American Thoracic Society; European Respiratory Society. American Thoracic Society/European Respiratory Society statement: standards for the diagnosis and management of individuals with alpha-1 antitrypsin deficiency. Am J Respir Crit Care Med. 2003;168:818-900. [PMID: 14522813 DOI: 10.1164/rccm.168.7.818]

Alpha-1 Antitrypsin Screening in a Selected Cohort of Patients Affected by Chronic Pulmonary Diseases in Naples, Italy

INTRODUCTION

Alpha-1 antitrypsin deficiency (AATD) is a genetic condition associated with several respiratory diseases in patients with severe protein deficiency. AATD is often late diagnosed or underdiagnosed. Diagnosis frequently occurs in patients with chronic obstructive pulmonary disease and emphysema characterized by frequent exacerbations and over ten years' duration. The purpose of this study was to evaluate the incidence of alpha-1 antitrypsin deficiency in patients with the chronic pulmonary disease after a thorough screening in the city of Naples in southern Italy.

MATERIALS AND METHODS

Two hundred patients suffering from respiratory pathology (chronic obstructive pulmonary disease (COPD), emphysema, asthma, or bronchiectasis) were examined and evaluated in our outpatients' clinic and tested for serum levels of AAT. Patients who had a respiratory disease suspected of AATD and/or serum AAT < 120 mg/dL underwent genetic testing. Genetic screening was performed on samples from 141 patients.

RESULTS

A total of 36 patients had an intermediate deficiency of AAT levels. Among them, 8 were PI*MZ, 6 were PI*MS and 22 had rare pathological mutations. Five patients had a severe AATD, all were composite heterozygous with S or Z allele, while the other allele had a rare pathological mutation.

CONCLUSIONS

The incidence of genetic defects as AATD in the population of patients affected by chronic respiratory disorders is always a matter of discussion because of the frequent interaction between genes and environmental causes. In our series, numerous rare variants and compound heterozygosity have been described. No homozygous patients have been described. The present is one of few studies available on the incidence of rare variants in the geographic area of the city of Naples. So, our results could be considered interesting not only to know the incidence of AATD and its related rare mutations but also to support early diagnosis and treatments for patients with chronic pulmonary disease and frequent exacerbation and to fight the association with environmental causes of pulmonary damages as smoking.

Liver transplantation for rare liver diseases and rare indications for liver transplant

Liver transplantation (LT) is currently considered the gold standard treatment for end-stage liver failure. Compared to the first decades of its use, LT is associated with lower comorbidity and mortality, with a 5-year survival over 70%. Worldwide, liver cirrhosis and hepatocellular carcinoma represent the major indications to LT. However, almost 1% of LT is performed for rare diseases or rare indications, which include non-hepatocellular malignancy, vascular disorders, metabolic and congenital liver disorders. These diseases can lead to hepatocellular necrosis, biliary tree abnormality and/or hepatomegaly. Most of these diseases are not associated with liver failure but in highly selected patients, LT represent an effective therapy improving the overall survival and quality of life. Rare indications for LT often overlap with rare diseases. However, rare LT indications for non-rare diseases are rising in the last decades, especially for benign primary liver tumor, colon rectal liver metastasis, neuroendocrine liver metastasis, and cholangiocarcinoma (CCA). Non-rare diseases with rare indication for LT and rare adult disease with an indication for LT are categorized and discussed in detail, focusing on some disorders for which the literature provides a more definitive evidence base. Early referral to a transplant center is encouraged to provide an effective therapeutic option in these non-standard indications for LT.

Alpha-1 antitrypsin (AAT) augmentation therapy in individuals with the PI*MZ genotype: a pro/con debate on a working hypothesis

Alpha-1 antitrypsin deficiency (AATD) is a significantly under-diagnosed genetic condition caused by reduced levels and/or functionality of alpha-1 antitrypsin (AAT), predisposing individuals to lung, liver or other systemic diseases. The management of individuals with the PI*MZ genotype, characterized by mild or moderate AAT deficiency, is less clear than of those with the most common severe deficiency genotype (PI*ZZ). Recent genetic data suggest that the PI*MZ genotype may be significantly more prevalent than currently thought. The only specific treatment for lung disease associated with severe AATD is the intravenous infusion of AAT augmentation therapy, which has been shown to slow disease progression in PI*ZZ individuals. There is no specific evidence for the clinical benefit of AAT therapy in PI*MZ individuals, and the risk of emphysema development in this group remains controversial. As such, current guidelines do not support the use of AAT augmentation in PI*MZ individuals. Here, we discuss the limited data on the PI*MZ genotype and offer pro and con perspectives on pursuing an AAT-specific therapeutic strategy in PI*MZ individuals with lung disease. Ultimately, further research to demonstrate the safety, risk/benefit balance and efficacy of AAT therapy in PI*MZ individuals is needed.

Known Mutations at the Cause of Alpha-1 Antitrypsin Deficiency an Updated Overview of SERPINA1 Variation Spectrum

Alpha-1-Antitrypsin deficiency (AATD), caused by SERPINA1 mutations, is one of the most prevalent Mendelian disorders among individuals of European descend. However, this condition, which is characterized by reduced serum levels of alpha-1-antitrypsin (AAT) and associated with increased risks of pulmonary emphysema and liver disease in both children and adults, remains frequently underdiagnosed. AATD clinical manifestations are often correlated with two pathogenic variants, the Z allele (p.Glu342Lys) and the S allele (p.Glu264Val), which can be combined in severe ZZ or moderate SZ risk genotypes. Yet, screenings of AATD cases and large sequencing efforts carried out in both control and disease populations are disclosing outstanding numbers of rare SERPINA1 variants (>500), including many pathogenic and other likely deleterious mutations. Generally speaking, pathogenic variants can be subdivided into either loss- or gain-of-function according to their pathophysiological effects. In AATD, the loss-of-function is correlated with an uncontrolled activity of elastase by its natural inhibitor, the AAT. This phenomenon can result from the absence of circulating AAT (null alleles), poor AAT secretion from hepatocytes (deficiency alleles) or even from a modified inhibitory activity (dysfunctional alleles). On the other hand, the gain-of-function is connected with the formation of AAT polymers and their switching on of cellular stress and inflammatory responses (deficiency alleles). Less frequently, the gain-of-function is related to a modified protease affinity (dysfunctional alleles). Here, we revisit SERPINA1 mutation spectrum, its origins and population history with a greater emphasis on variants fitting the aforementioned processes of AATD pathogenesis. Those were selected based on their clinical significance and wider geographic distribution. Moreover, we also provide some directions for future studies of AATD clinically heterogeneity and comprehensive diagnosis.

Liquid Chromatography-Tandem Mass Spectrometry-Based α1-Antitrypsin (AAT) Testing

OBJECTIVES

Failure to produce sufficient quantities of functional α1-antitrypsin (AAT) can result in AAT deficiency (AATD) and significant comorbidities. Laboratory testing plays a vital role in AATD, with diagnosis requiring documentation of both a low AAT level and a mutated allele. This retrospective evaluation examines the efficacy of a liquid chromatography-tandem mass spectrometry (LC-MS/MS) (proteotyping)-based algorithm for AATD detection.

METHODS

A 16-month retrospective data analysis was performed on two cohorts: 5,474 samples tested with the proteotype-based algorithm and 16,147 samples directly tested by isoelectric focusing (IEF) phenotyping.

RESULTS

LC-MS/MS reduced the rate of IEF testing by 97%. The 3% of cases reflexed to IEF resulted in 12 (0.2%) additional phenotype findings. Retrospectively applying the proteotype-based algorithm to the IEF cohort demonstrated a 99.9% sensitivity for the detection of deficiency-associated phenotypes. Most deficiency phenotypes missed by the proteotyping algorithm would come from heterozygous patients with an F, I, or P paired to an S or Z. In all of these cases, patient AAT levels were greater than 70 mg/dL, above the threshold for AAT augmentation therapy.

