madeira, Canary Islands, and Cape Verde archipelagos) is poorly known. Our goal was to update it by selecting the most reliable available articles.

METHOD

Literature search using MEDLINE, Embase (via Ovid), and Google Scholar, until December 2023, for studies on prevalence of AATD in the general population and in screenings, published in peer-reviewed journals.

RESULTS

Three studies carried out in the general population of Madeira, La Palma, and Cape Verde, and three screenings carried out in La Palma (2) and Gran Canaria (1) were selected. The frequencies of PI*S in the general population showed an ascending gradient, from South to North, with values (per thousand) of 35 in Cape Verde, 82 in La Palma, and 180 in Madeira. The PI*Z frequencies showed this same gradient, with values of 2 × 1,000 in Cape Verde, 21 in La Palma, and 25 in Madeira. Screenings detected high percentages of defective alleles, including several rare and null alleles, some unique to these islands.

CONCLUSION

The frequencies of PI*S and PI*Z in Madeira are comparable to the highest in the world. Those of the Canary Islands are similar to those of the peninsular population of Spain, and contrast with the low rates of Cape Verde. Screenings detected high numbers of deficient alleles. These results support the systematic investigation of AATD in clinically suspected patients and in relatives of index cases, to reduce underdiagnosis and apply early preventive and therapeutic measures in those affected.

Sanger and Next-Generation Sequencing of AAT

Sequencing of DNA is normally the final procedure carried out to determine the actual pathogenic variants when the techniques used for genotyping are unable to provide complete identification of both AAT alleles. Gene sequencing of complete SERPINA1 gene by using the Sanger method or next-generation sequencing (NGS) is crucial to enable correct diagnosis in patients with alpha1-antitrypsin deficiency caused by uncommon AAT variants.This protocol explains how to correctly sequence SERPINA1 gene both with Sanger method and NGS.