Molecular diagnosis of alpha1-antitrypsin deficiency: A new method based on Luminex technology

Recent Advances in and Application of Fluorescent Microspheres for Multiple Nucleic Acid Detection

Traditional single nucleic acid assays can only detect one target while multiple nucleic acid assays can detect multiple targets simultaneously, providing comprehensive and accurate information. Fluorescent microspheres in multiplexed nucleic acid detection offer high sensitivity, specificity, multiplexing, flexibility, and scalability advantages, enabling precise, real-time results and supporting clinical diagnosis and research. However, multiplexed assays face challenges like complexity, costs, and sample handling issues. The review explores the recent advancements and applications of fluorescent microspheres in multiple nucleic acid detection. It discusses the versatility of fluorescent microspheres in various fields, such as disease diagnosis, drug screening, and personalized medicine. The review highlights the possibility of adjusting the performance of fluorescent microspheres by modifying concentrations and carrier forms, allowing for tailored applications. It emphasizes the potential of fluorescent microsphere technology in revolutionizing nucleic acid detection and advancing health, disease treatment, and medical research.

Rare variants in alpha 1 antitrypsin deficiency: a systematic literature review

BACKGROUND

Alpha 1 Antitrypsin Deficiency (AATD) is a largely underrecognized genetic condition characterized by low Alpha 1 Antitrypsin (AAT) serum levels, resulting from variations in SERPINA1. Many individuals affected by AATD are thought to be undiagnosed, leading to poor patient outcomes. The Z (c.1096G > A; p.Glu366Lys) and S (c.863A > T; p.Glu288Val) deficiency variants are the most frequently found variants in AATD, with the Z variant present in most individuals diagnosed with AATD. However, there are many other less frequent variants known to contribute to lung and/or liver disease in AATD. To identify the most common rare variants associated with AATD, we conducted a systematic literature review with the aim of assessing AATD variation patterns across the world.

METHODS

A systematic literature search was performed to identify published studies reporting AATD/SERPINA1 variants. Study eligibility was assessed for the potential to contain relevant information, with quality assessment and data extraction performed on studies meeting all eligibility criteria. AATD variants were grouped by variant type and linked to the geographical region identified from the reporting article.

RESULTS

Of the 4945 articles identified by the search string, 864 contained useful information for this study. Most articles came from the United States, followed by the United Kingdom, Germany, Spain, and Italy. Collectively, the articles identified a total of 7631 rare variants and 216 types of rare variant across 80 counties. The F (c.739C > T; p.Arg247Cys) variant was identified 1,281 times and was the most reported known rare variant worldwide, followed by the I (c.187C > T; p.Arg63Cys) variant. Worldwide, there were 1492 Null/rare variants that were unidentified at the time of source article publication and 75 rare novel variants reported only once.

CONCLUSION

AATD goes far beyond the Z and S variants, suggesting there may be widespread underdiagnosis of patients with the condition. Each geographical region has its own distinctive variety of AATD variants and, therefore, comprehensive testing is needed to fully understand the true number and type of variants that exist. Comprehensive testing is also needed to ensure accurate diagnosis, optimize treatment strategies, and improve outcomes for patients with AATD.

Alpha1-antitrypsin deficiency in Greece: Focus on rare variants

PURPOSE

A1Antitrypsin deficiency (AATD) pathogenic mutations are expanding beyond the PI*Z and PI*S to a multitude of rare variants.

AIM

to investigate genotype and clinical profile of Greeks with AATD.

METHODS

Symptomatic adult-patients with early-emphysema defined by fixed airway obstruction and computerized-tomography scan and lower than normal serum AAT levels were enrolled from reference centers all over Greece. Samples were analyzed in the AAT Laboratory, University of Marburg-Germany.