CONCLUSIONS

The proteotype algorithm is a sensitive and cost-effective approach for the diagnosis of clinical AAT deficiency.

Comparison of different algorithms in laboratory diagnosis of alpha1-antitrypsin deficiency

OBJECTIVES

Alpha1-antitrypsin deficiency (AATD) is an inherited condition that predisposes individuals to an increased risk of developing lung and liver disease. Even though AATD is one of the most widespread inherited diseases in Caucasian populations, only a minority of affected individuals has been detected. Whereas methods have been validated for AATD testing, there is no universally-established algorithm for the detection and diagnosis of the disorder. In order to compare different methods for diagnosing AATD, we carried out a systematic review of the literature on AATD diagnostic algorithms.

METHODS

Complete biochemical and molecular analyses of 5,352 samples processed in our laboratory were retrospectively studied using each of the selected algorithms.

RESULTS

When applying the diagnostic algorithms to the same samples, the frequency of False Negatives varied from 1.94 to 12.9%, the frequency of True Negatives was 62.91% for each algorithm and the frequency of True Positives ranged from 24.19 to 35.15%. We, therefore, highlighted some differences among Negative Predictive Values, ranging from 0.83 to 0.97. Accordingly, the sensitivity of each algorithm ranged between 0.61 and 0.95. We also postulated 1.108 g/L as optimal AAT cut-off value, in absence of inflammatory status, which points to the possible presence of genetic AATD.

CONCLUSIONS

The choice of the diagnostic algorithm has a significant impact on the correct diagnosis of AATD, which is essential for appropriate treatment and medical care. The fairly large number of possible false negative diagnoses revealed by the present paper should also warn clinicians of negative results in patients with clinically-suspected AATD.

The patient perspective of alpha-1 antitrypsin deficiency: disease burden and unmet needs

Alpha-1 antitrypsin deficiency (AATD) is one of the most frequent rare diseases in Europe and may result in serious lung disease and/or liver disease in adults. People with this condition have a much lower level than normal of the protective protein alpha-1 antitrypsin (AAT) in their blood. AAT protects the body from a powerful enzyme called neutrophil elastase. AATD is an inherited condition that is caused by mutations in the SERPINA1 gene, which can lead to a shortage of AAT or an abnormal form of the protein that cannot control neutrophil elastase. The SERPINA1 gene has more than 100 variants, coded for by two alleles (different versions of the same gene). PiMM is the normal allele, while PiMZ has one normal and one defective allele and PiZZ is the most common allele that causes AATD. The signs and symptoms of the condition and the age at which they appear vary significantly among individuals. The heterogeneity of the clinical picture of AATD depends on a variety of genetic and external aspects. Environmental factors, such as exposure to tobacco smoke, chemicals and dust, probably impact the severity of AATD-associated lung disease.

Three people with alpha-1 antitrypsin deficiency (AATD) share their experiences of living with this rare, genetic condition. They reflect on living with AATD and its impact on their lives including inequality of access to treatment across Europe.https://bit.ly/3rrYS9s

Knockdown of Alpha-1 Antitrypsin with antisense oligonucleotide does not exacerbate smoke induced lung injury

Alpha-1 Antitrypsin (AAT) is a serum protease inhibitor that regulates increased lung protease production induced by cigarette smoking. Mutations in the Serpina1 gene cause AAT to form hepatoxic polymers, which can lead to reduced availability for the protein’s primary function and severe liver disease. An AAT antisense oligonucleotide (ASO) was previously identified to be beneficial for the AATD liver disease by blocking the mutated AAT transcripts. Here we hypothesized that knockdown of AAT aggravates murine lung injury during smoke exposure and acute exacerbations of chronic obstructive pulmonary disease (COPD). C57BL/6J mice were randomly divided into 4 groups each for the smoking and smoke-flu injury models. The ASO and control (No-ASO) were injected subcutaneously starting with smoking or four days prior to influenza infection and then injected weekly at 50 mg/kg body weight. ASO treatment during a 3-month smoke exposure significantly decreased the serum and lung AAT expression, resulting in increased Cela1 expression and elastase activity. However, despite the decrease in AAT, neither the inflammatory cell counts in the bronchoalveolar lavage fluid (BALF) nor the lung structural changes were significantly worsened by ASO treatment. We observed significant differences in inflammation and emphysema due to smoke exposure, but did not observe an ASO treatment effect. Similarly, with the smoke-flu model, differences were only observed between smoke-flu and room air controls, but not as a result of ASO treatment. Off-target effects or compensatory mechanisms may account for this finding. Alternatively, the reduction of AAT with ASO treatment, while sufficient to protect from liver injury, may not be robust enough to lead to lung injury. The results also suggest that previously described AAT ASO treatment for AAT mutation related liver disease may attenuate hepatic injury without being detrimental to the lungs. These potential mechanisms need to be further investigated in order to fully understand the impact of AAT inhibition on protease-antiprotease imbalance in the murine smoke exposure model.

Alpha1-antitrypsin deficiency and asthma

PURPOSE OF REVIEW

The aim of the article is to highlight the association between α1-antitrypsin deficiency (AATD) and asthma.

RECENT FINDINGS

AATD is one of the most common and underrecognized autosomal disorders associated with an increased risk of developing liver and lung diseases. An association between α1-antitrypsin and asthma has been suggested, especially with severe forms of this disease. Many studies have shown an increased prevalence of asthma in the α1-antitrypsin-deficient population overtime (4-38%). The biological mechanism underlying these two conditions and able to bind them has not yet been well investigated. As α1-antitrypsin is the main inhibitor of the serine proteinase and it is an important anti-inflammatory protein with pronounced immunomodulatory activities, it can be hypothesized that the link between AATD and asthma might be represented by the elastase/antielastase imbalance and the proinflammatory effect that occurs because of the reduction of this protein.

SUMMARY

There is a strong need for further researches to better understand the molecular mechanisms binding AATD and asthma. It is also recommendable to screen for AATD, late-onset asthma patients, and/or those with not fully reversible airways obstruction.

Gene coexpression networks reveal novel molecular endotypes in alpha-1 antitrypsin deficiency

BACKGROUND

Alpha-1 antitrypsin deficiency (AATD) is a genetic condition that causes early onset pulmonary emphysema and airways obstruction. The complete mechanisms via which AATD causes lung disease are not fully understood. To improve our understanding of the pathogenesis of AATD, we investigated gene expression profiles of bronchoalveolar lavage (BAL) and peripheral blood mononuclear cells (PBMCs) in AATD individuals.

METHODS

We performed RNA-Seq on RNA extracted from matched BAL and PBMC samples isolated from 89 subjects enrolled in the Genomic Research in Alpha-1 Antitrypsin Deficiency and Sarcoidosis (GRADS) study. Subjects were stratified by genotype and augmentation therapy. Supervised and unsupervised differential gene expression analyses were performed using Weighted Gene Co-expression Network Analysis (WGCNA) to identify gene profiles associated with subjects' clinical variables. The genes in the most significant WGCNA module were used to cluster AATD individuals. Gene validation was performed by NanoString nCounter Gene Expression Assay.

RESULT

We observed modest effects of AATD genotype and augmentation therapy on gene expression. When WGCNA was applied to BAL transcriptome, one gene module, ME31 (2312 genes), correlated with the highest number of clinical variables and was functionally enriched with numerous immune T-lymphocyte related pathways. This gene module identified two distinct clusters of AATD individuals with different disease severity and distinct PBMC gene expression patterns.

CONCLUSIONS

We successfully identified novel clusters of AATD individuals where severity correlated with increased immune response independent of individuals' genotype and augmentation therapy. These findings may suggest the presence of previously unrecognised disease endotypes in AATD that associate with T-lymphocyte immunity and disease severity.

Alpha-1 antitrypsin deficiency-associated panniculitis

BACKGROUND

Panniculitis represents a rare and potentially lethal manifestation of alpha-1 antitrypsin deficiency (AATD). Evidence regarding management is limited to case reports and small case series. We sought to clarify typical features and investigation of AATD-associated panniculitis and assess the evidence regarding therapeutic options.

