European screening for alpha1-antitrypsin deficiency in subjects with lung disease

Liver Disorders Caused by Inborn Errors of Metabolism

Inborn errors of metabolism (IEMs) are a vast array of inherited/congenital disorders, affecting a wide variety of metabolic pathways and/or biochemical processes inside the cells. Although IEMs are usually rare, they can be represented as serious health problems. During the neonatal period, these inherited defects can give rise to almost all key signs of liver malfunction, including jaundice, coagulopathy, hepato- and splenomegaly, ascites, etc. Since the liver is a vital organ with multiple synthetic, metabolic, and excretory functions, IEM-related hepatic dysfunction could seriously be considered life-threatening. In this context, the identification of those hepatic manifestations and their associated characteristics may promote the differential diagnosis of IEMs immediately after birth, making therapeutic strategies more successful in preventing the occurrence of subsequent events. Among all possible liver defects caused by IEMs, cholestatic jaundice, hepatosplenomegaly, and liver failure have been shown to be manifested more frequently. Therefore, the current study aims to review substantial IEMs that mostly result in the aforementioned hepatic disorders, relying on clinical principles, especially through the first years of life. In this article, a group of uncommon hepatic manifestations linked to IEMs is also discussed in brief.

Population genetic testing and SERPINA1 sequencing identifies unidentified alpha-1 antitrypsin deficiency alleles and gene-environment interaction with hepatitis C infection

Alpha-1 antitrypsin deficiency (AATD), a relatively common autosomal recessive genetic disorder, is underdiagnosed in symptomatic individuals. We sought to compare the risk of liver transplantation associated with hepatitis C infection with AATD heterozygotes and homozygotes and determine if SERPINA1 sequencing would identify undiagnosed AATD. We performed a retrospective cohort study in a deidentified Electronic Health Record (EHR)-linked DNA biobank with 72,027 individuals genotyped for the M, Z, and S alleles in SERPINA1. We investigated liver transplantation frequency by genotype group and compared with hepatitis C infection. We performed SERPINA1 sequencing in carriers of pathogenic AATD alleles who underwent liver transplantation. Liver transplantation was associated with the Z allele (ZZ: odds ratio [OR] = 1.31, p<2e-16; MZ: OR = 1.02, p = 1.2e-13) and with hepatitis C (OR = 1.20, p<2e-16). For liver transplantation, there was a significant interaction between genotype and hepatitis C (ZZ: interaction OR = 1.23, p = 4.7e-4; MZ: interaction OR = 1.11, p = 6.9e-13). Sequencing uncovered a second, rare, pathogenic SERPINA1 variant in six of 133 individuals with liver transplants and without hepatitis C. Liver transplantation was more common in individuals with AATD risk alleles (including heterozygotes), and AATD and hepatitis C demonstrated evidence of a gene-environment interaction in relation to liver transplantation. The current AATD screening strategy may miss diagnoses whereas SERPINA1 sequencing may increase diagnostic yield for AATD, stratify risk for liver disease, and inform clinical management for individuals with AATD risk alleles and liver disease risk factors.

Optimizing the screening of alpha-1 antitrypsin deficiency using serum protein electrophoresis

OBJECTIVES

Alpha-1 antitrypsin (A1AT) deficiency was first identified in patients with emphysema by the absence of the α₁ band on serum protein electrophoresis (SPE). Today, capillary zone electrophoresis is widely performed in laboratories. Here, we compared two SPE systems to detect decreased A1AT concentrations to optimize their use as a screening tool for A1AT deficiency.

METHODS

Serum protein electrophoresis was performed on 200 samples on the Capillarys 2 and the V8 Nexus. The latter presents two α₁ bands (α₁ band 1 and 2) while the Capillarys 2 has only one (Capillarys 2 total α₁). The measures of A1AT and α₁ acid glycoprotein (AAG) were performed as well as the phenotyping of M, S and Z alleles.

RESULTS

At a A1AT cutoff of 0.80 g/L, a cutoff of 1.21 g/L using the V8 Nexus α₁ band 2 corresponded to a 100% sensitivity and a 92.4% specificity while a 1.69% cutoff corresponded to a 100% sensitivity and a 92.4% specificity. The performance of the α₁ band 1 was suboptimal and rather corresponded to AAG. On the Capillarys 2, a cutoff of 2.0 g/L corresponded to a 75.0% sensitivity and a 86.6% specificity, while a 3.2% cutoff showed a 96.4% sensitivity and a 67.4% specificity. The V8 Nexus α₁ band 2 was the method the most correlated with A1AT (r=0.90-0.94).

CONCLUSIONS

The V8 Nexus α₁ band 2 was the best predictor of A1AT deficiency, probably owing to a better resolution. The use of SPE was however unable to predict each phenotype. Phenotype or genotype studies are therefore still advisable in case of A1AT deficiency.

