Obstacles to Early Diagnosis and Treatment of Alpha-1 Antitrypsin Deficiency: Current Perspectives

Characteristics associated with SF-36 in alpha-1 antitrypsin deficiency-associated COPD: a cross-sectional analysis

BACKGROUND

Generic measures of health-related quality of life (HRQoL), such as the 36-Item Short Form Survey (SF-36), are widely used in assessing chronic conditions. These tools have an advantage over disease-specific instruments, as they allow comparisons across different health conditions and with the general population. In alpha-1 antitrypsin deficiency (AATD)-associated chronic obstructive pulmonary disease (COPD), HRQoL research remains scarce. This cross-sectional study evaluates the factors associated with HRQoL in a cohort of patients with AATD-associated COPD.

METHODS

Our study included participants of AlphaNet (2008-2019), a health management organization for people with AATD in the US who are prescribed augmentation therapy. Norm-based SF-36 scores for the mental and physical component summary scores (MCS and PCS, mean of 50 ± 10 in the general US population) and 8 individual scales were evaluated. Individuals with lung disease and data available on ≥1 measurement on any SF-36 scale and clinically relevant characteristics such as modified Medical Research Council (mMRC) scale, exacerbation frequency, productive cough, and use of oxygen were included in these analyses. Generalized linear regression models were fit to examine the association of baseline characteristics with MCS and PCS scores. Age, sex, regular use of oxygen, exacerbation frequency, mMRC, and productive cough were included in these models.

RESULTS

Participants (n=4398, mean age 57.6 [SD=10.6] years, 45.4% female) had a mean MCS score of 51.2 ± 10.8 and PCS of 36.3 ± 9.8. The average mMRC score was 2.4 ± 1.3, and 56.4% had 2 or more exacerbations per year. Overall, the physical component of SF-36 was more severely impacted compared to the mental component. In multivariable regression analyses, PCS scores were significantly associated with exacerbation frequency, mMRC, regular use of oxygen, and productive cough; MCS was associated with age, sex, exacerbation frequency, mMRC, and productive cough.

CONCLUSIONS

These findings demonstrate that patient-perceived physical health is significantly impaired in this cohort of people with AATD-associated COPD compared to mental health. Longitudinal studies are needed to evaluate the change in physical and mental health status over time in this population.

Improving Detection of Alpha-1 Antitrypsin Deficiency: Role of the Allergist

Alpha-1 antitrypsin deficiency (AATD) is a genetic disorder that manifests as lung and/or liver disease. Because symptoms of AATD overlap with those of common pulmonary and hepatic conditions, AATD is often misdiagnosed, which has resulted in substantial underdiagnosis of AATD worldwide. Although screening patients for AATD is recommended, the lack of procedures to facilitate testing remains a barrier to accurate diagnosis of AATD. Delays in AATD diagnosis can worsen outcomes for patients by postponing appropriate disease-modifying treatments. Patients with AATD-related lung disease experience symptoms similar to other obstructive lung disorders and are often misdiagnosed for years. In addition to existing screening guidelines, we recommend that screening for AATD become a standard part of allergists' workups of patients with asthma and fixed obstructive disease, chronic obstructive pulmonary disease, bronchiectasis without known origin, and patients under consideration for treatment with biologics. This Rostrum article reviews screening and diagnostic tests available in the United States and emphasizes evidence-based strategies to increase testing frequency and improve AATD detection rates. We underscore the pivotal role of allergists in managing care for patients with AATD. Finally, we urge health care providers to be aware of potentially poor clinical outcomes among patients with AATD during the coronavirus disease 2019 pandemic.

Estimating the Prevalence of AATD Patients in the UK to Identify Underdiagnosis and Determine the Eligibility for Potential Augmentation Therapy

Purpose

Alpha 1 antitrypsin deficiency (AATD) is a genetic risk factor for chronic obstructive pulmonary disease (COPD). Whilst testing for the condition is relatively simple, there is a disconnect in published literature between genetic epidemiology and numbers of patients known to specialists. This makes planning services for patients difficult. We aimed to estimate the number of patients likely to have lung disease eligible for specific AATD therapy within the UK.

Patients and Methods

The THIN database was used to determine the prevalence of AATD and symptomatic COPD. This, and published rates of AATD were used to extrapolate THIN data to the population size of the UK to give an indicative population size for symptomatic AATD patients who have lung disease. The Birmingham AATD registry was used to describe age at diagnosis, rate of lung disease and symptomatic lung disease for patients with PiZZ (or equivalent) AATD, together with the time from symptom onset to diagnosis, in order to aid interpretation of the THIN data and improve modeling.

Results

THIN data showed COPD prevalence of 3%, and AATD prevalence of 0.005-0.2%, depending on how stringently AATD diagnostic codes were applied. The majority of Birmingham AATD patients were diagnosed between the ages 46-55, whilst patients recorded in THIN tended to be older. The rate of COPD was similar in the THIN and Birmingham patients diagnosed with AATD. Modelling to the size of the UK demonstrated a likely symptomatic AATD population of between 3016 and 9866 people.