SEARCH METHODOLOGY

Articles and abstracts published between 1970 and 2020 were identified by searches of MEDLINE, PubMed, and secondary searches of references from relevant articles using the search terms "panniculitis," "alpha-1," "antitrypsin," "deficiency," and "Weber-Christian."

FINDINGS

We identified 117 cases of AATD-associated panniculitis. In 1 series, AATD was present in 15% of all cases of biopsy-proven panniculitis. Failure to achieve clinical response was seen in all instances of systemic steroid use. Dapsone, although effective and accessible, is frequently associated with failure to achieve remission. In these instances, intravenous AAT augmentation therapy generally resulted in response.

CONCLUSIONS

AATD may be more prevalent among patients presenting with panniculitis than previously thought. Patients presenting with panniculitis and systemic illness show high mortality risk. Although most cases are associated with the severe ZZ-genotype, moderate genotypes may also predispose to panniculitis. Dapsone remains the most cost-effective therapeutic option, whereas intravenous AAT augmentation remains the most efficacious. Finally, glucocorticoids appear ineffective in this setting.

Clinical presentations of four patients with rare Alpha 1 Antitrypsin variants identified in a single US center

Alpha 1 Antitrypsin Deficiency (AATD) is a rare condition primarily associated with lung complications and liver disease. As disease symptoms are similar to those in other respiratory conditions, patients generally experience long delays before receiving an accurate diagnosis and treatment. AATD results from mutations in the SERPINA1 gene that encodes Alpha 1 Antitrypsin (AAT). Over 500 single-nucleotide variants have been reported in mutation databases; however, there is increasing interest in the clinical significance of rare and novel SERPINA1 variants. In this case series of four patients from a single US center, next-generation sequencing (NGS) was used to guide AATD diagnosis. Four distinct rare variants of SERPINA1 (P289S; I50N; E204K; H262Y) were identified, three of which were found in patients with advanced chronic obstructive pulmonary disease (COPD)/emphysema. Computational modeling predicted these mutations to have potentially deleterious effects, a finding supported by AAT levels that were comparable with those seen in individuals heterozygous for the most common deficiency allele (PI*MZ). The remaining mutation (E204K) was found in a patient with a cerebral aneurysm; potential links between SERPINA1 variants and neurological conditions, such as cerebral aneurysm and arterial dissections, have been previously reported in individuals with heterozygous AATD phenotypes (PI*MS and PI*MZ). Novel and rare variants, often not detected by basic AATD diagnostic tests, have the potential to contribute to the development of COPD and emphysema. Detection of these variants can be enhanced by NGS, and modeling techniques can help determine if variants are pathogenic, thereby enabling a quicker, more accurate AATD diagnosis.

The Clinical Utility of Determining the Allelic Background of Mutations Causing Alpha-1 Antitrypsin Deficiency: The Case with the Null Variant Q0(Mattawa)/Q0(Ourém)

Background

Alpha-1 antitrypsin deficiency (AATD) is caused by genetic variants in the SERPINA1 gene conferring risk of developing emphysema. The clinical expression of AATD-related emphysema mostly occurs in carriers of 2 deficient alleles. By DNA sequencing of SERPINA1, numerous rare variants have been identified. Clarifying whether 2 mutations observed in 1 patient are on the same or distinct alleles has obvious clinical implications.

Methods

We studied 7 carriers of a rare variant, Leu353Phe_fsTer24, known to lead to undetectable serum levels of AAT. Two of them were also carriers of the S or Z allele. We developed an allele-specific DNA sequencing method to characterize the allelic background of the Leu353Phe_fsTer24 variant.

Results

The Leu353Phe_fsTer24 variant was transmitted on the same allele as the M3 variant (E376D) in all patients. This mutation is thus named Q0_Ourém on the conventional PI system. We demonstrated that individuals harboring the E264V (S) and E342K (Z) mutations had them on distinct alleles from Q0_Ourém and are, thus, compound heterozygotes. The 7 Q0_Ourém carriers had AAT levels ranging from 0.18g/l to 0.82g/l. The lowest AAT serum levels were observed in compound heterozygotes (S/Q0_Ourém and Z/Q0_Ourém) suggesting higher risk of developing emphysema.

Conclusion

For the 7 patients, Leu353Phe_fsTer24 is transmitted on the M3 background and they are, thus, carriers of the Q0_Ourém allele. Allele-specific DNA sequencing was useful to distinguish 1 or 2 deficient alleles in carriers of 2 mutations. In rare cases, this method is important to understand the clinical significance of genetic variants found in SERPINA1.

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

This review summarizes the current research and outlooks regarding the obstacles to diagnosing and treating early alpha-1-antitrypsin deficiency (AATD). It draws on prior systematic reviews and expert surveys to discover precisely what difficulties exist in early diagnosis and treatment of AATD and elucidate potential solutions to ease these difficulties. The perceived rarity of AATD may translate to a condition poorly understood by primary care physicians, and even many respiratory physicians, which results in opportunities for diagnosis being missed, especially in mild or asymptomatic patients. There are diagnostic techniques involving biomarkers and home testing methods which could improve the rate of early diagnosis. With respect to treatment, AATD involves treating two separate pathologies, lung disease and liver disease. The only specific AATD treatment, augmentation therapy, has proven ability in treating lung disease but not liver disease. Alpha-1-antitrypsin (AAT) synthesized in the liver can form damaging polymers that also result in reduced circulating AAT levels and, whilst liver transplantation is used to effectively treat AATD, it is inappropriate in early disease. Novel therapeutic areas such as gene editing and increasing autophagy are therefore being researched as future treatments. Ultimately, diagnosis and treatment are intrinsically linked in AATD, with earlier diagnosis leading to better treatment options and thus better patient outcomes.

Identification of Variants in Alpha-1-Antitrypsin by High Resolution Melting

BACKGROUND

Alpha-1-antitrypsin deficiency (AATD) is one of the most common hereditary disorders occurring in populations of European origin and is due to variants in SERPINA1, which encodes a protease inhibitor of neutrophil elastase, limiting lung damage from this enzyme. The World Health Organization has recommended that individuals with chronic obstructive pulmonary disease and asthma be tested for AATD. The development of inexpensive and simple genetic testing will help to meet this goal.

METHODS

Primers and synthetic SERPINA1 gene fragments (gBlocks) were designed for 5 AATD-associated variants. PCR was run on a CFX96 Thermal Cycler with High Resolution Melting (HRM) capacity and data analyzed using the supplied HRM-analysis software. Genomic DNA from individuals (n = 86) genotyped for the S and Z variants were used for validation. HRM-analysis was performed on 3 additional samples with low alpha-1-antitrypsin levels inconsistent with the genotype determined in our clinical laboratory.

RESULTS

Unique normalized melt curve and difference curve patterns were identified for the AAT variants Z, S, I, F, and MMalton using gBlocks. Similar curve shapes were seen when these primers were used to analyze the gDNA samples. HRM identified the genotypes of the gDNA correctly with 100% concordance. The curve shapes of some samples did not match the melting patterns of the targeted variant. Sequencing was used to identify the variants, including rare AATD variants c.1108_1115delinsAAAAACA (p.Glu370Lysfs*31) and c.1130dup (p.Leu377fs).

CONCLUSION

We developed a rapid and inexpensive HRM-analysis method for genotyping of Z, S, MMalton, I, and F variants that was also capable of detecting other variants.

