Detection of alpha-1 antitrypsin deficiency: a review

Alpha-1 antitrypsin deficiency and pregnancy complications and birth outcomes: A population-based cohort study in Denmark

BACKGROUND

Alpha-1 antitrypsin deficiency (AATD) is related to developing lung and liver disease, but no large-scale studies examine its association with birth outcomes.

OBJECTIVE

We investigated the risk of pregnancy complications and adverse birth outcomes in mothers and children with AATD.

METHODS

Using a large cohort data of Danish mothers and children with AATD from 1973 to 2013 (n = 2,027,229), with 559 cases (305 mothers and 254 children). We conducted Poisson regression to examine associations between alpha-1 antitrypsin deficiency, adverse birth outcomes, and pregnancy complications in mothers and children.

RESULTS

AATD was related to term low birth weight [<2500g; Risk Ratio(RR) = 2.04, 95% confidence interval (CI): 1.50-2.79], lowest quartile of abdominal circumference at birth in children of non-smoking mothers (RR = 1.55, 95% CI: 1.14-2.11), delivery via Cesarean-section (RR = 1.59, 95% CI: 1.05-2.40), preterm birth (RR = 1.54, 95% CI: 1.19-2.00) and preeclampsia (RR = 2.64, 95% CI: 1.76-3.94).

CONCLUSIONS

This emphasizes the need for mothers with AATD to be monitored closely during pregnancy to reduce the risk of adverse birth outcomes. Routine screening for alpha-1 antitrypsin in pregnancy may be considered among mothers with a pulmonary and liver disease history.

Measuring of Alpha-1 Antitrypsin Concentration by Nephelometry or Turbidimetry

Most clinical laboratories quantify alpha-1 antitrypsin using either nephelometry or turbidimetry techniques because they are commercially available, amenable to automation, and precise. Both methods are based on light scatter. The foundation of both techniques is based on incubation of the specimen with anti-AAT polyclonal antibody solution, a polymer matrix between endogenous AAT and the reagent antibodies forms, leading to production of light-scattering large particles. Although these two terms are sometimes used synonymously, technically speaking they are not.Nephelometry measures the amount of turbidity or cloudiness of a solution by directly quantifying the intensity of the light scattered by insoluble particles in the sample. Therefore, this technique measures the light that passes through the sample, with the detector being placed at an angle from the sample. Turbidimetry is the process of measuring the loss of intensity of the light transmitted linearly through a sample caused by the scattering effect of insoluble particles. The decrease in light transmission is measured compared to a reference, and the absorbed light is quantified.Beyond specific technical differences between both techniques, there are two major differences between the two procedures that may influence the results. First, the concentration of the sample and the resulting intensity of scattered light relative to the intensity of the light source is one major factor. Second, the size of the scattering particles is also a key differentiating factor. This chapter describes the technical requirements, the different protocols, and the clinical applicability of these two techniques in the diagnosis of alpha-1 antitrypsin deficiency.

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.

Cleaning up alpha-1 antitrypsin deficiency related liver disease

PURPOSE OF REVIEW

Alpha-1 antitrypsin deficiency (AATD) is one of the most common genetic disorders arising due to mutations in alpha-1 antitrypsin (AAT) gene affecting primarily the lung and the liver. This review summarizes the pathophysiology and clinical manifestation of different AATD genotypes and discusses the recent therapeutic developments. The focus is on the severe, rare homozygous Pi∗ZZ and the common heterozygous Pi∗MZ genotype.

RECENT FINDINGS

Pi∗ZZ individuals harbor an up to 20 times higher risk of liver fibrosis and cirrhosis than noncarriers and liver transplantation is currently the only available therapeutic option. AATD constitutes a proteotoxic disorder arising from hepatic AAT accumulation and the currently most promising data come from a phase 2, open-label trial of fazirsiran, a hepatocyte-targeted siRNA. Pi∗MZ subjects display an increased risk of advanced liver disease and at the latter stage, a faster deterioration than individuals without AAT mutation.

SUMMARY

Although the fazirsiran data offer a glimpse of hope to AATD patients, a consensus on appropriate study endpoint, a careful patient selection as well as monitoring of long-term safety will be essential for an approval.

COVID-19's impact on care practice for alpha-1-antitrypsin deficiency patients

BACKGROUND

Patients with alpha-1 antitrypsin deficiency (AATD), commonly categorized as a rare disease, have been affected by the changes in healthcare management brought about by COVID-19. This study's aim was to identify the changes that have taken place in AATD patient care as a result of the COVID-19 pandemic in Spain and to propose experts' recommendations aimed at ensuring humanized and quality care for people with AATD in the post-pandemic situation.

METHODS

A qualitative descriptive case study with a holistic single-case design was conducted, using focus groups with experts in AATD clinical management, including 15 health professionals with ties to the Spanish health system (12 pneumologists and 2 hospital pharmacists from 11 different hospitals in Spain) and 1 patient representative.

RESULTS

COVID-19 has had a major impact on numerous aspects of AATD clinical patient management in Spain, including diagnostic, treatment, and follow-up phases. The experts concluded that there is a need to strengthen coordination between Primary Care and Hospital Care and improve the coordination processes across all the organizations and actors involved in the healthcare system. Regarding telemedicine and telecare, experts have concluded that it is necessary to promote this methodology and to develop protocols and training programs. Experts have recommended developing personalized and precision medicine, and patient participation in decision-making, promoting self-care and patient autonomy to optimize their healthcare and improve their quality of life. The possibility of monitoring and treating AATD patients from home has also been proposed by experts. Another result of the study was the recommendation of the need to ensure that plasma donations are made on a regular basis by a sufficient number of healthy individuals.