RESULTS

Included are 45 adults, 38 homozygous or compound heterozygous for pathogenic variants and 7 heterozygous. Homozygous were 57.9% male, 65.8% ever-smokers, median (IQR) age 49.0(42.5-58.5) years, AAT-levels 0.20(0.08-0.26) g/L, FEV1(%predicted) 41.5(28.8-64.5). PI*Z, PI*Q0, and rare deficient allele's frequency was 51.3%, 32.9%,15.8%, respectively. PI*ZZ genotype was 36.8%, PI*Q0Q0 21.1%, PI*MdeficientMdeficient 7.9%, PI*ZQ0 18.4%, PI*Q0Mdeficient 5.3% and PI*Zrare-deficient 10.5%. Genotyping by Luminex detected: p.(Pro393Leu) associated with MHeerlen (M1Ala/M1Val); p.(Leu65Pro) with MProcida; p.(Lys241Ter) with Q0Bellingham; p.(Leu377Phefs*24) with Q0Mattawa (M1Val) and Q0Ourem (M3); p.(Phe76del) with MMalton (M2), MPalermo (M1Val), MNichinan (V) and Q0LaPalma (S); p.(Asp280Val) with PLowell (M1Val); PDuarte (M4), YBarcelona (p.Pro39His). Gene-sequencing (46.7%) detected Q0GraniteFalls, Q0Saint-Etienne, Q0Amersfoort(M1Ala), MWürzburg, NHartfordcity and one novel-variant (c.1A>G) named Q0Attikon.Heterozygous included PI*MQ0Amersfoort(M1Ala), PI*MMProcida, PI*Mp.(Asp280Val), PI*MOFeyzin. AAT-levels were significantly different between genotypes (p = 0.002).

CONCLUSION

Genotyping AATD in Greece, a multiplicity of rare variants and a diversity of rare combinations, including unique ones were observed in two thirds of patients, expanding knowledge regarding European geographical trend in rare variants. Gene sequencing was necessary for genetic diagnosis. In the future the detection of rare genotypes may add to personalize preventive and therapeutic measures.

Comprehensive Clinical Diagnostic Pipelines Reveal New Variants in Alpha-1 Antitrypsin Deficiency

Alpha-1 antitrypsin deficiency (AATD) is an underdiagnosed disorder associated with mutations in the SERPINA1 gene encoding alpha-1 antitrypsin (AAT). Severe AATD can manifest as pulmonary emphysema and progressive liver disease. Besides the most common pathogenic variants S (E264V) and Z (E342K), many rarer genetic variants of AAT have been found in patients and in the general population. Here we report a panel of new SERPINA1 variants, including 4 null and 16 missense alleles, identified among a cohort of individuals with suspected AATD whose phenotypic follow-up showed inconclusive or atypical results. Because the pathogenic significance of the missense variants was unclear purely on the basis of clinical data, the integration of computational, biochemical, and cellular studies was used to define the associated risk of disease. Established pathogenicity predictors and structural analysis identified a panel of candidate damaging mutations that were characterized by expression in mammalian cell models. Polymer formation, intracellular accumulation, and secretory efficiency were evaluated experimentally. Our results identified two AAT mutants with a Z-like polymerogenic severe deficiency profile (Smilano and Mcampolongo) and three milder variants (Xsarezzo, Pdublin, and Ctiberias). Overall, the experimentally determined behavior of the variants was in agreement with the pathogenicity scores of the REVEL (an ensemble method for predicting the pathogenicity of rare missense variants) predictor, supporting the utility of this bioinformatic tool in the initial assessment of newly identified amino acid substitutions of AAT. Our study, in addition to describing 20 new SERPINA1 variants, provides a model for a multidisciplinary approach to classification of rare AAT variants and their clinical impact on individuals with rare AATD genotypes.

Alpha1-antitrypsin deficiency: An updated review

Alpha1-antitrypsin deficiency (AATD) is a rare autosomal recessive disease associated with the homozygous Z variant of the SERPINA1 gene. Clinical expression of AATD, reported 60 years ago associate a severe deficiency, pulmonary emphysema and/or liver fibrosis. Pulmonary emphysema is due to the severe alpha1-antitrypsin deficiency of the ZZ homozygous status and is favored by smoking. Liver fibrosis is due to the ZZ homozygous status and is favored by obesity and excessive chronic alcohol intake, with a risk of liver cancer. Diagnosis is based on serum level and either isoelectric focusing determination of the biochemical phenotype or PCR detection of some variants. SERPINA1 gene sequencing is necessary in case of discrepancies between the results of these tests. No treatment is available for the liver disease in AATD. Although no specific trial has been performed, COPD in AATD should be treated as per COPD recommendations. Based on a randomized clinical trial, augmentation therapy is indicated in non-smoking adults less than 70 years of age with emphysema at chest CT, confirmed homozygous AATD, and FEV1 between 35% and 70% of predicted. In contrast Z heterozygosis (MZ or SZ) brings a risk of lung or liver disease only in association with further risk factors. Early detection, in all patients with COPD and chronic liver disease, is critical for the correct information of Z variant carriers. News ways of correcting the liver production of alpha1-antitrypsin will modify the care of AATD patients.

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

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

Distribution of alpha1 antitrypsin rare alleles in six countries: Results from the Progenika diagnostic network

BACKGROUND

Knowledge of the frequency of rare SERPINA1 mutations could help in the management of alpha1 antitrypsin deficiency (AATD). The present study aims to assess the frequencies of rare and null alleles and their respiratory and hepatic pathogenicity.