High-resolution ex vivo NMR spectroscopy of human Z α1-antitrypsin

Genetic mutations predispose the serine protease inhibitor α1-antitrypsin to misfolding and polymerisation within hepatocytes, causing liver disease and chronic obstructive pulmonary disease. This misfolding occurs via a transiently populated intermediate state, but our structural understanding of this process is limited by the instability of recombinant α1-antitrypsin variants in solution. Here we apply NMR spectroscopy to patient-derived samples of α1-antitrypsin at natural isotopic abundance to investigate the consequences of disease-causing mutations, and observe widespread chemical shift perturbations for methyl groups in Z AAT (E342K). By comparison with perturbations induced by binding of a small-molecule inhibitor of misfolding we conclude that they arise from rapid exchange between the native conformation and a well-populated intermediate state. The observation that this intermediate is stabilised by inhibitor binding suggests a paradoxical approach to the targeted treatment of protein misfolding disorders, wherein the stabilisation of disease-associated states provides selectivity while inhibiting further transitions along misfolding pathways.

Improving the Lives of Patients with Alpha-1 Antitrypsin Deficiency

Alpha-1 Antitrypsin Deficiency (AATD) is a rare genetic condition that predisposes patients to lung and liver disease and is often underdiagnosed due to incomplete diagnosis of chronic obstructive pulmonary disease (COPD) and asthma. Improvements in physician awareness have been made, but better strategies for both diagnosis and management are still required. The only current disease-modifying therapy for AATD is the infusion of the missing Alpha-1 Antitrypsin (AAT) protein, which can slow progression of emphysema. However, AAT treatment can impact patient freedom and quality of life due to the need for weekly intravenous infusions. A symposium was held to discuss patient-centric aspects of care that have impact on the lives of patients with AATD, including exacerbations of their lung disease, self-administration of intravenous AAT therapy and pulmonary rehabilitation. Intravenous self-infusion of drugs is an established treatment strategy for patients with a variety of conditions and can improve patient quality of life, freedom and mental well-being. Experience from these areas show that patients typically manage their treatment well and without complications. When applied to AATD, training patients to self-infuse therapy can be successful, but formal guidelines would be beneficial. In addition to pharmacological intervention, individualized pulmonary rehabilitation, exercise and educational programs can encourage health-enhancing patient behavior and further improve patient quality of life. However, differences in skeletal muscle adaptations to pulmonary rehabilitation exercise regimens have been observed between patients with AATD and non-AATD COPD, highlighting the need to develop training programs specifically designed for patients with AATD.

Serum Levels of Glutamate-Pyruvate Transaminase, Glutamate-Oxaloacetate Transaminase and Gamma-Glutamyl Transferase in 1494 Patients with Various Genotypes for the Alpha-1 Antitrypsin Gene

Background: Patients with liver disease associated with alpha-1 antitrypsin deficiency (AATD) are homozygous for the Z mutation, leading to chronic liver damage. Objective: To assess the serum levels of glutamate-oxaloacetate transaminase (GOT), glutamate-pyruvate transaminase (GPT), and gamma-glutamyl transpeptidase (GGT) in patients with different genotypes for the alpha-1 antitrypsin (AAT) gene. Methods: Patients (n = 1494) underwent genotyping of the SERPINA1 gene, together with a determination of AAT and GOT and GPT and GGT transaminase levels. Patients with a deficient allele (n = 476) and with a normal genotype were compared. Results: A statistically significant association was found between deficient genotypes and GOT (p < 0.0003), GPT (p < 0.002), and GGT (p < 0.006). Comparing GOT levels in patients with PI*Z deficient variant versus those with normal genotype, an odds ratio (OR) of 2.72 (CI: 1.5–4.87) (p < 0.0005) was obtained. This finding was replicated with the PI*Z allele and the GPT values (OR = 2.31; CI: 1.45–3.67; p < 0.0003). In addition, a statistically significant association was found between liver enzymes and AAT values. Conclusion: The PI*Z allele seemed to be a risk factor for the development of liver damage. AAT deficient genotypes were associated with GOT, GPT, and GGT altered values. Low AAT levels were associated with high GPT and GGT levels.

Longitudinal Outcomes in Young Patients with Alpha-1-Antitrypsin Deficiency with Native Liver Reveal that Neonatal Cholestasis is a Poor Predictor of Future Portal Hypertension

OBJECTIVES

To identify predictors of portal hypertension, liver transplantation, and death in North American youth with alpha-1-antitrypsin (AAT) deficiency, and compare with patients with AAT deficiency elsewhere.

STUDY DESIGN

The Childhood Liver Disease Research Network Longitudinal Observational Study of Genetic Causes of Intrahepatic Cholestasis is a prospective, cohort study of pediatric cholestatic liver diseases, including AAT deficiency, enrolling PIZZ and PISZ subjects 0-25 years of age seen since November 2007 at 17 tertiary care centers in the US and Canada. Data from standard-of-care baseline and annual follow-up visits were recorded from medical records, history, physical examination, and laboratory studies. Participants with portal hypertension were identified based on data collected.

RESULTS

We enrolled 350 participants (60% male) with a native liver; 278 (79%) entered the cohort without portal hypertension and 18 developed portal hypertension during follow-up. Thirty participants required liver transplantation; 2 patients died during 1077 person-years of follow-up. There was no difference in participants with or without preceding neonatal cholestasis progressing to transplantation or death during the study (12% vs 7%; P = .09), or in experiencing portal hypertension (28% vs 21%; P = .16); the hazard ratio for neonatal cholestasis leading to portal hypertension was P = .04. Development of portal hypertension was associated with a reduced height Z-score.

CONCLUSIONS

Portal hypertension in youth with AAT deficiency impacts growth measures. Progression to liver transplantation is slow and death is rare, but the risk of complications and severe liver disease progression persists throughout childhood. A history of neonatal cholestasis is a weak predictor of severe disease.

The Distribution of Alpha-1 Antitrypsin Genotypes Between Patients with COPD/Emphysema, Asthma and Bronchiectasis

Purpose

Alpha-1-antitrypsin deficiency (AATD) is a rare hereditary condition characterized by low circulating levels of alpha-1antitrypsin (AAT). While the association between AATD and COPD/emphysema is undisputed, the association between AATD and asthma or bronchiectasis is still a matter of debate.

Aims and Objectives

Our study aimed to investigate the distribution of AAT genotypes between patients with COPD/emphysema, asthma and bronchiectasis. To back up the diagnostic labels, we described symptoms associated with the diagnosis.

Methods

Between September 2003 and March 2020, 29,465 testing kits (AlphaKit®) were analyzed in the AAT laboratory, University of Marburg, Germany. The diagnosis of AATD has been made based on the measurements of AAT serum levels, followed by genotyping, phenotyping or whole gene sequencing depending on the availability and/or the need for more detailed interpretation of the results. The respiratory symptoms were recorded as well.

Results

Regarding the distribution of the wild type allele M and the most frequent mutations S (E264V) and Z (E342K), no significant differences could be found between COPD/emphysema [Pi*MM (58.24%); Pi*SZ (2.49%); Pi*ZZ (9.12%)] and bronchiectasis [Pi*MM (59.30%) Pi*SZ (2.81%); Pi*ZZ (7.02%)]. When COPD/emphysema and bronchiectasis were recorded in the same patient, the rate of Pi* ZZ (14.78%) mutations was even higher. Asthma patients exhibited significantly less deficient genotypes [Pi*MM (54.81%); Pi*SZ (2%); Pi*ZZ (2.77%)] than two other groups. Associated respiratory symptoms confirmed the diagnosis.

Conclusion

COPD/emphysema and bronchiectasis, but not asthma patients, exhibit higher frequency of AATD genotypes. Our data suggest that AATD testing should be offered to patients with COPD/emphysema and bronchiectasis.