CONCLUSION

The study advances knowledge by highlighting the challenges faced by health professionals and changes in AATD patient management in the context of the COVID-19 pandemic. It also proposes experts' recommendations aimed at ensuring humanized and quality care for people with AATD in the post-pandemic situation. This work could serve as a reference study for physicians on their daily clinical practice with AATD patients and may also provide guidance on the changes to be put in place for the post-pandemic situation.

Registry-based cohort study of alpha-1 antitrypsin deficiency prevalence, incidence and mortality in Denmark 2000-2018

OBJECTIVE

To estimate the prevalence of diagnosed alpha-1 antitrypsin deficiency (dAATD) in Denmark as of 31 December 2018, and dAATD incidence and mortality from 1 January 2000 to 31 December 2018.

STUDY DESIGN AND SETTING

We used the Danish National Patient Registry to identify patients with dAATD based on the International Classification of Diseases, 10th Revision (ICD-10) code E88.0A and the Danish Civil Registration System (CRS) for population counts and vital status. We estimated dAATD prevalence, incidence and mortality. We compared mortality among patients with dAATD and an age-matched and sex-matched cohort extracted from the Danish CRS. We conducted a sensitivity analysis to examine whether coding changes during 2000-2018, from a general to a more specific ICD-10 code for AATD, and left truncation affected results appreciably.

RESULTS

The prevalence of dAATD was 12.9 (95% CI 11.9 to 13.8) per 100 000 persons. The age distribution was bimodal, with peaks at ages ≤12 and ≥45 years. The incidence rate per 100 000 person-years was 0.90 (95% CI 0.85 to 0.96), again with a bimodal age distribution. Mortality was higher for patients with dAATD than for the general population (mortality rate ratio (mRR) 4.7, 95% CI 4.1 to 5.3), especially for children (mRR 33.8, 95% CI 6.8 to 167.4). The sensitivity analysis indicated that dAATD prevalence might have been as high as 19.7 per 100 000 persons due to less specific ICD-10 coding for AATD early in the study period or 21.4 per 100 000 persons correcting for left truncation.

CONCLUSION

Diagnosed AATD was associated with increased mortality, especially for children. The finding for children was based on few deaths and had very wide 95% CIs.

Prevalence of Alpha-1 Antitrypsin Deficiency, Self-Reported Behavior Change, and Health Care Engagement Among Direct-to-Consumer Recipients of a Personalized Genetic Risk Report

BACKGROUND

Alpha-1 antitrypsin deficiency (AATD) is an autosomal co-dominant condition that predisposes to emphysema, cirrhosis, panniculitis, and vasculitis. Underrecognition has prompted efforts to enhance early detection and testing of at-risk individuals. Direct-to-consumer (DTC) genetic testing represents an additional method of detection.

RESEARCH QUESTION

The study addressed three questions: (1) Does a DTC testing service identify previously undetected individuals with AATD? (2) What was the interval between initial AATD-related symptoms and initial diagnosis of AATD in such individuals? and (3) What was the behavioral impact of learning about a new diagnosis of AATD through a DTC test?

STUDY DESIGN AND METHODS

In this cross-sectional study, 195,014 individuals responded to a survey within the 23andMe, Inc. research platform.

RESULTS

Among 195,014 study participants, the allele frequency for the PI∗S and PI∗Z AATD variants was 21.6% (6.5% for PI∗Z and 15.1% for PI∗S); 0.63% were PI∗ZZ, half of whom reported having a physician confirm the diagnosis. Approximately 27% of those with physician-diagnosed AATD reported first becoming aware of AATD through the DTC test. Among those newly aware participants, the diagnostic delay interval was 22.3 years. Participants frequently shared their DTC test results with health care providers (HCPs) and the reported impact of learning a diagnosis of AATD was high. For example, 51.1% of PI∗ZZ individuals shared their DTC result with an HCP. The OR for PI∗ZZ smokers to report smoking reduction as a result of receiving the DTC result was 1.7 (95% CI = 1.4-2.2) compared with those without a Z allele and for reduced alcohol consumption this was 4.0 (95% CI = 2.6-5.9).

INTERPRETATION

In this largest available report on DTC testing for AATD, this test, in combination with clinical follow-up, can help to identify previously undiagnosed AATD patients. Moreover, receipt of the DTC AATD report was associated with positive behavior change, especially among those with risk variants.

Alpha-1 antitrypsin deficiency is under-recognized in individuals with cirrhosis undergoing liver transplantation

OBJECTIVE

Under-recognition of alpha-1 antitrypsin deficiency (AATD) is well documented in AATD-lung disease but is rarely reported in patients with liver cirrhosis requiring liver transplantation. This report examines the frequency of newly diagnosed AATD based on pathologic examination of explanted livers following liver transplantation, trends in diagnosis over time, and prognostic correlates of under-recognition outcomes following liver transplantation.

METHODS

This study retrospectively reviewed 1473 pathology reports from adult patients (>18 years) undergoing liver transplantation at Cleveland Clinic between 2004 and 2017. Pathology reports of explanted livers exhibiting periodic acid-Schiff, diastase-resistant inclusion bodies (PAS+G) suggestive of AATD were included and medical records were reviewed regarding demographics, AATD genotype, alternative etiologies for cirrhosis, presence of emphysema, and survival outcomes. Kaplan-Meier estimates of survival outcomes were compared between patients diagnosed pre-liver transplantation and that newly diagnosed post-liver transplantation.

RESULTS

Of 1473 explanted liver pathology reports examined, 117 (7.9%) showed PAS+G suggestive of AATD. The diagnosis of AATD in these 117 patients was established pre-liver transplantation in 36 (30.8%, group 1) and in 46 (39.3%) post-liver transplantation (group 2a). Testing for AATD was not undertaken in 35 (29.9%) of patients despite having PAS+G on explanted livers (group 2b). Post-liver transplantation survival analysis showed a trend (P = 0.098) towards enhanced survival in group 1 vs. group 2 at 10 years.