Conclusion

AATD is likely to be under-diagnosed in the UK. Based on projected patient numbers an expansion to specialist services is desirable, in particular if specific therapy for AATD such as augmentation were to be introduced to the healthcare system.

Gene therapy for alpha-1 antitrypsin deficiency: an update

INTRODUCTION

Altering the human genetic code has been explored since the early 1990s as a definitive answer for the treatment of monogenic and acquired diseases which do not respond to conventional therapies. In Alpha-1 antitrypsin deficiency (AATD) the proper synthesis and secretion of alpha-1 antitrypsin (AAT) protein is impaired, leading to its toxic hepatic accumulation along with its pulmonary insufficiency, which is associated with parenchymal proteolytic destruction. Because AATD is caused by mutations in a single gene whose correction alone would normalize the mutant phenotype, it has become a popular target for both augmentation gene therapy and gene editing. Although gene therapy products are already a reality for the treatment of some pathologies, such as inherited retinal dystrophy and spinal muscular atrophy, AATD-related pulmonary and, especially, liver diseases still lack effective therapeutic options.

AREAS COVERED

Here, we review the course, challenges, and achievements of AATD gene therapy as well as update on new strategies being developed.

EXPERT OPINION

Reaching safe and clinically effective expression of the AAT is currently the greatest challenge for AATD gene therapy. The improvement and emergence of technologies that use gene introduction, silencing and correction hold promise for the treatment of AATD.

The impact of diagnostic delay on survival in alpha-1-antitrypsin deficiency: results from the Austrian Alpha-1 Lung Registry

BACKGROUND

Alpha-1-antitrypsin (AAT) deficiency (AATD) is a genetic disorder that can manifest as lung disease. A delay between onset of symptoms and diagnosis of AATD is common and associated with worse clinical status and more advanced disease stage but the influence on survival is unclear.

OBJECTIVE

We aimed to investigate the impact of diagnostic delay on overall survival (OS) and transplant-free survival (TS) in AATD patients.

METHODS

We analysed 268 AATD patients from the prospective multi-centre Austrian Alpha-1 Lung (AAL) Registry, employing descriptive statistics, Chi-square-test as well as univariable (Kaplan-Meier plots, log-rank test) and multivariable survival analysis (Cox regression).

RESULTS

The predominant phenotype was Pi*ZZ (82.1%). At diagnosis, 90.2% had an AAT level below 0.6 g/L. At inclusion, 28.2% had never smoked, 68.0% had quit smoking and 3.8% continued to smoke. Lung disease was diagnosed in 98.5%, thereof most patients were diagnosed with emphysema (63.8%) and/or chronic obstructive pulmonary disease (44.0%). Median diagnostic delay was 5.3 years (inter-quartile range [IQR] 2.2-11.5 years). In multivariable analysis (n = 229), a longer diagnostic delay was significantly associated with worse OS (hazard ratio [HR] 1.61; 95% CI 1.09-2.38; p = 0.016) and TS (HR 1.43; 95% CI 1.08-1.89; p = 0.011), independent from age, smoking status, body mass index (BMI), forced expiratory volume in one second (FEV₁) and long-term oxygen treatment. Furthermore, BMI, age and active smoking were significantly associated with worse OS as well as BMI, active smoking and FEV₁ were with worse TS.

CONCLUSIONS

A delayed diagnosis was associated with significantly worse OS and TS. Screening should be improved and efforts to ensure early AATD diagnosis should be intensified.

Structural characterization and conformational dynamics of alpha-1 antitrypsin pathogenic variants causing alpha-1-antitrypsin deficiency

Background: Alpha-1 antitrypsin deficiency (A1ATD) is a progressive lung disease caused by inherited pathogenic variants in the SERPINA1 gene. However, their actual role in maintenance of structural and functional characteristics of the corresponding α-1 anti-trypsin (A1AT) protein is not well characterized. Methods: The A1ATD causative SERPINA1 missense variants were initially collected from variant databases, and they were filtered based on their pathogenicity potential. Then, the tertiary protein models were constructed and the impact of individual variants on secondary structure, stability, protein-protein interactions, and molecular dynamic (MD) features of the A1AT protein was studied using diverse computational methods. Results: We identified that A1ATD linked SERPINA1 missense variants like F76S, S77F, L278P, E288V, G216C, and H358R are highly deleterious as per the consensual prediction scores of SIFT, PolyPhen, FATHMM, M-CAP and REVEL computational methods. All these variants were predicted to alter free energy dynamics and destabilize the A1AT protein. These variants were seen to cause minor structural drifts at residue level (RMSD = <2Å) of the protein. Interestingly, S77F and L278P variants subtly alter the size of secondary structural elements like beta pleated sheets and loops. The residue level fluctuations at 100 ns simulation confirm the highly damaging structural consequences of all the six missense variants on the conformation dynamics of the A1AT protein. Moreover, these variants were also predicted to cause functional deformities by negatively impacting the binding energy of A1AT protein with NE ligand molecule. Conclusion: This study adds a new computational biology dimension to interpret the genotype-protein phenotype relationship between SERPINA1 pathogenic variants with its structural plasticity and functional behavior with NE ligand molecule contributing to the Alpha-1-antitrypsin deficiency. Our results support that A1ATD complications correlates with the conformational flexibility and its propensity of A1AT protein polymerization when misfolded.