Alpha-1 antitrypsin deficiency: an update on clinical aspects of diagnosis and management

Clinical heterogeneity has been demonstrated in alpha-1 antitrypsin deficiency (AATD), such that clinical suspicion plays an important role in its diagnosis. The PiZZ genotype is the most common severe deficiency genotype and so tends to result in the worst clinical presentation, hence it has been the major focus of research. However, milder genotypes, especially PiSZ and PiMZ, are also linked to the development of lung and liver disease, mainly when unhealthy behaviors are present, such as smoking and alcohol use. Monitoring and managing AATD patients remains an area of active research. Lung function tests or computed tomography (CT) densitometry may allow physicians to identify progressive disease during follow up of patients, with a view to decision making about AATD-specific therapy, like augmentation therapy, or eventually surgical procedures such as lung volume reduction or transplant. Different types of biological markers have been suggested for disease monitoring and therapy selection, although most need further investigation. Intravenous augmentation therapy reduces the progression of emphysema in PiZZ patients and is available in many European countries, but its effect in milder deficiency is less certain. AATD has also been suggested to represent a risk factor and trigger for pulmonary infections, like those induced by mycobacteria. We summarize the last 5-10 years' key findings in AATD diagnosis, assessment, and management, with a focus on milder deficiency variants.

Alpha-1 antitrypsin deficiency is significantly associated with atopy in asthmatic patients

BACKGROUND

Although the etiology and disease mechanisms of asthma and alpha-1 antitrypsin deficiency (AATD) are distinct, several reports indicate that asthma is common in AATD patients, however the relationships between asthma and AATD are poorly described in the literature.

OBJECTIVES

The aim of the study was to investigate in a cohort of outpatients affected by mild to moderate asthma the clinical features that may differentiate asthmatic patients with and without mutation on SERPINA1 gene.

METHODS

Seven hundred thirty-five asthmatic outpatients underwent quantitative analysis of the serum level of alpha-1antitrypsin. According to the literature only sixty-seven out of seven hundred thirty-five asthmatic patients were submitted to genetic analysis to identify AATD and non-AATD subjects. Fifty-eight patients were studied. Clinical and functional data, including lung function, atopy and bronchial hyperactivity, were recorded.

RESULTS

The fifty-eight asthmatic patients were divided in AATD patients (n = 22) and non AATD patients (n = 36), according to genotype. The presence of atopy was significantly higher in patients with AATD than in those without AATD (91% vs. 64%; p = 0.031). AATD patients reported allergic manifestations more than non AATD patients (77% vs. 47%; p = 0.030).

CONCLUSION

Our study shows that the presence of atopy in asthmatic patients with AATD is significantly higher than in asthmatic patients without gene mutation. In addition, a higher percentage of AATD patients self-reported allergic manifestations. No significant differences in respiratory symptoms, physical examination, disease severity or inflammation markers were found between AATD patients and non AATD patients.

Comorbidity Associations with AATD Among Commercially Insured and Medicare Beneficiaries with COPD in the US

Introduction

Alpha-1 antitrypsin deficiency (AATD) is often not identified in patients with chronic obstructive pulmonary disease (COPD) until advanced stages of disease, despite the availability of genetic testing. While clinical practice guidelines provide recommendations on patients who should be tested, more refined algorithms are needed to identify COPD patients who are likely candidates for AATD testing and to prevent delays in diagnosis and treatment. The objective of this study was to identify comorbid associations with AATD among patients diagnosed with COPD in the United States.

Methods

Using data from the 2012–2017 PharMetrics Plus Administrative Claims Database and 2011–2014 Medicare Fee for Service 5% Sample, patients with COPD (ICD-9-CM: 491.xx, 492.xx, or 496, ICD-10-CM J41, J42, J43, J44) and AATD (ICD-9-CM: 273.4, ICD-10-CM: E88.01) were identified. Patient demographic and diagnostic characteristics were assessed. Logistic regression models were developed to identify significant predictors of AATD.

Results

A cohort of 344,528 Medicare beneficiaries with COPD (of which 302 (0.09%) also had two diagnoses of AATD) and a cohort of 340,259 commercially insured patients with COPD (of which 1076 (0.3%) also had a diagnosis of AATD) were constructed. Associations with AATD identified in both models included ICD-9-CM and ICD-10-CM codes for chronic pulmonary heart disease, chronic liver disease and cirrhosis, and liver transplant.

Discussion

Significant associations with a diagnosis of AATD among patients with COPD were consistently represented in each of the datasets evaluated, which suggests meaningful comorbidity implications in AATD patients. These findings reinforce the need to test individuals with COPD for AATD as early as possible to help reduce the development of associated comorbid conditions.

<p>Evaluation of the Small Airways in Patients with Chronic Obstructive Pulmonary Disease and Alpha-1 Antitrypsin Deficiency</p>

Introduction

Small airways are not evaluated with traditional pulmonary function tests. The aim of this study was to evaluate the small airways in patients with chronic obstructive pulmonary disease (COPD) with a nitrogen washout test and to verify whether there is a difference between patients with COPD due to smoking and those with COPD due to alpha-1 antitrypsin mutation.

Methods

Sixteen patients with mutation in the SERPINA1 gene and 45 patients with no mutation were included in this cross-sectional study. All pulmonary function tests, including the single breath nitrogen washout test, were performed for all patients and alpha-1 antitrypsin dosage was assessed with immunonephelometry.

Results

A comparison of patients with COPD due to smoking and those with COPD due to smoking and mutation revealed a significant difference in closure volume (%), which was the poorest in the mutation group. In the group with COPD and mutation, there was an inverse correlation between smoking and closure volume (%). We also verified that similar to forced expiratory volume in the first second (FEV1), the phase III slope (%) and ΔN2 750–1250 mL (%) could be used to differentiate the severity of airflow limitation.

Conclusion

Our results suggest that both variables, phase III slope and the ΔN2 750–1250 mL (%), could be related to COPD severity. Therefore, alterations at the distribution of the location of the emphysema could alter the results of closer volume and that the nitrogen washout test is more sensitive when compared to traditional pulmonary function test in evaluating COPD patients.

PredictAAT: Accounting for Inflammation in the Diagnosis of Alpha 1 Antitrypsin Deficiency

Alpha 1 antitrypsin deficiency (AATD) is a rarely diagnosed hereditary condition characterized by low alpha 1 antitrypsin (AAT) levels, which can lead to early-onset emphysema due to accelerated degradation of lung tissue. Similar to C-reactive protein (CRP), AAT is an acute phase reactant, meaning that blood levels rise in response to inflammation, injury or infection. Testing AAT levels is essential in the diagnosis of AATD; however, the presence of inflammation at the time of AATD testing can provide a false 'normal' level reading of the patient's baseline AAT levels. Researchers from a US-wide screening program for AATD found that a large number of individuals with AATD variants (particularly with the PI*MZ genotype) presented with elevated CRP levels (≥5 mg/L), suggesting the presence of inflammation. Using a series of calculations, the relationship between AAT and CRP levels was characterized and found to be genotype specific. We have developed a publicly available, easy-to-use online calculator (PredictAAT) that enables the instant calculation of predicted baseline AAT levels in patients exhibiting elevated CRP levels that accounts for specific AATD genotype. There is a need to raise awareness of the importance of simultaneous determination of AAT and CRP levels to aid the accurate diagnosis of patients with AATD. The PredictAAT calculator is therefore a valuable tool for physicians to enhance early disease diagnosis and individualize treatment.

Gene therapy for alpha 1-antitrypsin deficiency with an oxidant-resistant human alpha 1-antitrypsin

Alpha 1-antitrypsin (AAT) deficiency, a hereditary disorder characterized by low serum levels of functional AAT, is associated with early development of panacinar emphysema. AAT inhibits serine proteases, including neutrophil elastase, protecting the lung from proteolytic destruction. Cigarette smoke, pollution, and inflammatory cell–mediated oxidation of methionine (M) 351 and 358 inactivates AAT, limiting lung protection. In vitro studies using amino acid substitutions demonstrated that replacing M351 with valine (V) and M358 with leucine (L) on a normal M1 alanine (A) 213 background provided maximum antiprotease protection despite oxidant stress. We hypothesized that a onetime administration of a serotype 8 adeno-associated virus (AAV8) gene transfer vector coding for the oxidation-resistant variant AAT (A213/V351/L358; 8/AVL) would maintain antiprotease activity under oxidant stress compared with normal AAT (A213/M351/M358; 8/AMM). 8/AVL was administered via intravenous (IV) and intrapleural (IPL) routes to C57BL/6 mice. High, dose-dependent AAT levels were found in the serum and lung epithelial lining fluid (ELF) of mice administered 8/AVL or 8/AMM by IV or IPL. 8/AVL serum and ELF retained serine protease–inhibitory activity despite oxidant stress while 8/AMM function was abolished. 8/AVL represents a second-generation gene therapy for AAT deficiency providing effective antiprotease protection even with oxidant stress.

