AAT Genotypes Research Articles

Prevalence of Alpha-1 Antitrypsin Deficiency Alleles in a Lithuanian Cohort of Wheezing Small Children.

Severe inherited alpha-1 antitrypsin deficiency (AATD) is an autosomal genetic condition linked to chronic obstructive pulmonary disease (COPD). The significance of heterozygous, milder deficiency variants (PiSZ, PiMZ, PiMS) is less clear. We studied AATD genotypes in 145 children (up to 72 months old) with assessed wheezing severity using the Pediatric Respiratory Assessment Measure (BCCH PRAM score). A control group of 74 children without airway obstruction was included. AAT concentration and Pi phenotype were determined from dry blood spot samples using nephelometry and real-time PCR; PiS and PiZ alleles were identified by isoelectrofocusing. Among the wheezers, the Pi*S allele incidence was 2.07% (3 cases) and the Pi*Z allele was 6.9% (10 cases). The Pi*Z allele frequency was higher in wheezers compared to controls (44.8% vs. 20.27%) and the general Lithuanian population (44.8% vs. 13.6%) and was similar to adult COPD patients in Lithuania: Pi*S 10.3% vs. 15.8% and Pi*Z 44.8% vs. 46.1%. No association was found between AAT genotypes and wheezing severity. Finding that wheezer children exhibit a frequency of Z* and S* alleles like that found in adults with COPD suggests a potential genetic predisposition that links early wheezing in children to the development of COPD in adulthood. Larger cohort studies are needed to confirm this finding.

Pathogenic Mutations Conferring α1-Antitrypsin Deficiency Are Identified Accurately by a Novel Multiplexed Molecular Assay

BackgroundAlpha-1 antitrypsin deficiency (AATD) is a common, under-diagnosed disease caused by mutations in the polymorphic SERPINA1 gene. AATD is often causes chronic obstructive pulmonary disease (COPD), other respiratory ailments and/or severe liver disease. AATD under-diagnosis is associated with the lack of a quick, high precision test for SERPINA1 variants. Research QuestionCan a rapid and more accurate molecular diagnostic assay be developed that identifies AATD disease-associated mutations and outperforms current limited methodology? Study Design and MethodsWe developed a multiplexed PCR assay that that uses mass spectrometry to detect 20 pathogenic SERPINA1 mutations, two normal M allele variants and an additional variant of unknown significance, as an accessible frontline genetic test for AATD. Blood samples from 177 patients with AATD indication, 176 presumed normal genotype patients and 10 buccal swabs or blood spots were tested to validate the assay. Additionally, 760 whole blood samples from AATD indication patients were evaluated to identify AATD-associated mutations. ResultsThe novel genotyping assay described here accurately detected 23 SERPINA1 single nucleotide polymorphisms (SNPs) (“AAT SNP23”). Of 177 AATD samples, 96% had abnormal SNPs, whereas 9.1% of the 176 presumed normal samples had abnormal SNPs. AAT SNP23 genotypes correlated well with known serum AAT levels. This genotyping assay was more accurate and streamlined than phenotyping isoelectric focusing assay used to identify AATD variants. For clinical testing, serum AAT protein level determination and AAT SNP23 genotyping assay were performed. AAT SNP23 was successfully implemented using AATD indication patient samples to evaluate the most common SERPINA1 mutations indicative of AATD. AAT SNP23 has allowed for quick and accurate AAT genotyping of patients. InterpretationWe developed a novel, multiplexed genotyping assay that rapidly and accurately identifies multiple AATD-associated SERPINA1 SNPs. This assay is useful to quickly diagnose AATD in patients with pulmonary and/or hepatic diseases of unknown etiology.

Opinions and Attitudes of Pulmonologists About Augmentation Therapy in Patients with Alpha-1 Antitrypsin Deficiency. A Survey of the EARCO Group