METHODS

This is a secondary analysis of a study that evaluated the viability of the Progenika diagnostic genotyping system in six different countries by analyzing 30,827 samples from cases of suspected AATD. Allele-specific genotyping was carried out with the Progenika A1AT Genotyping Test which analyses 14 mutations in buccal swabs or dried blood spots samples. SERPINA1 gene sequencing was performed for serum AAT-genotype discrepancies or by request of the clinician. Only cases with rare mutations were included in this analysis.

RESULTS

There were 818 cases (2.6%) carrying a rare allele, excluding newly identified mutations. All were heterozygous except for 20 that were homozygous. The most frequent alleles were the M-like alleles, PI*M_malton and PI*M_heerlen. Of the 14 mutations included in the Progenika panel, there were no cases detected of PI*S_iiyama, PI*Q0_{granite falls} and PI*Q0_west. Other alleles not included in the 14-mutation panel and identified by gene sequencing included PI*M_würzburg, PI*Z_bristol, and PI*Z_wrexham, and the null alleles PI*Q0_porto, PI*Q0_madrid, PI*Q0_brescia, and PI*Q0_kayseri.

CONCLUSIONS

The Progenika diagnostic network has allowed the identification of several rare alleles, some unexpected and not included in the initial diagnostic panel. This establishes a new perspective on the distribution of these alleles in different countries. These findings may help prioritize allele selection for routine testing and highlights the need for further research into their pathogenetic role.

Wilson Disease and Alpha1-Antitrypsin Deficiency: A Review of Non-Invasive Diagnostic Tests

Wilson disease and alpha1-antitrypsin deficiency are two rare genetic diseases that may impact predominantly the liver and/or the brain, and the liver and/or the lung, respectively. The early diagnosis of these diseases is important in order to initiate a specific treatment, when available, ideally before irreversible organ damage, but also to initiate family screening. This review focuses on the non-invasive diagnostic tests available for clinicians in both diseases. These tests are crucial at diagnosis to reduce the potential diagnostic delay and assess organ involvement. They also play a pivotal role during follow-up to monitor disease progression and evaluate treatment efficacy of current or emerging therapies.

Improving the Laboratory Diagnosis of M-like Variants Related to Alpha1-Antitrypsin Deficiency

Alpha1-antitrypsin (AAT) is a serine protease inhibitor that is encoded by the highly polymorphic SERPINA1 gene. Mutations in this gene can lead to AAT deficiency (AATD), which is associated with an increased risk of lung and/or liver disease. On the basis of electrophoretic migration, AAT variants are named with capital letters; M (medium) signifies the normal protein. Among pathological variants, the M-like ones represent a heterogeneous group of rare allelic variants that exhibit the same electrophoretic pattern as the M wild-type protein, which makes them difficult to detect with routine methods. In order to avoid their misdiagnosis, the present study defines and validates effective methods for the detection of two pathogenic M-like variants, M_wurzburg and M_whitstable. Comparison of protein phenotypes using isoelectric focusing of samples that presented the M_wurzburg variant, as revealed by exons 5 sequencing, identified a particular electrophoretic pattern amenable to the M_wurzburg protein. The specific phenotyping pattern was retrospectively validated, thus enabling the detection of 16 patients with M_wurzburg variant among the subjects already tested but not sequenced according to our diagnostic algorithm. The M_whitstable allele was detected by intron 4 sequencing of SERPINA1 gene. M_wurzburg and M_whitstable are often misdiagnosed and the introduction of diagnostic improvements can help the clinical management, especially in patients with established lung disease without any other reported risk factors.

[Alpha 1-antitrypsin deficiency]

INTRODUCTION

Pulmonary emphysema and liver disease are the clinical expressions of alpha 1-antitrypsin deficiency, an autosomal recessive genetic disease.

STATE OF THE ART

Alpha 1-antitrypsin deficiency is usually associated with the homozygous Z variant of the SERPINA1 gene. Its clinical expression always consists in a substantial reduction of alpha 1-antitrypsin serum concentration and its variants are analyzed by isoelectric focalization or molecular techniques. Assessed by CO transfer alteration and CT scan, risk of pulmonary emphysema is increased by tobacco consumption. Assessed by transient elastography and liver ultrasound, risk of liver disease is increased by alcohol consumption or obesity. Treatment of COPD-associated alpha 1-antitrypsin deficiency does not differ from that of other forms of COPD. In patients presenting with severe deficiency, augmentation therapy with plasma-derived alpha 1-antitrypsin reduces the progression of emphysema, as shown in terms of CT-based lung density metrics. Patients with alpha 1-antitrypsin deficiency with a ZZ genotype should refrain from alcohol or tobacco consumption, and watch their weight; so should their close relatives.