A gene transfer-based therapeutic to deliver oxidant-resistant alpha 1-antitrypsin (AAT) protects mice with AAT deficiency from lung destruction.

Implications of a Change of Paradigm in Alpha1 Antitrypsin Deficiency Augmentation Therapy: From Biochemical to Clinical Efficacy

Ever since the first studies, restoring proteinase imbalance in the lung has traditionally been considered as the main goal of alpha1 antitrypsin (AAT) replacement therapy. This strategy was therefore based on ensuring biochemical efficacy, identifying a protection threshold, and evaluating different dosage regimens. Subsequently, the publication of the results of the main clinical trials showing a decrease in the progression of pulmonary emphysema has led to a debate over a possible change in the main objective of treatment, from biochemical efficacy to clinical efficacy in terms of lung densitometry deterioration prevention. This new paradigm has produced a series controversies and unanswered questions which face clinicians managing AAT deficiency. In this review, the concepts that led to the approval of AAT replacement therapy are reviewed and discussed under a new prism of achieving clinical efficacy, with the reduction of lung deterioration as the main objective. Here, we propose the use of current knowledge and clinical experience to face existing challenges in different clinical scenarios, in order to help clinicians in decision-making, increase interest in the disease, and stimulate research in this field.

Chronic Obstructive Pulmonary Disease

Chronic obstructive pulmonary disease (COPD) is characterized by persistent respiratory symptoms and progressive airflow obstruction. Tobacco smoking is the leading cause but not the only one. A postbronchodilator FEV₁-FVC ratio less than 0.70 is required for a diagnosis of COPD. Inhaler therapy is the backbone of treatment and should be complemented by a multifaceted management strategy that includes counseling and pharmacotherapy for smoking cessation, pulmonary rehabilitation, treatment of comorbidities, administration of influenza and pneumococcal immunizations, and prescription of long-term oxygen therapy in hypoxemic patients.

Paediatric cholestatic liver disorders for the adult gastroenterologist: a practical guide

With improvements in the outcomes for cholestatic liver diseases that present in childhood, increasing numbers of patients will require ongoing care as adults. The recent advances in management options coupled with the fact that each adult physician will have a limited number of patients with these conditions means there is a need for those in adult services to develop expertise in these conditions that were historically the domain of paediatrics. This review provides an overview of the most common paediatric cholestatic liver diseases and outlines the clinical manifestations and potential complications, and identifies key management issues unique to each condition for effective ongoing care of these patients.

Alpha1-Antitrypsin Deficiency: A Cause of Chronic Liver Disease

Alpha1-antitrypsin deficiency (A1ATD) is an inherited cause of chronic liver disease. It is inherited in an autosomal codominant pattern with each inherited allele expressed in the formation of the final protein, which is primarily produced in hepatocytes. The disease usually occurs in pediatric and elderly populations. The disease occurs with the accumulation of abnormal protein polymers within hepatocytes that can induce liver injury and fibrosis. It is a commonly under-recognized and underdiagnosed condition. Patients diagnosed with the disease should be regularly monitored for the development of liver disease. Liver transplant is of proven benefit in A1ATD liver disease.

Intrahepatic heteropolymerization of M and Z alpha-1-antitrypsin

The α-1-antitrypsin (or alpha-1-antitrypsin, A1AT) Z variant is the primary cause of severe A1AT deficiency and forms polymeric chains that aggregate in the endoplasmic reticulum of hepatocytes. Around 2%-5% of Europeans are heterozygous for the Z and WT M allele, and there is evidence of increased risk of liver disease when compared with MM A1AT individuals. We have shown that Z and M A1AT can copolymerize in cell models, but there has been no direct observation of heteropolymer formation in vivo. To this end, we developed a monoclonal antibody (mAb2H2) that specifically binds to M in preference to Z A1AT, localized its epitope using crystallography to a region perturbed by the Z (Glu342Lys) substitution, and used Fab fragments to label polymers isolated from an MZ heterozygote liver explant. Glu342 is critical to the affinity of mAb2H2, since it also recognized the mild S-deficiency variant (Glu264Val) present in circulating polymers from SZ heterozygotes. Negative-stain electron microscopy of the Fab2H2-labeled liver polymers revealed that M comprises around 6% of the polymer subunits in the MZ liver sample. These data demonstrate that Z A1AT can form heteropolymers with polymerization-inert variants in vivo with implications for liver disease in heterozygous individuals.

Prevalence of α1-antitrypsin PiZZ genotypes in patients with COPD in Europe: a systematic review

The percentage of α₁-antitrypsin protease inhibitor ZZ (PiZZ) genotypes in patients with COPD is controversial, with large differences among various studies. We aimed to estimate the prevalence of PiZZ in COPD patients from 20 European countries with available data, according to the number of PiZZ and COPD individuals in each country.

A systematic review was conducted to select European countries with reliable data on the prevalence of PiZZ and COPD. We created a database with the following data: 1) total population and population aged ≥40 years according to the Eurostat database; 2) number and 95% CI of PiZZ patients aged ≥40 years; 3) application of a conversion factor of genetic penetrance of 60%; 4) number of COPD individuals, with 95% CI, aged ≥40 years; and 5) calculation of the PiZZ/COPD ratio. Finally, results were presented using an Inverse Distance Weighted Interpolation map.

We found 36 298 (95% CI 23 643–56 594) PiZZ individuals at high risk and 30 849 709 (95% CI 21 411 293–40 344 496) COPD patients, with a PiZZ/COPD ratio of 0.12% (range 0.08–0.24%), and a prevalence of 1 out of 408 in Northern, 1 out of 944 in Western, 1 out of 1051 in Central, 1 out of 711 in Southern, and 1 out of 1274 in Eastern Europe.

These data may be useful to plan strategies for future research and diagnosis, and to rationalise the available therapeutic resources.

There is a significant number of PiZZ individuals at high risk of COPD, as well as an impressive number of patients with COPD in Europe. The ratio between PiZZ and COPD ranges between 0.08% and 0.24%, with wide differences among countries.https://bit.ly/2VrOzUv

A Highly Phenotyped Open Access Repository of Alpha-1 Antitrypsin Deficiency Pluripotent Stem Cells

Individuals with the genetic disorder alpha-1 antitrypsin deficiency (AATD) are at risk of developing lung and liver disease. Patient induced pluripotent stem cells (iPSCs) have been found to model features of AATD pathogenesis but only a handful of AATD patient iPSC lines have been published. To capture the significant phenotypic diversity of the patient population, we describe here the establishment and characterization of a curated repository of AATD iPSCs with associated disease-relevant clinical data. To highlight the utility of the repository, we selected a subset of iPSC lines for functional characterization. Selected lines were differentiated to generate both hepatic and lung cell lineages and analyzed by RNA sequencing. In addition, two iPSC lines were targeted using CRISPR/Cas9 editing to accomplish scarless repair. Repository iPSCs are available to investigators for studies of disease pathogenesis and therapeutic discovery.

Decreased Risk of Ischemic Heart Disease in Individuals with Severe Alpha 1-Antitrypsin Deficiency (PiZZ) in Comparison with the General Population

Background

Severe alpha-1-antitrypsin deficiency (AATD) is an established risk factor for chronic obstructive pulmonary disease (COPD) and liver disease, but the effect on the incidence of ischemic heart disease (IHD) is not well known. The aim was to evaluate the risk of incident IHD in patients with severe AATD compared with a random sample of the general population, with known smoking habits.