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.

Living with the enemy: from protein-misfolding pathologies we know, to those we want to know

Conformational diseases are caused by the aggregation of misfolded proteins. The risk for such pathologies develops years before clinical symptoms appear, and is higher in people with alpha-1 antitrypsin (AAT) polymorphisms. Thousands of people with alpha-1 antitrypsin deficiency (AATD) are underdiagnosed. Enemy-aggregating proteins may reside in these underdiagnosed AATD patients for many years before a pathology for AATD fully develops. In this perspective review, we hypothesize that the AAT protein could exert a new and previously unconsidered biological effect as an endogenous metal ion chelator that plays a significant role in essential metal ion homeostasis. In this respect, AAT polymorphism may cause an imbalance of metal ions, which could be correlated with the aggregation of amylin, tau, amyloid beta, and alpha synuclein proteins in type 2 diabetes mellitus (T2DM), Alzheimer's and Parkinson's diseases, respectively.

[Alpha-1 antitrypsin deficiency: cause and cofactor for liver disease]

Alpha-1-antitrypsin deficiency (AATD) is a genetic disorder arising due to mutation in alpha1-antitrypsin (AAT). AAT mutations interfere with the AAT production/secretion, cause decreased AAT serum levels and accumulation of AAT in the liver. The excess AAT leads to a proteotoxic liver disease, while the lack of AAT in systemic circulation predisposes to lung injury. While AATD related lung disease is well understood, liver disease needs further awareness. Non-invasive liver stiffness measurement constitutes a useful method to estimate the extent of liver fibrosis. Significant liver fibrosis occurs in 20-35 % of individuals with the classic, severe genotype Pi*ZZ. Genotype Pi*SZ, also known as the compound heterozygous form, confers an increased risk of both liver fibrosis and liver neoplasia. Even the heterozygous genotype Pi*MZ increases the odds of fibrosis in presence of further risk factors such as obesity, male sex, metabolic syndrome and diabetes mellitus. In individuals with non-alcoholic fatty liver disease or alcohol misuse it promotes the development of liver cirrhosis. While no drug treatment exists for AATD-related liver disease, there are several compounds in clinical phase II/III-trials. These either silence the AAT production via siRNA or facilitate the secretion of AAT from the liver due to an improved folding.

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.

[Screening for alpha1-antitrypsin deficiency using dried blood spot: Assessment of the first 20 months]

INTRODUCTION

Alpha1-antitrypsin deficiency is a predisposing factor for pulmonary disease and under-diagnosis is a significant problem. The results of a targeted screening in patients with respiratory symptoms possibly indicative of severe deficiency are reported here.

METHODS

Data were collected from March 2016 to October 2017 on patients who had a capillary blood sample collected during a consultation with a pulmonologist and sent to the laboratory for processing to determine alpha1-antitrypsin concentration, phenotype and possibly genotype.

RESULTS

In 20 months, 3728 test kits were requested by 566 pulmonologists and 718 (19 %) specimens sent: among these, 708 were analyzable and 613 were accompanied by clinical information. Of the 708 samples, 70 % had no phenotype associated with quantitative alpha1- antitrypsin deficiency, 7 % had a phenotype associated with a severe deficiency and 23 % had a phenotype associated with an intermediate deficiency. One hundred and eight patients carried at least one PI*Z allele which is considered to be a risk factor for liver disease.

CONCLUSIONS

The results of this targeted screening program for alpha1- antitrypsin deficiency using a dried capillary blood sample reflect improvement in early diagnosis of this deficiency in lung disease with good adherence of the pulmonologists to this awareness campaign.

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

Pitfalls and caveats in α1-antitrypsin deficiency testing: a guide for clinicians

α1-antitrypsin deficiency (AATD) remains the only readily identified genetic cause of chronic obstructive pulmonary disease (COPD). Furthermore, there is growing evidence that even a moderate deficiency increases the risk of lung disease among smokers. Despite these facts, the uptake of testing for AATD in at-risk populations remains low for many reasons, and a lack of clarity among clinicians regarding the most appropriate diagnostic techniques presents a major deterrent. This Personal View addresses the benefits of diagnosis, the technical basis of the available diagnostic methods, and possible clinical confounders for each test. We include a series of unusual cases encountered at our National Centre of Expertise to provide context. The topics covered should equip clinicians with the core knowledge required to confidently assess patients for AATD.