CONCLUSIONS

This study shows that diagnosis of AATD is overlooked and frequently delayed in patients with cirrhosis undergoing liver transplantation. The observed trend towards higher survival in patients diagnosed with AATD pre-liver transplantation suggests the opportunity to enhance outcomes by earlier recognition of AATD.

Heterozygous Alpha-1 Antitrypsin Deficiency Causing Pulmonary Emboli and Pulmonary Bullae

Alpha-1 antitrypsin deficiency is an autosomal co-dominant disease known for different genetic alterations in the serine protease inhibitor enzyme by which different disease phenotypes can manifest. The lung and the liver are the most common organs involved. The severity of the disease depends on the phenotypes involved. However, emerging evidence shows that this disease can impact multiple organ systems and may even develop regardless of the phenotype. We describe a case of a young man with a known history of the MS phenotype who presented with chest pain and was found to have pulmonary emboli and bullae. His past medical history was relevant for a gastric ulcer and elevated liver enzymes. Due to this young man's age and lack of risk factors for the aforementioned diseases, we propose that these findings were manifestations of his MS phenotype. This case raises multiple questions challenging the presumed benign nature of the MS phenotype. We propose a closer follow-up and lower threshold for diagnostic studies in patients with the heterozygous form.

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.

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.

The Genetics of Pneumothorax

A genetic influence on spontaneous pneumothoraces-those occurring without a traumatic or iatrogenic cause-is supported by several lines of evidence: 1) pneumothorax can cluster in families (i.e., familial spontaneous pneumothorax), 2) mutations in the FLCN gene have been found in both familial and sporadic cases, and 3) pneumothorax is a known complication of several genetic syndromes. Herein, we review known genetic contributions to both sporadic and familial pneumothorax. We summarize the pneumothorax-associated genetic syndromes, including Birt-Hogg-Dubé syndrome, Marfan syndrome, vascular (type IV) Ehlers-Danlos syndrome, alpha-1 antitrypsin deficiency, tuberous sclerosis complex/lymphangioleiomyomatosis, Loeys-Dietz syndrome, cystic fibrosis, homocystinuria, and cutis laxa, among others. At times, pneumothorax is their herald manifestation. These syndromes have serious potential extrapulmonary complications (e.g., malignant renal tumors in Birt-Hogg-Dubé syndrome), and surveillance and/or treatment is available for most disorders; thus, establishing a diagnosis is critical. To facilitate this, we provide an algorithm to guide the clinician in discerning which cases of spontaneous pneumothorax may have a genetic or familial contribution, which cases warrant genetic testing, and which cases should prompt an evaluation by a geneticist.

Alpha1-Antitrypsin Deficiency: Transition of Care for the Child With AAT Deficiency into Adulthood

IMPORTANCE

Alpha1-antitrypsin (AAT) deficiency is a common, but an underdiagnosed genetic condition, affecting 1 in 1500 individuals. It can present insidiously with liver disease in children. Although clinical practice guidelines exist for the management of AAT deficiency, especially with regards to pulmonary involvement, there are no published recommendations that specifically relate to the management of the liver disease and monitoring for lung disease associated with this condition, particularly in children.

OBJECTIVE

To review the literature on the management of AAT deficiency-associated liver disease in adults and children.

EVIDENCE REVIEW

A systematic search for articles indexed in PubMed and published was undertaken. Some earlier selected landmark references were included in the review. Search terms included: "alpha1-antitrypsin deficiency"; "liver disease"; "end-stage liver disease"; "liver transplantation" and "preventative management". Recommendations for the management of children with suspected or confirmed AAT deficiency were made according to the Strength of Recommendation Taxonomy scale.

FINDINGS

Liver complications arising from AAT deficiency result from the accumulation of mutated AAT protein within hepatocytes. Liver disease occurs in 10% of children, manifested by cholestasis, pruritus, poor feeding, hepatomegaly, and splenomegaly, but the presentation is highly variable. A diagnostic test for AAT deficiency is recommended for these children. Baseline liver function tests should be obtained to assess for liver involvement; however, the only curative treatment for AAT deficiency-associated liver disease is organ transplantation. Conclusion and Relevance: There should be a greater vigilance for AAT deficiency testing among pediatricians. Diagnosis should prompt assessment of liver involvement. Children with AATdeficiency- associated liver disease should be referred to a liver specialist and monitored throughout their lifetimes for the symptoms of AAT-deficiency-related pulmonary involvement.

A Novel Approach to Screening for Alpha-1 Antitrypsin Deficiency: Inpatient Testing at a Teaching Institution

Chronic obstructive pulmonary disease (COPD) currently affects more than 16 million Americans and it is estimated that roughly 100,000 Americans have undiagnosed, severe alpha-1 antitrypsin deficiency (AATD) (Chest. 2005;128[3]:1179-1186) (Chest. 2002;122[5]:1818-1829). Patients with AATD have an accelerated rate of decline of lung function caused by proteolytic enzymes. The morbidity associated with this inherited disorder is preventable due to the availability of augmentation therapy. Appropriate inpatient screening of patients with COPD for AATD is lacking and most screening is exclusively limited to outpatient pulmonary clinics. Between May 2016 and February 2017, genetic screening was completed on 54 individuals who were admitted with either a former diagnosis of COPD or active COPD exacerbation to Arnot Ogden Medical Center (AOMC) in Elmira, New York. The incorporation of inpatient genetic screening by resident physicians for AATD in COPD patients led to a high rate of screened and newly diagnosed AATD carriers with a variety of AATD genotypes. It is recommended that there should be an expansion of screening for AATD in hospitalized patients with COPD, regardless of age or smoking history.