Disease burden associated with alpha-1 antitrypsin deficiency: systematic and structured literature reviews

Alpha-1 antitrypsin deficiency (AATD) is a rare genetic disorder characterised by reduced levels of circulating alpha-1 antitrypsin and an increased risk of lung and liver disease. Recent reviews of AATD have focused on diagnosis, epidemiology and clinical management; comprehensive reviews examining disease burden are lacking. Therefore, we conducted literature reviews to investigate the AATD disease burden for patients, caregivers and healthcare systems. Embase, PubMed and Cochrane libraries were searched for AATD publications from database inception to June 2021, in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Most published AATD studies were small and short in duration, with variations in populations, designs, measures and outcomes, complicating cross-study comparisons. AATD was associated with significant pulmonary and hepatic morbidity. COPD, emphysema and bronchiectasis were common lung morbidities, where smoking was a key risk factor. Fibrosis and steatosis were the most common liver complications reported in patients with a PiZ allele. Health status analyses suggested a poorer quality of life for AATD patients diagnosed with COPD versus those with non-AATD-associated COPD. The burden for caregivers included loss of personal time due to caring responsibilities, stress and anxiety. AATD was also associated with high direct medical costs and healthcare resource utilisation.

Assessment of Patient Perspectives and Barriers to Self-Infusion of Augmentation Therapy for Alpha-1 Antitrypsin Deficiency During the COVID-19 Pandemic

Introduction

Alpha-1 antitrypsin (AAT) deficiency is an autosomal co-dominant genetic condition that predisposes individuals to pulmonary and hepatic disease, and in severe cases is treated with augmentation by intravenous infusion. Our aim was to assess patient reluctance to transition to self-administered augmentation of alpha-1-antitrypsin, during the pandemic of SARS-CoV-2.

Methods

A phone questionnaire was administered to 22 patients with severe alpha-1-antitrypsin deficiency who were currently receiving AAT augmentation therapy. Inclusion criteria included patients \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\ge$$\end{document}≥ 18 years old, diagnosed with AATD, and receiving intravenous AAT protein augmentation therapy. Information was gathered regarding demographics, perspectives on transitioning to self-administered treatment, and anxiety and depression prevalence. Results were collected anonymously using REDCap. Joint and marginal statistical analysis was done to quantify links between participants’ willingness to transition to self-infusion and correlations with sex, age, years of therapy, anxiety, and depression.

Results

Of 22 patients, 14 were male and eight were female. Ages ranged from 36 to 79 years, with an average of 62.5. Genotypes were ZZ (14), MZ (3), and SZ (2) among others. Average length of intravenous augmentation was 9.5 years. The majority, 16 participants, were aware self-infusion was an option. Eight participants were willing to consider transitioning to self-infusion if trained and educated. Eight patients reported that fear of COVID-19 transmission influenced their decision-making. Above-normal anxiety, and depression scores, were found in four, and six patients, respectively. Neither sex, age, years of treatment, anxiety, or depression were found to be associated with willingness to consider self-infusion therapy.

Conclusions

Although there are many reasons AATD patients may benefit from AAT self-infusion, including decreased exposure to SARS-CoV-2, the majority preferred home nurse-infused therapy.

Supplementary Information

The online version contains supplementary material available at 10.1007/s41030-022-00182-z.

Current views in chronic obstructive pulmonary disease pathogenesis and management

Chronic obstructive pulmonary disease (COPD) is a progressive lung dysfunction caused mainly by inhaling toxic particles and cigarette smoking (CS). The continuous exposure to ruinous molecules can lead to abnormal inflammatory responses, permanent damages to the respiratory system, and irreversible pathological changes. Other factors, such as genetics and aging, influence the development of COPD. In the last decade, accumulating evidence suggested that mitochondrial alteration, including mitochondrial DNA damage, increased mitochondrial reactive oxygen species (ROS), abnormal autophagy, and apoptosis, have been implicated in the pathogenesis of COPD. The alteration can also extend to epigenetics, namely DNA methylation, histone modification, and non-coding RNA. This review will discuss the recent progressions in COPD pathology, pathophysiology, and molecular pathways. More focus will be shed on mitochondrial and epigenetic variations related to COPD development and the role of nanomedicine as a potential tool for the prevention and treatment of this disease.