Risk of lung disease in the PI*SS genotype of alpha-1 antitrypsin: an EARCO research project.

BACKGROUND: The PI*S variant is one of the most prevalent mutations within alpha-1 antitrypsin deficiency (AATD). The risk of developing AATD-related lung disease in individuals with the PI*SS genotype is poorly defined despite its substantial prevalence. Our study aimed to characterize this genotype and its risk for lung disease and compare it with the PI*ZZ and PI*SZ genotypes using data from the European Alpha-1 antitrypsin Deficiency Research Collaboration international registry. METHOD: Demographic, clinical, functional, and quality of life (QoL) parameters were assessed to compare the PI*SS characteristics with the PI*SZ and PI*ZZ controls. A propensity score with 1:3 nearest-neighbour matching was performed for the most important confounding variables. RESULTS: The study included 1007 individuals, with PI*SS (n = 56; 5.6%), PI*ZZ (n = 578; 57.4%) and PI*SZ (n = 373; 37.0%). The PI*SS population consisted of 58.9% men, with a mean age of 59.2 years and a mean FEV1(% predicted) of 83.4%. Compared to PI*ZZ individuals they had less frequent lung disease (71.4% vs. 82.2%, p = 0.037), COPD (41.4% vs. 60%, p = 0.002), and emphysema (23.2% vs. 51.9%, p < 0.001) and better preserved lung function, fewer exacerbations, lower level of dyspnoea, and better QoL. In contrast, no significant differences were found in the prevalence of lung diseases between PI*SS and PI*SZ, or lung function parameters, exacerbations, dyspnoea, or QoL. CONCLUSIONS: We found that, as expected, the risk of lung disease associated with the PI*SS genotype is significantly lower compared with PI*ZZ, but does not differ from that observed in PI*SZ individuals, despite having higher serum AAT levels. TRIAL REGISTRATION: www. CLINICALTRIALS: gov (ID: NCT04180319).

The impact of alpha-1 antitrypsin deficiency alleles on lung cancer survival.

Different studies have shown that carrying an alpha-1 antitrypsin (AAT) deficiency allele is an independent risk factor for developing lung cancer (LC). However, to date, little is known regarding whether carrying a deficiency allele may be a prognostic factor in the evolution of LC. A prospective observational study was carried out which consecutively included patients diagnosed with LC in University Hospital "Nuestra Señora de Candelaria" between December 2017 and August 2020. A blood sample was taken from each of the patients in order to determine both AAT serum concentration and genotype. Based on AAT genotype, patients were divided into the deficiency (Pi*≠MM) or non-deficiency (Pi*=MM) group. One hundred and sixty-four patients were included. The average length of follow-up was 13±10 months. Patients were classified as stage I (4.2%), stage II (8.3%), stage III (31.2%) and stage IV (56.3%), according to tumour, node and metastasis (TNM) staging. Twenty-eight patients (17%) were carriers of a deficiency allele (6 Pi*MS, 1 Pi*MZ, 1 Pi*MMheerlen). No significant differences were found with respect to baseline characteristics between Pi*≠MM and Pi*=MM. Patients in the Pi*≠MM group had a higher risk of death in the first 6 months after the LC diagnosis compared to Pi*=MM subjects (HR =2.04; 95% CI: 1.04-4.0; P=0.038). The presence of an AAT deficiency genotype could be a potential prognostic marker in LC. However, larger studies that justify these findings are needed.

Real-time PCR detection of PI*S and PI*Z alleles of SERPINA1 gene using SYBR green.

BACKGROUND: Alpha-1 antitrypsin deficiency is an underdiagnosed genetic condition that predisposes to pulmonary complications and is mainly caused by rs28929474 (PI*Z allele) and rs17580 (PI*S allele) mutations in the SERPINA1 gene. OBJECTIVE: Development of a homogeneous genotyping test for detection of PI*S and PI*Z alleles based on the principles of allele-specific PCR and amplicon melting analysis with a fluorescent dye. METHODS: Sixty individuals, which included all possible genotypes that result from combinations of rs28929474 and rs17580 single nucleotide variants, were assayed with tailed allele-specific primers and SYBR Green dye in a real-time PCR machine. RESULTS: A clear discrimination of mutant and wild-type variants was achieved in the genetic loci that define PI*S and PI*Z alleles. Specific amplicons showed a difference of 2.0 °C in melting temperature for non-S and S variants and of 2.9 °C for non-Z and Z variants. CONCLUSIONS: The developed genotyping method is robust, fast, and easily scalable on a standard real-time PCR platform. While it overcomes the handicaps of non-homogeneous approaches, it greatly reduces genotyping costs compared with other homogeneous approaches.