Spirituality, Illness Unpredictability, and Math Anxiety Effects on Negative Affect and Affect-Management Coping for Individuals Diagnosed with Alpha-1 Antitrypsin Deficiency

A growing number of genetic tests are included in diagnostic protocols associated with many common conditions. A positive diagnosis associated with the presence of some gene versions in many instances predicts a range of possible outcomes, and the uncertainty linked to such results contributes to the need to understand varied responses and plan strategic communication. Uncertainty in illness theory (UIT; Mishel, 1988, 1990) guided the investigation of efforts to feel in control and hopeful regarding genetic testing and diagnosis for alpha-1 antitrypsin deficiency (AATD). Participants included 137 individuals with AATD recruited from the Alpha-1 Research Registry who were surveyed about their subjective numeracy, anxiety about math, spirituality, perceptions of illness unpredictability, negative affect regarding genetic testing, and coping strategies about a diagnosis. Results revealed that experiencing more fear and worry contributed both directly and indirectly to affect-management coping strategies, operating through individual perceptions of illness unpredictability. The inability to predict the symptoms and course of events related to a genetic illness and anxiety regarding math heightened fear and worry. Spirituality lessened both illness unpredictability and negative affective responses to a diagnosis. Results affirm the importance of clinician and counselor efforts to incorporate attention to patient spirituality. They also illustrate the complexity associated with strategic efforts to plan communication about the different versions of a gene's effects on well-being, when some versions align with mild health effects and others with severe effects.

The prevalence of PI*S and PI*Z SERPINA1 alleles in healthy individuals and COPD patients in Saudi Arabia: A case-control study

Alpha-1 antitrypsin (AAT) is an acute phase protein produced in hepatocytes. Its deficiency affects the lungs and liver. A case-control study was carried out to determine the prevalence of 2 common deficiency alleles, PI*S and PI*Z, for alpha-1 antitrypsin deficiency (AATD) in both healthy and chronic obstructive pulmmonary disease (COPD)-affected Saudi populations and to clarify the importance of genetic tests in the screening of people at risk for COPD.One thousand blood samples from healthy individuals and 1000 from COPD-affected Saudi individuals were genotyped for the above-mentioned alleles, using real-time polymerase chain reaction (PCR), with the exclusion of any other nationalities. Data were analyzed by determining the allele and genotype frequencies through gene counting and its confidence intervals. The allele frequencies, derived by the Hardy-Weinberg equilibrium method, were analyzed by Pearson Chi-squared tests. The confidence intervals for genotype frequencies were calculated using exploratory software for confidence intervals.Of the 1000 COPD patients included in our study, the prevalence of PI*S and PI*Z was 21.8% and 7.7%, respectively, while within the 1000 normal samples, these alleles occurred in 8.9% of patients for PI*S and 1.6% for PI*Z. The AAT deficiency genotype frequencies (PI*ZZ, PI*SS, and PI*SZ) were 6.5 per 1000 and 87 per 1000 for normal and COPD-affected Saudi individuals.Our results indicated a high prevalence of AATD alleles in the normal Saudi population and an association between AAT deficiency and pulmonary disease development. Additionally, our research confirms the importance of genetic screening to achieve early and accurate diagnosis of AATD.

SVIP regulates Z variant alpha-1 antitrypsin retro-translocation by inhibiting ubiquitin ligase gp78

Alpha-1 antitrypsin deficiency (AATD) is an inherited disorder characterized by early-onset emphysema and liver disease. The most common disease-causing mutation is a single amino acid substitution (Glu/Lys) at amino acid 342 of the mature protein, resulting in disruption of the 290–342 salt bridge (an electrophoretic abnormality defining the mutation [Z allele, or ZAAT]), protein misfolding, polymerization, and accumulation in the endoplasmic reticulum of hepatocytes and monocytes. The Z allele causes a toxic gain of function, and the E3 ubiquitin ligase gp78 promotes degradation and increased solubility of endogenous ZAAT. We hypothesized that the accumulation of ZAAT is influenced by modulation of gp78 E3 ligase and SVIP (small VCP-interacting protein) interaction with p97/VCP in ZAAT-expressing hepatocytes. We showed that the SVIP inhibitory effect on ERAD due to overexpression causes the accumulation of ZAAT in a human Z hepatocyte–like cell line (AT01). Overexpression of gp78, as well as SVIP suppression, induces gp78-VCP/p97 interaction in AT01 cells. This interaction leads to retro-translocation of ZAAT and reduction of the SVIP inhibitory role in ERAD. In this context, overexpression of gp78 or SVIP suppression may eliminate the toxic gain of function associated with polymerization of ZAAT, thus providing a potential new therapeutic approach to the treatment of AATD.

Measuring and Interpreting Serum AAT Concentration

Deficiency of alpha-1 antitrypsin (AAT) is caused by mutations in the SERPINA1 gene that results in low concentrations of AAT in circulation. The low AAT concentration can result in uninhibited neutrophil elastase activity in the lung, leading to pulmonary tissue damage and lung disease. Clinical evaluation for possible AAT deficiency includes two critical components: measuring AAT concentration in serum and identification of AAT deficiency alleles. In this chapter the methods by which AAT concentration can be measured in the clinical laboratory are described. The two most common methodologies for AAT quantification employ immunometric techniques, specifically nephelometry and turbidimetry, which are both based on light scatter technology. The AAT in the patient sample is combined with an anti-AAT polyclonal antibody solution leading to polymer formation and a proportional amount of subsequent light scatter. Descriptions of each method are presented, and specifics of quality control and assay parameters are discussed. A special discussion focuses on interpretation of results in the context of the different AAT genetic phenotypes and in the context of patients with active inflammatory conditions. Emerging techniques for AAT quantitation by mass spectrometry are also described given that both AAT quantitation and allele identification can be performed on the same assay.