BackgroundAugmentation therapy (AT) is the only specific treatment licensed for patients with alpha-1 antitrypsin deficiency (AATD) associated lung disease. Since patients with severe AATD may have a very different prognosis and AT requires intravenous infusions for life, the decision to initiate AT may be challenging.MethodsThis survey was conducted on 63 experts in AATD from 13 European countries about their opinions and attitudes regarding AT. Participants were asked to rank the importance of 11 identified factors related with the prescription of AT. In addition, each participant was asked to respond to the indication of AT for 30 out of 500 hypothetical cases developed with the combinations of the 11 factors. Each case was evaluated by 3 experts to check the concordance.ResultsThe variables that scored higher on preferences for initiating AT were AAT genotype (score 8.6 from a Likert scale 0–10 (SD: 1.7)), AATD serum level (8.2 (SD:2.4)) and FEV1 (%) decline (7.9 (SD:2.4)). Among the 500 different cases, there was an agreement in indication of AT among the 3 experts in 291 (58.2%). Regarding the variables associated with AT, it was indicated to 81.9% of Pi*ZZ, 52.4% of Pi*SZ and 9.8% of Pi*MZ (p < 0.0001). For Pi*ZZ patients, multivariate analysis identified younger age, reduced FEV1 (%), higher FEV1 decline and worse emphysema as significantly associated with prescription (AUC = 0.8114); for Pi*SZ variables were younger age, worse FEV1 (%) and worse emphysema (AUC = 0.7414); and for Pi*MZ younger age, worse DLCO (%), higher DLCO decline and dyspnea (AUC = 0.8387).ConclusionThere is a high variability in the criteria for prescription of AT among European experts. Most cases were recommended AT according to guidelines, but a significant number of patients with genotype Pi*SZ and almost 10% Pi*MZ were recommended to initiate AT despite the lack of evidence of efficacy in these genotypes.

A Novel Detection Method to Identify Individuals with Alpha-1 Antitrypsin Deficiency: Linking Prescription of COPD Medications with the Patient-Facing Electronic Medical Record.

Alpha-1 antitrypsin deficiency (AATD) is under-recognized, prompting the need for enhanced detection strategies. The primary aim of this study is to determine the feasibility of using the electronic medical record (EMR) and linked electronic patient messages (EPM) to encourage AATD testing by patients with chronic obstructive pulmonary disease (COPD). Study participants were eligible, untested adult patients who were prescribed an inhaled medication which is exclusively Food and Drug Administration-approved for treating COPD. Eligible patients received a message with basic information about AATD and availability of free, home-based AATD testing. Through a collaboration with the Alpha-1 Foundation's Alpha-1 Coded Testing (ACT) study, patients referred to home-based testing through EPM were flagged. The effectiveness of the electronic message was evaluated by the proportion of patients who underwent testing, and the rate of detecting individuals with severe deficiency of AAT among those tested. A total of 12,369 patients on eligible inhalers were screened; 5430 patients met all criteria and received an EPM. During the study, 396 patients (7.3%) fully requested an ACT kit. Of these, 209 patients (52.8%) returned the test sample and received genotyping results; 65.5%, had a normal AAT genotype (PI*MM), 31.6% were heterozygotes for a deficient allele (PI*MS, PI*MZ and PI*M/Null rare), and 2.9% had severe deficiency of alpha-1 antitrypsin (PI*SZ, PI*ZZ, PI*S/Null rare). While the response rate and test return rate were low, the rate of detecting individuals with AATD using this detection strategy exceeds that of many prior strategies. As such, while requiring independent validation in other populations, this detection strategy holds promise.

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

PurposeAlpha-1-antitrypsin deficiency (AATD) is a rare hereditary condition characterized by low circulating levels of alpha-1antitrypsin (AAT). While the association between AATD and COPD/emphysema is undisputed, the association between AATD and asthma or bronchiectasis is still a matter of debate.Aims and ObjectivesOur study aimed to investigate the distribution of AAT genotypes between patients with COPD/emphysema, asthma and bronchiectasis. To back up the diagnostic labels, we described symptoms associated with the diagnosis.MethodsBetween September 2003 and March 2020, 29,465 testing kits (AlphaKit®) were analyzed in the AAT laboratory, University of Marburg, Germany. The diagnosis of AATD has been made based on the measurements of AAT serum levels, followed by genotyping, phenotyping or whole gene sequencing depending on the availability and/or the need for more detailed interpretation of the results. The respiratory symptoms were recorded as well.ResultsRegarding the distribution of the wild type allele M and the most frequent mutations S (E264V) and Z (E342K), no significant differences could be found between COPD/emphysema [Pi*MM (58.24%); Pi*SZ (2.49%); Pi*ZZ (9.12%)] and bronchiectasis [Pi*MM (59.30%) Pi*SZ (2.81%); Pi*ZZ (7.02%)]. When COPD/emphysema and bronchiectasis were recorded in the same patient, the rate of Pi* ZZ (14.78%) mutations was even higher. Asthma patients exhibited significantly less deficient genotypes [Pi*MM (54.81%); Pi*SZ (2%); Pi*ZZ (2.77%)] than two other groups. Associated respiratory symptoms confirmed the diagnosis.ConclusionCOPD/emphysema and bronchiectasis, but not asthma patients, exhibit higher frequency of AATD genotypes. Our data suggest that AATD testing should be offered to patients with COPD/emphysema and bronchiectasis.

