Alpha-1-antitrypsin deficiency: Molecular basis, clinical presentation, therapeutic options and an integrative approach in diagnostics

Primarna uloga alfa-1-antitripsina (AAT) jeste da zaštiti plućni parenhim od proteolize dejstvom neutrofilne elastaze. Njegovu biosintezu kontroliše izuzetno polimorfni GEN SERPINA1. Deficijencija AAT (AATD) jeste autozomalno recesivno oboljenje i smatra se najčešćim genetskim uzrokom oboljenja jetre kod dece i emfizema kod odraslih. Prema učestalosti, deficijentni aleli se mogu podeliti na "česte" (Z i S) i "retke" (Mmalton, Mheerlen, Mprocida itd.). Za vrstu, intenzitet i vremenski period u kome se razvijaju kliničke manifestacije smatra se odgovornim interakcija AATD i dodatnih genetskih i stečenih faktora rizika (pušenje, izloženost aerozagađenju i sl.). Kod obolelih se najčešće javljaju preuranjen emfizem, hronični hepatitis, ciroza i hepatocelularni karcinom. Epidemiološke studije naglašavaju potrebu povećanja dijagnostičke efikasnosti kod AATD. Preporučuje se da dijagnostički pristup integriše precizne, međunarodno identifikovane, kliničke kriterijume i standardizovan laboratorijski protokol, zasnovan na biohemijskim i molekularno-biološkim metodama. Terapijski pristup zavisi od vrste kliničkih manifestacija. Kod pulmoloških bolesnika je moguće primeniti terapiju nadoknade, dok kod osoba sa terminalnom fazom oštećenja jetre uzrokovanog AATD transplantacija trenutno predstavlja jedinu specifičnu terapiju. Kod svih obolelih je neophodno preventivno uticati na smanjenje štetnog uticaja životnih navika i faktora sredine. Očekuje se da zdravstveni ishodi kod obolelih budu značajno unapređeni uvođenjem genske terapije. Dosadašnji rezultati istraživanja efikasnosti integrativnog pristupa detekciji AATD u populaciji Srbije su ohrabrujući i upućuju na potrebu njegovog omasovljenja, čime bi se ostvarili uslovi za formiranje nacionalnog registra obolelih.The primary role of Alpha-1-antitrypsin (AAT), encoded by the highly polymorphic SERPINA1 gene, is to protect the lung parenchyma from proteolysis by neutrophil elastase. AAT deficiency (AATD) is an autosomal recessive disease, considered as the most important genetic cause of liver disease in children and emphysema in adults. According to frequency, deficient alleles can be classified as "common" (Z and S) and "rare" (Mmalton, Mheerlen, Mprocida etc). Type, intensity and onset of clinical disease associated with AATD occur as a result of interaction between AATD and additional genetic and acquired factors (tobacco smoking, air pollution exposure etc). The most frequent clinical manifestations include premature emphysema, chronic hepatitis, cirrhosis and hepatocellular carcinoma. Epidemiological studies highlight the need for improvement in diagnostic efficiency for AATD. It is recommended for a diagnostic approach to integrate precise, internationally recognized clinical criteria and a standardized laboratory protocol, based on a combination of biochemical and molecular methods. The predilection site of clinical manifestations guides the therapeutic approach. Augmentation therapy is possible in lung disease, while currently the only specific measure in patients with severe liver failure due to AATD is transplantation. In all patients, preventive measures, ammeliorating the deleterious effects of habits and environmental factors are recommended. Introduction of gene therapy is expected to additionally improve health outcomes in affected persons. Current results with an integrative AATD diagnostic strategy in the Serbian population are highly encouraging, prompting towards its further implementation in common medical practice with the ultimate goal to establish a national register of affected individuals

Isoelectrofocusing and PCR Amplification-Reverse Hybridization Assay in Evaluation of Alpha-1-Antitrypsin Deficiency