Results from a large targeted screening program for alpha-1-antitrypsin deficiency: 2003 - 2015

Background

Alpha-1-antitrypsin deficiency (AATD) is an autosomal codominant inherited disease that is significantly underdiagnosed. We have previously shown that the combination of an awareness campaign with the offer of free diagnostic testing results in the detection of a relevant number of severely deficient AATD patients. The present study provides an update on the results of our targeted screening program (German AAT laboratory, University of Marburg) covering a period from August 2003 to May 2015.

Methods

Diagnostic AATD detection test kits were offered free of charge. Dried blood samples were sent to our laboratory and used for the semiquantitative measurement of the AAT-level (nephelometry) and the detection of the S- or Z-allele (PCR). Isoelectric focusing was performed when either of the initial tests was indicative for at least one mutation. Besides, we evaluated the impact of additional screening efforts and the changes of the detection rate over time, and analysed the relevance of clinical parameters in the prediction of severe AATD.

Results

Between 2003 and 2015, 18,638 testing kits were analysed. 6919 (37.12 %) carried at least one mutation. Of those, we identified 1835 patients with severe AATD (9.82 % of the total test population) including 194 individuals with rare genotypes. Test initiatives offered to an unselected population resulted in a dramatically decreased detection rate. Among clinical characteristics, a history of COPD, emphysema, and bronchiectasis were significant predictors for Pi*ZZ, whereas a history of asthma, cough and phlegm were predictors of not carrying the genotype Pi*ZZ.

Conclusion

A targeted screening program, combining measures to increase awareness with cost-free diagnostic testing, resulted in a high rate of AATD detection. The clinical data suggest that testing should be primarily offered to patients with COPD, emphysema, and/or bronchiectasis.

Electronic supplementary material

The online version of this article (doi:10.1186/s13023-016-0453-8) contains supplementary material, which is available to authorized users.

The Diagnosis and Management of Alpha-1 Antitrypsin Deficiency in the Adult

Background: The diagnosis and clinical management of adults with alpha-1 antitrypsin deficiency (AATD) have been the subject of ongoing debate, ever since the publication of the first American Thoracic Society guideline statement in 1989.¹ In 2003, the "American Thoracic Society (ATS)/European Respiratory Society (ERS) Statement: Standards for the Diagnosis and Management of Individuals with Alpha-1 Antitrypsin Deficiency" made a series of evidence-based recommendations, including a strong recommendation for broad-based diagnostic testing of all symptomatic adults with chronic obstructive pulmonary disease (COPD).² Even so, AATD remains widely under-recognized. To update the 2003 systematic review and clinical guidance, the Alpha-1 Foundation sponsored a committee of experts to examine all relevant, recent literature in order to provide concise recommendations for the diagnosis and management of individuals with AATD. Purpose: To provide recommendations for: (1) the performance and interpretation of diagnostic testing for AATD, and (2) the current management of adults with AATD and its associated medical conditions. Methods: A systematic review addressing the most pressing questions asked by clinicians (clinician-centric) was performed to identify citations related to AATD that were published since the 2003 comprehensive review, specifically evaluating publications between January 2002 and December 2014. Important, more recent publications were solicited from the writing committee members as well. The combined comprehensive literature reviews of the 2003 document and this current review comprise the evidence upon which the committee's conclusions and recommendations are based. Results: Recommendations for the diagnosis and management of AATD were formulated by the committee. Conclusions: The major recommendations continue to endorse and reinforce the importance of testing for AATD in all adults with symptomatic fixed airflow obstruction, whether clinically labeled as COPD or asthma. Individuals with unexplained bronchiectasis or liver disease also should be tested. Family testing of first-degree relatives is currently the most efficient detection technique. In general, individuals with AATD and emphysema, bronchiectasis, and/or liver disease should be managed according to usual guidelines for these clinical conditions. In countries where intravenous augmentation therapy with purified pooled human plasma-derived alpha-1 antitrypsin is available, recent evidence now provides strong support for its use in appropriate individuals with lung disease due to AATD.

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.

How Can We Improve the Detection of Alpha1-Antitrypsin Deficiency?

The Z deficiency in α1-antitrypsin (A1ATD) is an under-recognized condition. Alpha1-antitrypsin (A1AT) is the main protein in the α1-globulin fraction of serum protein electrophoresis (SPE); however, evaluation of the α1-globulin protein fraction has received very little attention. Serum Z-type A1AT manifests in polymeric forms, but their interference with quantitative immunoassays has not been reported. Here, 214 894 samples were evaluated by SPE at the G. Fracastoro Hospital of Verona, Italy. Patients with an A1AT level ≤ 0.92 g/L were recalled to complete A1ATD diagnosis. In parallel, to qualitatively and quantitatively characterize A1AT, sera samples from 10 PiZZ and 10 PiMM subjects obtained at the National Institute of Tuberculosis and Lung Diseases in Warsaw, Poland, were subjected to non-denaturing 7.5% PAGE and 7.5% SDS-PAGE followed by Western blot. Moreover, purified A1AT was heated at 60°C and analyzed by a non-denaturing PAGE and 4–15% gradient SDS-PAGE followed by Western blot as well as by isolelectrofocusing and nephelometry. A total of 966 samples manifested percentages ≤ 2.8 or a double band in the alpha1-zone. According to the nephelometry data, 23 samples were classified as severe (A1AT ≤ 0.49 g/L) and 462 as intermediate (A1AT >0.49≤ 1.0 g/L) A1ATD. Twenty subjects agreed to complete the diagnosis and an additional 21 subjects agreed to family screening. We detected 9 cases with severe and 26 with intermediate A1ATD. Parallel experiments revealed that polymerization of M-type A1AT, when measured by nephelometry or isolelectrofocusing, yields inaccurate results, leading to the erroneous impression that it was Z type and not M-type A1AT. We illustrate the need for confirmation of Z A1AT values by “state of the art” method. Clinicians should consider a more in-depth investigation of A1ATD in patients when they exhibit serum polymers and low α1-globulin protein levels by SPE.