Sex differences in alpha-1-antitrypsin deficiency lung disease-analysis from the German registry

Alpha-1-antitrypsin deficiency (AATD) is a rare condition with clinical mani-festations of the lung and the liver. There is evidence that the gender affects the clinical presentation of non-AATD chronic obstructive lung disease (COPD). The aim of this study was to analyze gender-dependent disease pattern in AATD-based COPD. Data from 1066 individuals from the German AATD registry were analyzed by descriptive and analytical statistics. The AAT genotypes comprised 820 individuals with PiZZ (male 56%, female 45%), 109 with PI SZ (male 55%; female 45%), and others (n = 137). A subgroup of 422 patients with available post-bronchodilator FEV1% predicted was analyzed in detail after stratification in spirometric GOLD stages I-IV. The age of the registered individuals is 52.2 ± 13.4 years (male: 51.91 ± 13.86 years; female: 52.76 ± 13.39 years). Female patients with GOLD I-IV showed lower numbers of pack-years and lower BMI. The time between the first symptom and the establishment of the correct diagnosis was significantly longer in female (14.47 ± 16.46 years) as compared to male individuals (12.39 ± — 14.38 years, p = 0.04). In conclusion, the data of the registry allow to characterize the natural course of the disease and highlight differences in the clinical presentation of patients with AATD-dependent COPD.

α1-Antitripsin deficiency in a pulmonologist' practice

α1 Antitripsin deficiency (AAT) is an orphan respiratory disease. Genetic risk factors of chronic obstructive pulmonary disease (COPD) can cause AAT and primary emphysema of the lungs. AAT genotyping plays the key role for diagnosis. Early detection of AAT deficient phenotypes is crucial for prevention and treatment of COPD and slowing emphysema progression. A case of inherited AAT deficiency in a patient with deficient phenotype PiZZ is described in this article. A diagnostic algorithm for AAT is proposed.

Association between a Genetic Variant of Type-1 Cannabinoid Receptor and Inflammatory Neurodegeneration in Multiple Sclerosis

Genetic ablation of type-1 cannabinoid receptors (CB1Rs) exacerbates the neurodegenerative damage of experimental autoimmune encephalomyelitis, the rodent model of multiple sclerosis (MS). To address the role on CB1Rs in the pathophysiology of human MS, we first investigated the impact of AAT trinucleotide short tandem repeat polymorphism of CNR1 gene on CB1R cell expression, and secondly on the inflammatory neurodegeneration process responsible for irreversible disability in MS patients. We found that MS patients with long AAT repeats within the CNR1 gene (≥12 in both alleles) had more pronounced neuronal degeneration in response to inflammatory white matter damage both in the optic nerve and in the cortex. Optical Coherence Tomography (OCT), in fact, showed more severe alterations of the retinal nerve fiber layer (RNFL) thickness and of the macular volume (MV) after an episode of optic neuritis in MS patients carrying the long AAT genotype of CNR1. MS patients with long AAT repeats also had magnetic resonance imaging (MRI) evidence of increased gray matter damage in response to inflammatory lesions of the white matter, especially in areas with a major role in cognition. In parallel, visual abilities evaluated at the low contrast acuity test, and cognitive performances were negatively influenced by the long AAT CNR1 genotype in our sample of MS patients. Our results demonstrate the biological relevance of the (AAT)n CNR1 repeats in the inflammatory neurodegenerative damage of MS.

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, FEV1/FVC ratio < 0.7, with post-bronchodilator FEV1<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 (FEV1, FVC, FEV1/FVC ratio, TLC, and FEV1/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.

Alpha-1-antitrypsin deficiency

Alpha-1-antitrypsin deficiency (AATD) is a rare genetic disorder associated with the development of liver and lung disease. AAT is a 52-kD glycoprotein, produced mainly by hepatocytes and secreted into the blood. Agglomeration of the AAT-protein in hepatocytes can result in liver disease. Exposure to smoke is the major risk factor for the development of lung disease characterised as early chronic obstructive lung disease (COPD). Diagnosis is based on the analysis of the AAT genotype and phenotype. The measurement of the AAT serum level is useful as screening test. Liver biopsy is not necessary to establish the diagnosis. Therapy for AAT-related liver disease is supportive, a specific therapy is not available. AATD is a rare condition (1:5000-10000) and, as a consequence, data and information on diagnosis and treatment are not easily accessible. This chapter provides a comprehensive overview on AATD, covering basic biology, diagnostic and therapeutic approaches.