Methods

AAT-deficient individuals, phenotype PiZZ (n=1545), were included in the Swedish National AATD Register. Controls (n=5883) were selected from population-based cohorts in Northern Sweden. Data on IHD and comorbidities were obtained by nationwide cross-linkage with the Swedish National Patient Register. Risk factors for incident IHD were analyzed using Cox regression, adjusted for age, gender, smoking status and the presence of COPD, hypertension, hyperlipidemia and diabetes.

Results

At inclusion, 46% of the PiZZ individuals and 53% of the controls were never-smokers. During follow-up (median 16 years; range 0.2–23), 8% (n=123) of PiZZ individuals and 12% (n=690) of controls developed IHD. The controls had a significantly higher risk for incident IHD than the PiZZ individuals, with adjusted hazard ratio (HR) of 1.8 (95% CI 1.4–2.3). The risk was higher for controls in both ever-smokers (HR 2.1; 95% CI 1.5–2.9) and never-smokers (HR 1.5; 95% CI 1.1–2.2).

Conclusion

PiZZ individuals have a lower risk of developing incident ischemic heart disease than the control subjects with known smoking habits, who had been randomly selected from population-based cohorts.

Clarifying the Risk of Lung Disease in SZ Alpha-1 Antitrypsin Deficiency

Rationale: The ZZ genotype of alpha-1 antitrypsin deficiency (AATD) is associated with chronic obstructive pulmonary disease (COPD), even among never-smokers. The SZ genotype is also considered severe; yet, its effect on lung health remains unclear.Objectives: To determine the effect of SZ-AATD on spirometry compared with a normal-risk population and to determine the effect of smoking cessation in this genotype.Methods: We prospectively enrolled 166 related individuals, removing lung index cases to reduce bias, and compared spirometry between 70 SZ and 46 MM/MS individuals (control subjects). The effect of AAT concentrations on outcomes was assessed in 82 SZ individuals (including lung index cases). Subsequently, we analyzed retrospective SZ registry data to determine the effect of smoking cessation on spirometry decline (n = 60) and plasma anti-neutrophil elastase capacity (n = 20).Measurements and Main Results: No difference between SZ and control never-smokers was seen. Ever smoking was associated with a lower FEV1% predicted (-14.3%; P = 0.0092) and a lower FEV1/FVC ratio (-0.075; P = 0.0041) in SZ-AATD. No association was found between AAT concentration and outcomes for SZ-AATD. Longitudinal analysis of 60 SZ individuals demonstrated that COPD at baseline, but not former smoking or AAT concentrations, predicted greater spirometry decline. Finally, anti-neutrophil elastase capacity did not differ between former smokers and never-smokers (P = 0.67).Conclusions: SZ never-smokers demonstrated no increased risk of COPD, regardless of AAT concentration. Smoking interacts with SZ-AATD to significantly increase airflow obstruction. Former smoking alone is not associated with greater spirometry decline in SZ-AATD, suggesting that cessation attenuates the obstructive process. We found no evidence that the putative protective threshold or AAT concentrations predict risk within the SZ genotype, raising further doubts over the need for intravenous AAT augmentation in this cohort.

Alpha-1 Antitrypsin Deficiency: a Rare Disease?

PURPOSE OF REVIEW

Commonly categorized as a rare disease, alpha-1 antitrypsin deficiency (AATD) is neither rare, when compared to many other genetic disorders, nor an actual disease, but rather a predisposition toward a wide variety of diseases. It is one of the most common genetic disorders which can lead to a spectrum of clinical manifestations, ranging from no symptoms to progressively debilitating systemic disease, most commonly affecting the lung and liver. It is therefore imperative for clinicians to recognize and be familiar with the spectrum of presentations, methods of diagnosis, and clinical management of AATD. It is also imperative for scientists to recognize the potential for progress in the management of this disorder.

RECENT FINDINGS

This review focuses on the current state of knowledge of AATD, including the wide range of presentations, diagnosis, and clinical management. In addition to the clinical implications of severe AATD, we discuss the relevance of heterozygous state with mild or moderate AATD in the development of both lung and liver disease. While our understanding of the multiple roles of alpha-1 antitrypsin (AAT) is on the rise, with appreciation of its immunomodulatory, anti-infective, and anti-inflammatory properties, this knowledge has yet to impact our ability to predict outcomes. We discuss nuances of augmentation therapy and review novel therapeutic approaches currently under investigation. With the expanding knowledge about the complexities of AAT function and its clinical relevance, and with the increasing ability to diagnose early and intervene on AATD, it should be our goal to change the perception of AATD as a correctable inherited disorder rather than a fatal disease.

Clinical considerations in individuals with α1-antitrypsin PI*SZ genotype

α₁-Antitrypsin deficiency (AATD), characterised by reduced levels or functionality of α₁-antitrypsin (AAT), is a significantly underdiagnosed genetic condition that predisposes individuals to lung and liver disease. Most of the available data on AATD are based on the most common, severe deficiency genotype (PI*ZZ); therefore, treatment and monitoring requirements for individuals with the PI*SZ genotype, which is associated with a less severe AATD, are not as clear. Recent genetic data suggest the PI*SZ genotype may be significantly more prevalent than currently thought, due in part to less frequent identification in the clinic and less frequent reporting in registries. Intravenous AAT therapy, the only specific treatment for patients with AATD, has been shown to slow disease progression in PI*ZZ individuals; however, there is no specific evidence for AAT therapy in PI*SZ individuals, and it remains unclear whether AAT therapy should be considered in these patients. This narrative review evaluates the available data on the PI*SZ genotype, including genetic prevalence, the age of diagnosis and development of respiratory symptoms compared with PI*ZZ individuals, and the impact of factors such as index versus non-index identification and smoking history. In addition, the relevance of the putative 11 µM “protective threshold” for AAT therapy and the risk of liver disease in PI*SZ individuals is explored. The purpose of this review is to identify open research questions in this area, with the aim of optimising the future identification and management of PI*SZ individuals.

Individuals with α₁-antitrypsin (AAT) PI*SZ genotype appear to have an increased risk for lung and liver disease, although definitive evidence is lacking; smoking is a major risk factor for lung disease. The role of AAT therapy requires further study.http://bit.ly/2TxxFD0

Alpha 1 "Hereditary Emphysema" Experience: A Patient-Physician Perspective

This article is co-authored by a patient living with alpha-1 antitrypsin deficiency, and her treating physician. The commentary article describes the patient’s experience of the diagnosis and treatment process. The physician then discusses alpha-1 antitrypsin deficiency diagnosis and management in the context of the patient’s experiences.

Granularity of SERPINA1 alleles by DNA sequencing in CanCOLD

DNA sequencing of the SERPINA1 gene to detect α₁-antitrypsin (AAT) deficiency (AATD) may provide a better appreciation of the individual and cumulative impact of genetic variants on AAT serum levels and COPD phenotypes.AAT serum level and DNA sequencing of the coding regions of SERPINA1 were performed in 1359 participants of the Canadian Cohort Obstructive Lung Disease (CanCOLD) study. Clinical assessment for COPD included questionnaires, pulmonary function testing and computed tomography (CT) imaging. Phenotypes were tested for association with SERPINA1 genotypes collated into four groups: normal (MM), mild (MS and MI), intermediate (heterozygote MZ, non-S/non-Z/non-I, compound IS, and homozygote SS) and severe (ZZ and SZ) deficiency. Smoking strata and MZ-only analyses were also performed.34 genetic variants were identified including 25 missense mutations. Overall, 8.1% of alleles in this Canadian cohort were deficient and 15.5% of 1359 individuals were carriers of at least one deficient allele. Four AATD subjects were identified and had statistically lower diffusion capacity and greater CT-based emphysema. No COPD phenotypes were associated with mild and intermediate AATD in the overall cohort or stratified by smoking status. MZ heterozygotes had similar CT-based emphysema, but lowered diffusion capacity compared with normal and mild deficiency.In this Canadian population-based cohort, comprehensive genetic testing for AATD reveals a variety of deficient alleles affecting 15.5% of subjects. COPD phenotype was demonstrated in severe deficiency and MZ heterozygotes. This study shows the feasibility of implementing a diagnostic test for AATD using DNA sequencing in a large cohort.