Augmentation therapy of alpha-1 antitrypsin deficiency associated emphysema

INTRODUCTION

Alpha-1 antitrypsin, secreted by the liver, inhibits neutrophil elastase. Its deficiency favours the development of emphysema. Restoring a "protective" serum level in deficient patients should make it possible to inhibit the development of emphysema.

STATE OF THE ART

Human plasma-derived alpha-1 antitrypsin is a blood-derived drug sold in France under the name Alfalastin(®). The recommended posology is an I.V. administration of 60 mg/kg once a week. Human plasma-derived alpha-1 antitrypsin restores anti-elastase protection in the lower lung and prevents experimental emphysema induced by the elastasis of human neutrophils in hamster. The low number of patients with alpha-1 antitrypsin deficiency is one of the difficulties to perform sufficiently powerful randomised studies. However, randomised studies have reported the efficacy of human plasma-derived alpha-1 antitrypsin perfusions on mortality, FEV1 decline and the frequency of exacerbations. Randomised control trials have demonstrated the efficacy of human plasma-derived alpha-1 antitrypsin perfusions on the loss of lung density assessed by CT scan.

CONCLUSION

Augmentation therapy is simple in its conception and implementation, but it is expensive. However, there are currently no other solutions.

Indications for active case searches and intravenous alpha-1 antitrypsin treatment for patients with alpha-1 antitrypsin deficiency chronic pulmonary obstructive disease: an update

The effect of hereditary alpha-1 antitrypsin (AAT) deficiency can manifest clinically in the form of chronic obstructive pulmonary disease (COPD). AAT deficiency (AATD) is defined as a serum concentration lower than 35% of the expected mean value or 50 mg/dl (determined by nephelometry). It is associated in over 95% of cases with Pi*ZZ genotypes, and much less frequently with other genotypes resulting from combinations of Z, S, rare and null alleles. A systematic qualitative review was made of 107 articles, focusing mainly on an active search for AATD in COPD patients and intravenous (iv) treatment with AAT. On the basis of this review, the consultant committee of the Spanish Registry of Patients with AATD recommends that all COPD patients be screened for AATD with the determination of AAT serum concentrations, and when these are low, the evaluation must be completed with phenotyping and, on occasions, genotyping. Patients with severe AATD COPD should receive the pharmacological and non-pharmacological treatment recommended in the COPD guidelines. There is enough evidence from large observational studies and randomized placebo-controlled clinical trials to show that the administration of iv AAT reduces mortality and slows the progression of emphysema, hence its indication in selected cases that meet the inclusion criteria stipulated in international guidelines. The administration of periodic infusions of AAT is the only specific treatment for delaying the progression of emphysema associated with AATD.

The challenge of detecting alpha-1 antitrypsin deficiency

Alpha-1 antitrypsin deficiency (AATD) is relatively common but under-recognized. Indeed, fewer than 10% of the estimated 100,000 Americans with AATD have been diagnosed currently, with common reports of long delays between initial symptoms and first detection and the need to see multiple physicians before diagnosis. Because detection can confer benefits (e.g., identification of at-risk family members, lower smoking likelihood, consideration of augmentation therapy), targeted detection of AATD in at-risk groups such as all symptomatic adults with COPD has been endorsed. Two general approaches to detection have been studied: population-based screening (in which testing is performed in a group for whom no increased risk of having AATD exists) and targeted detection or case-finding (in which testing is confined to those with an attributable condition such as COPD or chronic liver disease). Studies to date have suggested that population-based screening is not cost-effective, whereas targeted detection of AATD has been advocated by official society guidelines. Efforts to enhance detection of AATD individuals have included various approaches, including educational campaigns, provision of free test kits, issuance of reminders with medical reports or within an electronic medical record, and empowering respiratory therapists to conduct testing for AATD in pulmonary function laboratories. Such programs have identified individuals with severe deficiency of alpha-1 antitrypsin in up to 12% of subjects, with considerable variation across series by testing criteria. Overall, the persistence of under-recognition of AATD underscores the need for continued efforts to optimize detection of this potentially debilitating genetic disease.

PCR-based screening for the most prevalent alpha 1 antitrypsin deficiency mutations (PI S, Z, and Mmalton) in COPD patients from Eastern Tunisia

It is generally agreed that the protease inhibitor (PI) alleles PI*S (Val264Glu) and PI*Z (Lys342Glu) are the most common alpha 1 antitrypsin deficiency variants worldwide, but the PI*Mmalton allele (ΔPhe52) prevails over these variants in some Mediterranean regions. In eastern Tunisia (Mahdia), we screened 100 subjects with chronic obstructive pulmonary disease for these variants. The PI*S and PI*Z alleles were genotyped by the previously described SexAI/Hpγ99I RFLP-PCR. We provide here a new method for PI*Mmalton genotyping using mismatched RFLP-PCR. These methods are suitable for routine clinical application and can easily be reproduced by several laboratories, since they do not require extensive optimization, unlike the previously described bidirectional allele-specific amplification PCR for PI*Mmalton genotyping. Our results were in agreement with previous reports from central Tunisia (Kairouan), suggesting that the PI*Mmalton mutation is the most frequent alpha 1 antitrypsin deficiency-related mutation in Tunisia.