Molecular Diagnostics of Alpha-1-Antitrypsine Deficiency in Clinical Practice

The deficiency of serine protease inhibitor, alpha-1-antitrypsin (AATD), is genetically determined defect that increases the risk of lung and liver disease development. The results of recent epidemiological studies indicate the overwhelming majority of individuals with alpha-1-antitrypsin deficiency still remain undiagnosed. The complete laboratory diagnosis of AATD is based on combination of quantitative and qualitative methods. The measurment of plasma/serum AAT concentration is always the initial test performed in the clinically suspected individuals. Nevertheless, only the AAT phenotype or genotype identification allows the full medical verification of the diagnosis. Among the various techniques of either AAT variant phenotyping or genotyping accepted by reference medical centers worldwide, the isoelectric focusing, real-time-PCR and restriction fragment-length polymorphism PCR (RFLP-PCR) are “considered the most effective” performed the most commonly. The AAT diagnostics in Poland still awaits for introduction into clinical routine. The aim of present review is to outline the major methods of AATD diagnosis and discuss with the special issuing of their potential benefits and disadvantages.

Validation of a Rapid, Simple Method to Measure α1-Antitrypsin in Human Dried Blood Spots

Screening for α1-antitrypsin deficiency (AATD) can be performed with dried blood spots (DBS) on filter paper, which allows quantification of AAT by immunonephelometry (1), identification of the AAT phenotype by isoelectric focusing(2)(3), and/or AAT genotyping (4). In most diagnostic flow-charts, important decisions often depend on the AAT concentration determined from DBS; however, current methods are imprecise, and results from DBS are not identical to those obtained using serum samples(4). We wished to develop a method for quantifying AAT in DBS. We collected 75 specimens from healthy blood donors and 74 from patients with suspected AATD. Samples were centrifuged for 8 min at 1620 g , and the serum or plasma, without manifest hemolysis, was separated and stored at −80 °C. Blood was spotted on filter paper with dashed-line 13-mm printed circles (Schleicher & Schuell Grade 903; lot. W-011) and air-dried. Cards stored in plastic bags at room temperature can be kept for at least 1 year. We measured AAT in serum or plasma by nephelometry (Array 360 System) with a polyclonal anti-human AAT goat antibody and calibrator (CAL2, assigned AAT …

α1-antitrypsin gene polymorphisms are not associated with renal arterial fibromuscular dysplasia

We previously showed that fibromuscular dysplasia (FMD) of the renal artery may be familial. Case reports have associated alpha1-antitrypsin deficiency and FMD. The aim of this study was to test the implication of the alpha1-antitrypsin (AAT) gene in a large cohort of patients with renal FMD. A case-control study comparing the genotype frequencies in 161 consecutive patients with angiographically proven renal FMD with those observed in three sets of controls (353 hypertensive patients, 288 normotensive patients, 444 normotensive women) was conducted. High-resolution echotracking of the carotid and radial arteries was performed in a subset of 77 FMD patients. Three functional polymorphisms of the AAT gene (PiM1, PiZ, PiS) were investigated. Clinical (age 44.3 +/- 13.8 years, 85.1% women) and radiological (77.1% of multifocal lesions) characteristics of the FMD population were consistent with those previously published. No differences were found in AAT genotype frequencies in the FMD subjects compared with the 1085 controls. We found no correlation between the AAT genotypes and the clinical and angiographical characteristics of the FMD patients. Echotracking results confirmed our previously published results in FMD patients with a specific pattern and a mean arterial phenotypic score greater than 3. However, no difference in the arterial score was observed across the genotypes. Polymorphisms PiM1, PiZ and PiS of the AAT gene are not associated with renal FMD or infraclinical carotid lesions detected by echotracking methods. As the true prevalence of renal FMD is not precisely known and alpha1-antitrypsin deficiency is not infrequent in the general population, the association of the two may occur by chance.