Diagnosis and management of α1-antitrypsin deficiency in Europe: an expert survey

Despite recent improvements, α1-antitrypsin deficiency (AATD) remains a rarely diagnosed and treated condition. To assess the variability of AATD diagnosis/treatment in Europe, and to evaluate clinicians' views on methods to optimise management, specialist AATD clinicians were invited to complete a web-based survey. Surveys were completed by 15 physicians from 14 centres in 13 European countries. All respondents perceived the AATD diagnosis rate to be low in their country; 77% of physicians believed that ∼15% of cases were diagnosed. Low awareness was perceived as the greatest barrier to diagnosis. Spirometry was considered more practical than quantitative computed tomography (QCT) for monitoring AATD patients in clinical practice; QCT was considered more useful in trials. AAT therapy provision was reported to be highly variable: France and Germany were reported to treat the highest proportion (∼60%) of diagnosed patients, in contrast to the UK and Hungary, where virtually no patients receive AAT therapy. Most clinicians supported self-administration and extended dosing intervals to improve convenience of AAT therapy. This survey indicates that AATD diagnosis and management are highly heterogeneous in Europe; European cooperation is essential to generate data to support access to AAT therapy. Improving convenience of AAT therapy is an ongoing objective.

Alpha-1 antitrypsin deficiency: outstanding questions and future directions

Background

Alpha-1 antitrypsin deficiency (AATD) is a rare hereditary condition that leads to decreased circulating alpha-1 antitrypsin (AAT) levels, significantly increasing the risk of serious lung and/or liver disease in children and adults, in which some aspects remain unresolved.

Methods

In this review, we summarise and update current knowledge on alpha-1 antitrypsin deficiency in order to identify and discuss areas of controversy and formulate questions that need further research.

Results

1) AATD is a highly underdiagnosed condition. Over 120,000 European individuals are estimated to have severe AATD and more than 90% of them are underdiagnosed.

Conclusions

2) Several clinical and etiological aspects of the disease are yet to be resolved. New strategies for early detection and biomarkers for patient outcome prediction are needed to reduce morbidity and mortality in these patients; 3) Augmentation therapy is the only specific approved therapy that has shown clinical efficacy in delaying the progression of emphysema. Regrettably, some countries reject registration and reimbursement for this treatment because of the lack of larger randomised, placebo-controlled trials. 4) Alternative strategies are currently being investigated, including the use of gene therapy or induced pluripotent stem cells, and non-augmentation strategies to prevent AAT polymerisation inside hepatocytes.

A New SERPINA-1 Missense Mutation Associated with Alpha-1 Antitrypsin Deficiency and Bronchiectasis

Alpha-1-antitrypsin deficiency (AATD) is a genetic condition caused by SERPINA1 mutations, which culminates into lower protease inhibitor activity in the serum and predisposes to emphysema. Clinical manifestations of AATD are often associated to ZZ (p.Glu342Lys) and SZ (p.Glu264Val) genotypes and less frequently to rare deficiency or null alleles in heterozygous and homozygous states. We report a case of a 52-year-old woman with bronchiectasis without other potential causes other than an electrophoresis that showed a decrease of alpha-1 globin band and AAT levels below the normal value (78 mg/dl; v.n. 90-200 mg/dl). No S or Z mutation was identified, but sequencing analysis found a novel missense variant Ile74Asn (c.221T > A) in heterozygous state on an M3 allele (Glu400Asp) in the exon 2 of the SERPINA-1gene, probably leading to a dysfunctional protein. This mutation has never been previously identified, and it is interesting to note the association with bronchiectasis in the absence of emphysema.

Alpha-1-antitrypsin deficiency: increasing awareness and improving diagnosis

Alpha-1-antitrypsin deficiency (AATD) is a hereditary disorder that is characterized by a low serum level of alpha-1-antitrypsin (AAT). The loss of anti-inflammatory and antiproteolytic functions, together with pro-inflammatory effects of polymerized AAT contribute to protein degradation and increased inflammation resulting in an increased risk of developing chronic obstructive pulmonary disease (COPD) and emphysema, especially in smokers. AATD is a rare disease that is significantly underdiagnosed. According to recent data that are based on extrapolations, in many countries only 5-15% of homozygous individuals have been identified. Furthermore, the diagnostic delay typically exceeds 5 years, resulting in an average age at diagnosis of about 45 years. Although the American Thoracic Society/European Respiratory Society recommendations state that all symptomatic adults with persistent airway obstruction should be screened, these recommendations are not being followed. Potential reasons for that include missing knowledge about the disease and the appropriate tests, and the low awareness of physicians with regard to the disorder. Once the decision to initiate testing has been made, a screening test (AAT serum level or other) should be performed. Further diagnostic evaluation is based on the following techniques: polymerase chain reaction (PCR) for frequent and clinically important mutations, isoelectric focusing (IEF) with or without immunoblotting, and sequencing of the gene locus coding for AAT. Various diagnostic algorithms have been published for AATD detection (severe deficiency or carrier status). Modern laboratory approaches like the use of serum separator cards, a lateral flow assay to detect the Z-protein, and a broader availability of next-generation sequencing are recent advances, likely to alter existing algorithms.