Expanding the clinical indications for α(1)-antitrypsin therapy

α(1)-Antitrypsin (AAT) is a 52-kDa circulating serine protease inhibitor. Production of AAT by the liver maintains 0.9-1.75 mg/mL circulating levels. During acute-phase responses, circulating AAT levels increase more than fourfold. In individuals with one of several inherited mutations in AAT, low circulating levels increase the risk for lung, liver and pancreatic destructive diseases, particularly emphysema. These individuals are treated with lifelong weekly infusions of human plasma-derived AAT. An increasing amount of evidence appears to suggest that AAT possesses not only the ability to inhibit serine proteases, such as elastase and proteinase-3 (PR-3), but also to exert antiinflammatory and tissue-protective effects independent of protease inhibition. AAT modifies dendritic cell maturation and promotes T regulatory cell differentiation, induces interleukin (IL)-1 receptor antagonist and IL-10 release, protects various cell types from cell death, inhibits caspases-1 and -3 activity and inhibits IL-1 production and activity. Importantly, unlike classic immunosuppressants, AAT allows undeterred isolated T-lymphocyte responses. On the basis of preclinical and clinical studies, AAT therapy for nondeficient individuals may interfere with disease progression in type 1 and type 2 diabetes, acute myocardial infarction, rheumatoid arthritis, inflammatory bowel disease, cystic fibrosis, transplant rejection, graft versus host disease and multiple sclerosis. AAT also appears to be antibacterial and an inhibitor of viral infections, such as influenza and human immunodeficiency virus (HIV), and is currently evaluated in clinical trials for type 1 diabetes, cystic fibrosis and graft versus host disease. Thus, AAT therapy appears to have advanced from replacement therapy, to a safe and potential treatment for a broad spectrum of inflammatory and immune-mediated diseases.

Reference and interpretive ranges for α(1)-antitrypsin quantitation by phenotype in adult and pediatric populations

Laboratory evaluation of α(1)-antitrypsin (A1AT) deficiency involves measurement of circulating A1AT protein (quantitation) and characterization of A1AT genetic polymorphisms (phenotyping or genotyping). This study compared adult and pediatric A1AT reference ranges in patients with nondeficiency alleles and examined A1AT concentrations in multiple other phenotypes. A1AT phenotype and quantitation were retrospectively collected on adult (n = 21,444) and pediatric (n = 2,469) samples that were submitted for laboratory evaluation of A1AT deficiency. The 95% reference ranges for normal adult and pediatric populations with the M/M phenotype were determined to be 100 to 273 mg/dL (18.4-50.2 μmol/L) and 93 to 251 mg/dL (17.1-46.2 μmol/L), respectively (P < .0001). Decreased concentrations of A1AT correlated with heterozygosity and homozygosity for the S and Z alleles in both the adult and pediatric groups. Other rare alleles, such as I, were also associated with decreased concentrations of A1AT, particularly in the context of a Z allele, and may warrant monitoring for symptoms of deficiency.

The prevalence of alpha-1 antitrypsin deficiency among patients found to have airflow obstruction

INTRODUCTION

Alpha-1 antitrypsin deficiency (AATD) is a genetic disease that may be manifested by chronic obstructive pulmonary disease. Despite professional society guidelines that recommend broad testing of at-risk individuals, fewer than 10% of affected individuals have been identified. The goals of this study were to estimate the frequency of abnormal AAT genotypes among patients found to have fixed airflow obstruction and to assess the feasibility of having Pulmonary Function Laboratory personnel administer the study.

METHODS

Nineteen medical centers in the United States participated in the study. Eligible patients (> GOLD II, FEV(1)/FVC ratio < 0.7, with post-bronchodilator FEV(1)<80% predicted) were offered testing for AATD by the Pulmonary Function Laboratory personnel at the time of pulmonary function testing.

RESULTS

A total of 3,457 patients were tested, of whom 3152 were eligible. Deficient patients (ZZ, SZ) constituted 0.63% of subjects, while 10.88% were carriers (MS, MZ). Neither demographic (except African-American race) nor post-bronchodilator pulmonary function variables (FEV(1), FVC, FEV(1)/FVC ratio, TLC, and FEV(1)/FVC) allowed us to predict AAT heterozygote or deficiency status.

CONCLUSIONS

The prevalence of AATD among patients undergoing pulmonary function tests with fixed airflow obstruction was 0.63%. Pulmonary Function Laboratory personnel effectively conducted the study.

A review of α1-antitrypsin deficiency

α(1)-Antitrypsin (AAT) deficiency is an underrecognized genetic condition that affects approximately 1 in 2,000 to 1 in 5,000 individuals and predisposes to liver disease and early-onset emphysema. AAT is mainly produced in the liver and functions to protect the lung against proteolytic damage (e.g., from neutrophil elastase). Among the approximately 120 variant alleles described to date, the Z allele is most commonly responsible for severe deficiency and disease. Z-type AAT molecules polymerize within the hepatocyte, precluding secretion into the blood and causing low serum AAT levels (∼ 3-7 μM with normal serum levels of 20-53 μM). A serum AAT level of 11 μM represents the protective threshold value below which the risk of emphysema is believed to increase. In addition to the usual treatments for emphysema, infusion of purified AAT from pooled human plasma-so-called "augmentation therapy"-represents a specific therapy for AAT deficiency and raises serum levels above the protective threshold. Although definitive evidence from randomized controlled trials of augmentation therapy is lacking and therapy is expensive, the available evidence suggests that this approach is safe and can slow the decline of lung function and emphysema progression. Promising novel therapies are under active investigation.

Population genetic screening for alpha1-antitrypsin deficiency in a high-prevalence area

BACKGROUND

Current guidelines for α1-antitrypsin deficiency (AATD) state that adult population screening should only be done in high-risk areas. Up-to-date genetic methods are always recommended.

OBJECTIVES

To determine the prevalence of AATD in a suspected high-risk area by population screening, applying new genetic analyses and comparing the prevalence of liver and lung abnormalities in subjects with or without AATD.