Alpha-1-antitrypsin deficiency is a potentially lethal genetic disorder, which has pulmonary and liver manifestations. The standardized biochemical and molecular diagnostic protocol for detection of clinically relevant alleles is needed. The paper summarizes current concepts about AATD, describes the potentials of isoelectric focusing and PCR amplification-reverse allele specific oligonucleotide hybridization assay in the detection of affected individuals and shortly presents our experiences in the evaluation of AATD. We conclude that the systematic clinical laboratory approach to AATD might be based on the combination of mentioned methods, coordinated by alpha-1-antritrypsin quantification. Additionally, its complete medical implementation is achieved through teamwork between clinical chemists, molecular biologists and clinicians

Is an integrative laboratory algorithm more effective in detecting alpha-1-antitrypsin deficiency in patients with premature chronic obstructive pulmonary disease than AAT concentration based screening approach?

Introduction: Alpha-1-antitrypsin deficiency (AATD), genetic risk factor for premature chronic obstructive pulmonary disease (COPD), often remains undetected. The aim of our study was to analyse the effectiveness of an integrative laboratory algorithm for AATD detection in patients diagnosed with COPD by the age of 45 years, in comparison with the screening approach based on AAT concentration measurement alone. Subjects and methods: 50 unrelated patients (28 males / 22 females, age 52 (24-75 years) diagnosed with COPD before the age of 45 years were enrolled. Immunonephelometric assay for alpha-1-antitrypsin (AAT) and PCR-reverse hybridization for Z and S allele were first-line, and isoelectric focusing and DNA sequencing (ABI Prism BigDye) were reflex tests. Results: AATD associated genotypes were detected in 7 patients (5 ZZ, 1 ZM(malton), 1 ZQ0(amersfoort)), 10 were heterozygous carriers (8 MZ and 2 MS genotypes) and 33 were without AATD (MM genotype). Carriers and patients without AATD had comparable AAT concentrations (P = 0.125). In majority of participants (48) first line tests were sufficient to analyze AATD presence. In two remaining cases reflex tests identified rare alleles, M-malton and Q0(amersfoort), the later one being reported for the first time in Serbian population. Detection rate did not differ between algorithm and screening both for AATD (P = 0.500) and carriers (P = 0.063). Conclusion: There is a high prevalence of AATD affected subjects and carriers in a group of patients with premature COPD. The use of integrative laboratory algorithm does not improve the effectiveness of AATD detection in comparison with the screening based on AAT concentration alone

Questionable Reliability of Homocysteine As the Metabolic Marker for Folate and Vitamin B12 Deficiency in Patients with Chronic Obstructive Pulmonary Disease

Background: An increased homocysteine (Hcy) concentration may represent a metabolic marker of folate and vitamin B-12 deficiency, both significant public health problems. For different reasons, patients with chronic obstructive pulmonary disease (COPD) are prone to these deficiencies. The study evaluates the reliability of Hcy concentration in predicting folate or vitamin B-12 deficiency in these patients. Methods: A group of 50 COPD patients (28 males/22 females, age ((X) over bar +/- SD=49.0 +/- 14.5) years was enrolled. A chemiluminescent microparticle immunoassay was applied for homocysteine, folate and vitamin B-12 concentration. Kolmogorov-Smirnov, Mann-Whitney U and chi(2) tests, Spearman's correlation and ROC analysis were included in the statistical analysis, with the level of significance set at 0.05. Results: Average (SD) concentrations of folate and vitamin B-12 were 4.13 (2.16) mu g/L and 463.6 (271.0) ng/L, whereas only vitamin B-12 correlated with the Hcy level (P=-0.310 (R=0.029)). Gender related differences were not significant and only a borderline significant correlation between age and folate was confirmed (R=0.279 (P=0.047)). The incidence of folate and vitamin B-12 deficiency differed significantly (P=0.000 and P lt 0.000 for folate and vitamin B12 respectively), depending on the cutoff used for classification (4.4, 6.6 and 8.0 mu g/L folate; 203 and 473 ng/L - vitamin B-12). ROC analyses failed to show any significance of hyperhomocysteinemia as a predictor of folate or vitamin B-12 deficiency. Conclusion: Reliability of the Hcy concentration as a biomarker of folate or vitamin B-12 depletion in COPD patients is not satisfactory, so their deficiency cannot be predicted by the occurrence of HHcy