PERSPECTIVES

Modulation of alpha 1-antitrypsin liver production offers an interesting new therapeutic perspective.

CONCLUSION

Homozygous (Z) variants of the SERPINA1 gene confer an increased risk of pulmonary emphysema and liver disease, particularly among smokers, drinkers and obese persons.

Feasibility of a genotyping system for the diagnosis of alpha1 antitrypsin deficiency: a multinational cross-sectional analysis

Introduction

Currently, strategies for improving alpha1 antitrypsin deficiency (AATD) diagnosis are needed. Here we report the performance of a multinational multiplex-based genotyping test on dried blood spots and buccal swabs sent by post or courier and with web registration for subjects with suspected AATD in Argentina, Brazil, Chile, Colombia, Spain, and Turkey.

Methods

This was an observational, cross-sectional analysis of samples from patients with suspected AATD from March 2018 to January 2022. Samples were coded on a web platform and sent by post or courier to the central laboratory in Northern Spain. Allele-specific genotyping for the 14 most common mutations was carried out with the A1AT Genotyping Test (Progenika-Grifols, Spain). SERPINA1 gene sequencing was performed if none of the mutations were found or one variant was detected in heterozygous status and the AAT serum level was < 60 mg/dl, or if requested by the clinician in charge.

Results

The study included 30,827 samples: 30,458 (94.7%) with final results after direct genotyping and 369 (1.1%) with additional gene sequencing. Only 0.3% of the samples were not processed due to their poor quality. The prevalence of the most frequent allele combinations was MS 14.7%, MZ 8.6%, SS 1.9%, SZ 1.9%, and ZZ 0.9%. Additionally, 70 cases with new mutations were identified. Family screening was conducted in 2.5% of the samples. Samples from patients with respiratory diseases other than COPD, including poorly controlled asthma or bronchiectasis, also presented AATD mutations.

Conclusions

Our results confirm the viability of this diagnostic system for genotyping AATD conducted simultaneously in different countries. The system has proved satisfactory and can improve the timely diagnosis of AATD.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12931-022-02074-x.

Clinical manifestations of a new alpha‐1 antitrypsin genetic variant: Q0parma

Alpha‐1 antitrypsin deficiency is an autosomal, codominant disorder caused by mutations of the SERPINA1 gene. Several mutations of SERPINA1 have been described associated with the development of pulmonary emphysema and/or chronic liver disease and cirrhosis. Here, we report a very rare PI*Q0parma variant identified for the first time in an Italian family originally from the city of Parma in Northern Italy

An Italian expert consensus on the management of alpha1-antitrypsin deficiency: a comprehensive set of algorithms

BACKGROUND

Alpha1-antitrypin deficiency (AATD) is a genetic-based risk condition, mainly affecting the lungs and liver. Despite its wide distribution, it is largely underdiagnosed, thus being considered a rare disease, and is consequently managed in ad hoc reference centers. Unfortunately, an easy-to-use algorithm for managing such a complex disease is still lacking.

METHODS

An expert consensus meeting was conducted among experts in the management of AATD to build a comprehensive algorithm, including diagnosis, monitoring, AAT therapy, rehabilitation and lung transplantation, and liver disease, that could serve as a guide for physicians and treating centers. A panel of AATD specialists evaluated the results of their work.

RESULTS

Diagnosis is the most delicate phase, and awareness about this condition should be raised among GPs. A set of recommendations has been written about the most suitable follow-up visits. Augmentation therapy with AAT may be useful to reduce the progression of emphysema and lung function decline in selected patients. Exercise capacity may be improved by pulmonary rehabilitation and, in selected cases, by lung volume reduction or lung transplantation. Support therapies are needed for those who develop liver disease, and, in selected cases, liver transplantation may be considered. Patients should be carefully educated about their lifestyle, including smoking cessation, body weight control, and reduced alcohol intake.

CONCLUSIONS

The proposed algorithm obtained the endorsement of the Italian Society of Pneumology (SIP). However, further studies and additional clinical data are required to confirm the validity of these recommendations.