Heterozygous Genotype rs17580 AT (PiS) in SERPINA1 is Associated with COPD Secondary to Biomass-Burning and Tobacco Smoking: A Case-Control and Populational Study

Purpose

The protease inhibitor S (PiS) and Z (PiZ) variants have been stated as the only genetic cause of chronic obstructive pulmonary disease (COPD) in Caucasians. However, its frequency in admixed populations is low. We aimed to identify genetic susceptibility between PiS (rs17580) and PiZ (rs28929474) polymorphisms with COPD related to tobacco smoking and biomass-burning smoke as well as to determine its frequencies in Mestizo and Amerindian populations from Mexico.

Patients and Methods

One thousand and eight hundred seventy-eight subjects were included in two comparisons of cases and controls, (1) smokers with and without COPD (COPD-S, n=399; SWOC, n=1106); (2) Biomass-burning smoke-exposed subjects with and without COPD (COPD-BS, n=98; BBES, n=275). In addition, 2354 Mexican subjects identified as Mestizos (n=1952) and Amerindian (n=402) were included. The population structure was evaluated using 59 informative ancestry markers.

Results

The AT genotype of rs17580 is associated with COPD in both comparisons (COPD-S vs SWOC p<0.001, OR=2.16; COPD-BS vs BBES p<0.0001, OR=11.50). The population of the Mexico-North has a greater Caucasian contribution (54.7%) compared to the center (46.9%) and southeast (42.7%).

Conclusion

The rs17580, AT genotype, is associated with COPD in Mexican-Mestizo smokers and exposed to biomass-burning smoke. The rs17580 AT is more frequent in the Mexican-Mestizo population of the North of the country, which has a high Caucasian component.

α-1 Antitrypsin Genotype-Phenotype Discrepancy in a 42-Year-Old Man Who Carries the Null-Allele

BACKGROUND

Alpha-1-antitrypsin (A1AT) deficiency is a hereditary condition caused by mutations in the SERPINA1 gene and associated with lung emphysema and liver disease. Laboratory testing in suspected A1AT deficiency involves quantifying serum A1AT concentration and identification of specific alleles by genotyping and phenotyping. The aim of this report was to present a case of the null allele carrier with consequent genotype/phenotype/concentration discrepancies and potential misclassification of the Z variant in a 42-year-old white man presenting with symptoms of chronic obstructive pulmonary disease (COPD).

METHOD

Serum A1AT concentration was measured using an immunoturbidimetric assay. A1AT phenotype was determined using isoelectric focusing followed with immunofixation (IEF-IF). Genotyping specifically for the S and Z allele was performed by melting curve analysis using real-time PCR and checked by an alternative PCR-RFLP method. Genotype/phenotype ambiguity and discrepancy were amended using gene sequencing.

RESULTS

Laboratory testing revealed highly reduced A1AT concentration (less than 0.30 g/L), mild to moderate deficient genotype (Pi*Z allele: M/Z and Pi*S allele: M/M) and severe deficient Z homozygous phenotype (Pi ZZ). After repeated sampling, the same discordant results were verified by these tests. Further sequencing revealed two clinically relevant and defective variants: rs199422210 (a rare null allele) and rs28929474 (the Z allele).

CONCLUSION

Due to inability of genotyping kit probes to detect null/Z allele combination (which mimics the Pi ZZ phenotype), our patient was misclassified as mild to moderate deficient Pi*MZ heterozygote. In all unclear cases, whole-gene sequencing is highly recommended in order to determine definitive cause of A1AT deficiency.

Electrophoretic α1-globulin for screening of α1-antitrypsin deficient variants

Background

Available screening procedures for the detection of α1-antitrypsin-deficient (AATD) mutations have suboptimal cost-effectiveness ratios. The aim in this study was to evaluate and compare the viability of a composite approach, primarily based on the α1-globulin fraction, in identifying AAT genetic analysis eligible patients against standard screening procedures, based on clinically compatible profiling and circulating AAT < 1 g/L.

Methods

A total of 21,094 subjects were screened for AATD and deemed eligible when meeting one of these criteria: α1-globulin ≤2.6%; α1-globulin 2.6%–2.9% and AST: >37 U/L and ALT: > 78 U/L; α1-globulin %: 2.9–4.6% and AST: >37 U/L and ALT: >78 U/L and erythrocyte sedimentation rate (ESR) >34 mm/h and C-reactive protein (CRP) >3 mg/L. Subjects were genotyped for the AAT gene mutation. Detection rates, including those of the rarest variants, were compared with results from standard clinical screenings. Siblings of mutated subjects were included in the study, and their results compared.

Results

Eighty-two subjects were identified. Among these, 51.2% were found to carry some Pi*M variant versus 15.9% who were clinically screened. The detection rates of the screening, including relatives, were: 50.5% for the proposed algorithm and 18.9% for the clinically-based screening. Pi*M variant prevalence in the screened population was in line with previous studies. Interestingly, 46% of subjects with Pi*M variants had an AAT plasma level above the 1 g/L threshold.

Conclusions

A composite algorithm primarily based on the α1-globulin fraction could effectively identify carriers of Pi*M gene mutation. This approach, not requiring clinical evaluation or AAT serum determination, seems suitable for clinical and epidemiological purposes.

Alpha-1 Antitrypsin Deficiency and Pregnancy

Alpha-1 Antitrypsin Deficiency (A1AD) is a hereditary condition characterized by low levels of circulating alpha-antitrypsin (AAT) in plasma. It is the best understood genetic risk factor for the development of chronic obstructive pulmonary disease (COPD). The diagnosis of A1AD is under-recognized. While there is a significant heterogeneity in disease presentation in relation to the severity of symptoms and prognosis, it is not uncommon for young individuals, including pregnant women to already have moderate to advanced lung disease at the time of diagnosis. Reductions in AAT levels may have unique implications for a gravid patient beyond that of lung disease. Care of the pregnant A1AD patient with chronic lung disease follows the principles of care for the management of airways disease in general with control of symptoms and reduction in exacerbation risk the main tenets of treatment. The effect of A1AD and augmentation in pregnancy has not been studied and thus care is reliant on expert opinion and clinical experience. Providers caring for pregnant patients with A1AD should consider referral to health care systems and providers with specific expertise in A1AD. Ultimately the decision is left to the individual patient and their physician to weigh the risk benefit of cessation or continuation of therapies. In this review, we present the perinatal course of a woman with A1AD and review the available literature pertaining to AAT and pregnancy and discuss the clinical implications.

Knowledge of Rare Respiratory Diseases among Paediatricians and Medical School Students

Alpha-1-antitrypsin deficiency (AATD) and primary ciliary dyskinesia (PCD) are underdiagnosed rare diseases showing a median diagnostic delay of five to ten years, which has negative effects on patient prognosis. Lack of awareness and education among healthcare professionals involved in the management of these patients have been suggested as possible causes. Our aim was to assess knowledge of these diseases among paediatricians and medical school students to determine which knowledge areas are most deficient. A survey was designed with questions testing fundamental aspects of the diagnosis and treatment of AATD and PCD. A score equal to or greater than 50% of the maximum score was set as the level necessary to ensure a good knowledge of both diseases. Our results indicate a profound lack of knowledge of rare respiratory diseases among paediatric professionals and medical students, suggesting that it is necessary to increase rare respiratory diseases training among all physicians responsible for suspecting and diagnosing them; this will allow early diagnosis and the setup of preventive measures and appropriate early-stage treatment. The first step in closing this knowledge gap could be to include relevant material in the medical syllabus.