Is an integrative laboratory algorithm more effective in detecting alpha-1-antitrypsin deficiency in patients with premature chronic obstructive pulmonary disease than AAT concentration based screening approach?

Introduction: Alpha-1-antitrypsin deficiency (AATD), genetic risk factor for premature chronic obstructive pulmonary disease (COPD), often remains undetected. The aim of our study was to analyse the effectiveness of an integrative laboratory algorithm for AATD detection in patients diagnosed with COPD by the age of 45 years, in comparison with the screening approach based on AAT concentration measurement alone. Subjects and methods: 50 unrelated patients (28 males / 22 females, age 52 (24-75 years) diagnosed with COPD before the age of 45 years were enrolled. Immunonephelometric assay for alpha-1-antitrypsin (AAT) and PCR-reverse hybridization for Z and S allele were first-line, and isoelectric focusing and DNA sequencing (ABI Prism BigDye) were reflex tests. Results: AATD associated genotypes were detected in 7 patients (5 ZZ, 1 ZM(malton), 1 ZQ0(amersfoort)), 10 were heterozygous carriers (8 MZ and 2 MS genotypes) and 33 were without AATD (MM genotype). Carriers and patients without AATD had comparable AAT concentrations (P = 0.125). In majority of participants (48) first line tests were sufficient to analyze AATD presence. In two remaining cases reflex tests identified rare alleles, M-malton and Q0(amersfoort), the later one being reported for the first time in Serbian population. Detection rate did not differ between algorithm and screening both for AATD (P = 0.500) and carriers (P = 0.063). Conclusion: There is a high prevalence of AATD affected subjects and carriers in a group of patients with premature COPD. The use of integrative laboratory algorithm does not improve the effectiveness of AATD detection in comparison with the screening based on AAT concentration alone

Anti-TNF treatment and miliary tuberculosis in Crohn’s disease

Introdution. Tumour necrosis factor alpha (TNFα) has a central role in the host immune response to mycobacterial infection. TNFα blockade may therefore result in reactivation of recent or remotely acquired infection. In reported mycobacterium tuberculosis infections, extra-pulmonary and disseminated tuberculosis (TB) was common, appeared rapidly, and if unrecognized, with fatal outcome. We present a female patient with miliary TB following treatment with infliximab for fistulizing Crohn’s disease. Case Outline. Five years before admission, the patient was diagnosed with Crohn’s disease, with inflammation limited to the terminal ileum and sigmoid colon and has been on azathioprine 100 mg/day for the last 10 months. Three months before admission to the hospital she developed an enterocutaneous fistula for which therapy with infliximab was started in addition to azathioprine therapy. A tuberculin skin test and a chest x-ray were performed prior to the first infusion with normal findings. She presented with a 6-week history of fever, weakness, weight-loss and a 2-week dry cough. Chest x-ray and computed tomography displayed remarkable bilateral hilar and mediastinal lymphadenopathy and uniformly distributed fine nodules throughout both lung fields varying in size from 2 to 3 mm, without any signs of cavitation. Since there were clinical and morphological signs that indicated miliary TB, the treatment with antituberculous therapy was started and six weeks later all of the symptoms completely resolved and the lesions visible on x-ray diminished. Conclusion. The clinical use of TNF-inhibitors is associated with increased risk of developing tuberculosis. Physicians should be aware of the increased risk of reactivation of TB among patients treated with anti-TNF agents and regularly look for usual and unusual symptoms of TB