METHODS

Adult residents of Pezzaze, a village in an Italian alpine valley, voluntarily participated in the screening, and were examined for: nephelometric α1-antitrypsin (AAT) serum level, DNA analysis (mutagenic polymerase chain reaction and restriction fragment length polymorphism tests for Z and S AATD causative mutations, and denaturing high-performance liquid chromatography and/or direct gene sequencing if needed), serum aspartate and alanine transaminases, a respiratory questionnaire and the Medical Research Council dyspnea index scale. The prevalence of AATD was compared with that expected in Italy (Hardy-Weinberg equilibrium), and transaminases and the prevalence of respiratory symptoms were compared between study groups.

RESULTS

Of 1,353 residents, 817 (60.4%) participated; 67 (8.2%) had low AAT serum levels (<90 mg/dl); 118 were carriers of AATD-associated alleles, 4 (0.5%) homozygotes or compound heterozygotes (1 Z, 1 S, 2 ZP(brescia)), 114 (14%) heterozygotes (46 Z, 52 S, 9 P(brescia), 4 M(wurzburg), 2 I, 1 P(lowell)). The prevalence and frequency of all AATD-related alleles was higher than expected for Italy (p < 0.001). There were no differences in symptoms of respiratory disease and transaminases between individuals with normal and low serum AAT.

CONCLUSION

The screening design is one of the main strengths of this study. The large number of mostly asymptomatic individuals with AATD identified suggests that in high-risk areas adult population screening programs employing the latest genetic methods are feasible. Early recognition of individuals at risk means primary or secondary prevention measures can be taken.

The role of augmentation therapy in alpha-1 antitrypsin deficiency

BACKGROUND

Since the recognition of alpha-1 antitrypsin deficiency (A1ATD) in 1963, interest in this condition has increased dramatically. A1ATD is now recognized as the only known genetic condition that leads to emphysema/chronic obstructive pulmonary disease (COPD) in many individuals with the condition. Augmentation therapy with plasma-derived alpha-1 antitrypsin (A1AT) was first introduced in 1987. OBJECTIVES AND SCOPE: To review current evidence on the efficacy, tolerability and biochemical composition of commercially available A1AT augmentation therapies. Literature was sought via electronic searching of bibliographic databases (MEDLINE) and other sources. No language or time period settings were applied. This is a narrative, descriptive review rather than a formal, systematic review.

FINDINGS

Evidence of the therapeutic efficacy of A1AT augmentation therapy is beginning to accumulate, although further randomized, controlled trials are necessary. Clinical studies have reported reduced rates of lung function decline in COPD patients who received augmentation therapy, and significant benefit is seen in patients with forced expiratory volume in 1 second initially in the range of 35-49% of predicted normal. Augmentation therapy has also been shown to decrease the frequency of severe COPD exacerbations and to significantly increase survival rate. Biochemical studies have convincingly demonstrated that weekly intravenous infusion of each of the available plasma-derived A1AT preparations maintains serum A1AT levels above the putative protective threshold. Augmentation therapy with intravenous A1AT is generally well tolerated and long-term therapy in patients with severe A1ATD and pulmonary emphysema is feasible. Differences in the purification processes of available A1AT products are reflected in their relative purities and heterogeneities (abundance of A1AT isoforms), although the commercially available preparations are bioequivalent. Further studies are required to clarify whether variations in biochemical composition of purified A1AT are clinically important.

CONCLUSION

Intravenous augmentation therapy with A1AT currently represents the only viable and specific treatment option for patients with A1ATD.

Alpha-1-antitrypsin deficiency in early childhood

Alpha-1-antitrypsin deficiency (AATD), which predisposes liver disease in children, is often undiagnosed. Isoelectric focusing in 161 infants with liver dysfunction revealed 14.7% severe and 12.2% moderate AATD. Positive PAS-D and immunohistochemical staining was found in 60% of severe AATD, but in moderate AATD, only immunohistochemistry was positive in 100%. Bilirubinostasis, hepatomegaly, splenomegaly, cholestasis, hepatomegaly associated with cholestasis, acholia, high transaminases, and low birthweight were significantly more frequent in severe than in moderate AATD. Both AATDs showed significant portal inflammation, hepatic fibrosis, and viral infection. Early screening in children with liver dysfunction can contribute to the successful detection of AATD.

Impact of a clinical decision support system in an electronic health record to enhance detection of α₁-antitrypsin deficiency

BACKGROUND

Because α(1)-antitrypsin deficiency (AATD) is underrecognized, strategies to enhance guideline-based diagnostic testing are warranted.

METHODS

We studied the impact of issuing a guideline-based alert within an electronic health record (EHR) to test for AATD on the rate of testing for and detection of AATD. For patients at the Cleveland Clinic whose physician-ordered pulmonary function test results showed airflow obstruction, the rates of testing for and detection of AATD were determined during a baseline (prealert) period and again after implementing the alert.

RESULTS

During the baseline period, among 979 eligible subjects, 4.7% were tested; 8.9% of those who had phenotype testing performed were found to have AATD (serum levels < 100 mg/dL), of whom 3.2% had the PI*ZZ genotype. After the alert, among the 624 eligible subjects, the rate of testing increased severalfold (15.1%, P < .001), though neither the rate of detecting AATD (5.3%) nor PI*ZZ (2.6%) differed from the rates during the baseline period. Having an alternate diagnosis (other than asthma) that could explain airflow obstruction (eg, congestive heart failure, sarcoidosis, Langerhans cell histiocytosis) was associated with a lower rate of testing (P = .041), while carrying a diagnosis of asthma tended to increase the testing frequency (P = .15). Multivariate analysis showed that younger age and a smoking history were associated with being tested.

CONCLUSIONS

Issuing an alert within an EHR was associated with a severalfold increase in the frequency of testing for α(1)-antitrypsin without a higher rate of diagnosing severe AATD. While the lack of more frequent diagnosis of AATD may reflect a high rate of baseline detection, these results prompt consideration of additional strategies to enhance detection of AATD.