Microscale variation in Aat (aspartate aminotransferase) is supported by activity differences between upper and lower shore allozymes of Littorina saxatilis

The role of natural selection in maintaining inherited variation in morphological characters is indisputable. In contrast, genetic variation in allozyme loci is mostly assumed neutral or under weak selection, although enzyme functions are critical to central metabolic processes. A locus coding for aspartate aminotransferase (AAT) is polymorphic with two alleles in the rocky shore gastropod Littorina saxatilis. One allele (Aat 120 ) is most frequent (0.8–0.9) in upper shore subpopulations, while the other (Aat 100 ) dominates (0.7–0.8) lower shore subpopulations only meters below. Earlier studies show this variation to be maintained by divergent selection, but the mechanism is unknown. We measured enzyme activities in AAT extracts from individuals of known Aat genotype in populations from two islands and at three different temperatures. In all treatments lower shore homozygotes (Aat 100/100 ) had higher enzyme activity than upper shore homozygotes (Aat 120/120 ), with heterozygotes having intermediate levels of activity. AAT has a central role in anaerobic energy production in marine mollusks during low-tide periods of emergence, and it might appear surprising that upper shore snails, which are most likely to be emerged, have lower enzyme activity. However, upper shore snails are forced to survive long periods of desiccation, and a low metabolic rate will help to conserve limited resources of energy and nutrients and reduce accumulation of waste products.

Emphysema due to α-Antitrypsin Deficiency: Familial Study of the Ybarcelona Variant

A 39-year-old female patient, an ex-smoker with an 8-pack-year smoking history and severe pulmonary emphysema of early onset, received a diagnosis of alpha(1)-antitrypsin (AAT) deficiency and proved to be a carrier of a new deficient variant, YBARCELONA, derived from the normal M1 variant with two substitutions: one in exon III and the other in exon V. AAT genotype of eight members of the same family and study of lung function of the index case and family members at baseline and after 6 years of follow-up were performed. Five subjects were PiYM, with intermediate serum AAT concentrations and normal pulmonary function. No changes were observed over 6 years in pulmonary function of the PiYM patients who were nonsmokers; however, the PiYY index case presented worsening of pulmonary function with FEV(1) of 33%. The heterozygotes PiYM have AAT concentrations similar to the PiMZ and, at 6 years, the nonsmokers presented no worsening in pulmonary function. The risk associated with this variant in its heterozygous form may be similar to that described for PiMZ.

Alpha1-antitrypsin deficiency: incidence and detection program

Most individuals with AAT deficiency have escaped detection by healthcare systems worldwide. The large number of undiagnosed individuals has made it difficult to define the natural history of the clinical disease accurately, and severe ascertainment bias has colored the clinical descriptions of the disease. Most importantly, undetected individuals lose opportunities for important lifestyle changes and preventive therapies. To address this problem, the World Health Organization has recommended that all patients with chronic obstructive lung disease, and all adults and adolescents with asthma, be tested for AAT deficiency. Historically, the AAT Deficiency Detection Center has tested more than 30 000 individuals for the disease, and we have identified more than 1000 cases of AAT deficiency (approximately 30% of the known cases in the United States). Currently, we are implementing methods for determining AAT concentration (level), phenotype, and genotype in specimens of whole blood dried onto filter paper. This full spectrum of robust tests is performed on samples that are easily obtained and shipped to a central laboratory for processing. Wide application of these procedures may help to bring large numbers of presently undiagnosed patients to medical attention.

Genotyping of α-antitrypsin in ten Croatian families

Objectives: The aims of the study were to determine α-antitrypsin (AAT) genotype by a simple DNA-based method and to investigate the association of AAT genotype and serum AAT concentration in a group of ten families. Methods and results: AAT genotype was determined by PCR-RFLP and serum concentration by radial immunodiffusion in samples from each member of ten families (mother, father, and child/children). In the group of parents, five normal genotypes, Pi MM, with a normal serum AAT concentration, and fifteen Pi MZ genotypes, four of them with slightly decreased (43%–66% of the mean) AAT concentration were detected. In the group of children, particular genotypes followed the mode of inheritance. There were eight Pi MZ, three of them with slightly decreased (52%–60% of the mean) AAT concentration, and five Pi ZZ genotypes with considerably decreased (24%–45% of the mean) AAT concentration. Conclusions: PCR-RFLP is the method of choice for AAT genotyping. AAT concentration is not a reliable biochemical marker of AAT deficiency. Determination of AAT genotype in family studies allows the risk of deficient allele inheritance to be followed up and assessed. Early diagnosis of a deficient AAT genotype contributes to the success of currently widely available AAT replacement therapy.