Update on and future perspectives for the diagnosis of alpha-1 antitrypsin deficiency in Brazil

Alpha-1 antitrypsin deficiency (AATD) is a rare genetic disorder caused by a mutation in the SERPINA1 gene, which encodes the protease inhibitor alpha-1 antitrypsin (AAT). Severe AATD predisposes individuals to COPD and liver disease. Early diagnosis is essential for implementing preventive measures and limiting the disease burden. Although national and international guidelines for the diagnosis and management of AATD have been available for 20 years, more than 85% of cases go undiagnosed and therefore untreated. In Brazil, reasons for the underdiagnosis of AATD include a lack of awareness of the condition among physicians, a racially diverse population, serum AAT levels being assessed in a limited number of individuals, and lack of convenient diagnostic tools. The diagnosis of AATD is based on laboratory test results. The standard diagnostic approach involves the assessment of serum AAT levels, followed by phenotyping, genotyping, gene sequencing, or combinations of those, to detect the specific mutation. Over the past 10 years, new techniques have been developed, offering a rapid, minimally invasive, reliable alternative to traditional testing methods. One such test available in Brazil is the A1AT Genotyping Test, which simultaneously analyzes the 14 most prevalent AATD mutations, using DNA extracted from a buccal swab or dried blood spot. Such advances may contribute to overcoming the problem of underdiagnosis in Brazil and elsewhere, as well as being likely to increase the rate detection of AATD and therefore mitigate the harmful effects of delayed diagnosis.

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.

Results of a Diagnostic Procedure Based on Multiplex Technology on Dried Blood Spots and Buccal Swabs for Subjects With Suspected Alpha1 Antitrypsin Deficiency

INTRODUCTION

The objective of this analysis was the evaluation of a new national circuit used for diagnosing alpha1 antitrypsin deficiency (AATD) based on multiplex technology using online registration and mail posted samples from dried blood spots (DBS) and buccal swabs.

METHODS

This is an observational, ongoing study conducted in Spain since March 2018. Samples are coded on a web platform and sent by postal mail to the central laboratory. Allele-specific genotyping for the 14 most common mutations was done with the Luminex 200 Instrument System. Gene sequencing was done if none of the mutations were found and the AAT serum level was <60mg/dl, or by request from the clinician in charge.

RESULTS

At the time of the present report, 5803 (92.9%) samples were processed, 4984 (85.9%) from buccal swab and 819 (14.1%) from DBS. The prevalence of the frequent allele combinations were: MS 19.0%, MZ 14.4%, SS 2.9%, SZ 3.7%, and ZZ: 1.4%. Globally, Z carriers represented 20.0% and S carriers 26.6% of this population, with differences seen between regions. 209 (3.6%) were identified carrying rare alleles, 12 (0.2%) carrying null alleles and 14 (0.3%) new mutations were described. Respiratory diseases other than COPD, including poorly controlled asthma or bronchiectasis, also presented AATD mutations.

CONCLUSIONS

The availability of a diagnostic system based on the simultaneous testing of 14 genetic variants from buccal swabs or DBS sent by postal mail and with web registration has proven to be useful, and the system can improve the timely diagnosis of AATD.

Molecular diagnosis of alpha1-antitrypsin deficiency: A new method based on Luminex technology

Background

Alpha1‐antitrypsin deficiency (AATD) is an under‐diagnosed hereditary disorder characterized by reduced serum levels of alpha1‐antitrypsin (AAT) and increased risk to develop lung and liver diseases at an early age. AAT is encoded by the highly polymorphic SERPINA1 gene. The most common deficiency alleles are S and Z, but more than 150 rare variants lead to low levels of the protein. To identify these pathological allelic variants, sequencing is required. Since traditional sequencing is expensive and time‐consuming, we evaluated the accuracy of A1AT Genotyping Test, a new diagnostic genotyping kit which allows to simultaneously identify and genotype 14 deficiency variants of the SERPINA1 gene based on Luminex technology.

Methods

A total of 418 consecutive samples with AATD suspicion and submitted to the Italian Reference laboratory between January and April 2016 were analyzed both by applying the diagnostic algorithm currently in use, and by applying A1AT Genotyping Test.

Results

The assay gave the following results: 101 samples (24.2%) were positive for at least one of the 14 deficiency variants, 316 (75.6%) were negative for all the variants analyzed. The identified mutations showed a 100% correlation with the results obtained with our diagnostic algorithm. Seventeen samples (4%) resulted negative for the assay but sequencing identified other rare pathological variants in SERPINA1 gene.

Conclusion

The A1AT Genotyping Test assay was highly reliable and robust and allowed shorter diagnostic times. In few cases, it has been necessary to sequence the SERPINA1 gene to identify other rare mutations not included in the kit.