Update on and future perspectives for the diagnosis of alpha-1 antitrypsin deficiency in Brazil / Atualização e perspectivas futuras para o diagnóstico da deficiência de alfa-1 antitripsina no Brasil

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

RESUMO A deficiência de alfa-1 antitripsina (DAAT) é um distúrbio genético raro causado por uma mutação no gene SERPINA1, que codifica o inibidor de protease alfa-1 antitripsina (AAT). A DAAT predispõe os indivíduos a DPOC e doença hepática. O diagnóstico precoce é essencial para a implementação de medidas preventivas e para limitar a carga da doença. Embora diretrizes nacionais e internacionais para o diagnóstico e manejo da DAAT estejam disponíveis há 20 anos, mais de 85% dos casos não são diagnosticados e, portanto, não são tratados. No Brasil, os motivos para o subdiagnóstico da DAAT incluem o desconhecimento dos médicos sobre a condição, a diversidade racial da população, o fato de os níveis séricos de AAT serem avaliados em um número limitado de indivíduos e a falta de ferramentas diagnósticas convenientes. O diagnóstico da DAAT baseia-se em resultados de exames laboratoriais. A abordagem diagnóstica padrão envolve a avaliação dos níveis séricos de AAT, seguida de fenotipagem, genotipagem, sequenciamento gênico ou suas combinações para detecção da mutação específica. Nos últimos 10 anos, novas técnicas foram desenvolvidas, oferecendo uma alternativa rápida, minimamente invasiva e confiável aos métodos tradicionais de teste. Um desses testes disponíveis no Brasil é o teste de genotipagem A1AT, que analisa simultaneamente as 14 mutações mais prevalentes da DAAT usando DNA extraído de swab bucal ou de sangue em papel-filtro. Esses avanços podem contribuir para a superação do problema do subdiagnóstico no Brasil e em outros países, bem como podem aumentar a taxa de detecção da DAAT e, portanto, mitigar os malefícios do diagnóstico tardio.

The patient profile of individuals with Alpha-1 antitrypsine gene mutations at a referral center in Brazil / Perfil dos pacientes com mutação no gene da alfa-1 antitripsina em um centro de referência no Brasil

ABSTRACT Objective: The clinical, functional, radiological and genotypic descriptions of patients with an alpha-1 antitrypsin (A1AT) gene mutation in a referral center for COPD in Brazil. Methods: A cross-sectional study of patients with an A1AT gene mutation compatible with deficiency. We evaluated the A1AT dosage and genotypic, demographic, clinical, tomographic, and functional characteristics of these patients. Results: Among the 43 patients suspected of A1AT deficiency (A1ATD), the disease was confirmed by genotyping in 27 of them. The A1AT median dosage was 45 mg/dL, and 4 patients (15%) had a normal dosage. Median age was 54, 63% of the patients were male, and the respiratory symptoms started at the age of 40. The median FEV1 was 1.37L (43% predicted). Tomographic emphysema was found in 77.8% of the individuals. The emphysema was panlobular in 76% of them and 48% had lower lobe predominance. The frequency of bronchiectasis was 52% and the frequency of bronchial thickening was 81.5%. The most common genotype was Pi*ZZ in 40.7% of participants. The other genotypes found were: Pi*SZ (18.5%), PiM1Z (14.8%), Pi*M1S (7.4%), Pi*M2Z (3.7%), Pi*M1I (3.7%), Pi*ZMnichinan (3.7%), Pi*M3Plowell (3.7%), and Pi*SF (3.7%). We did not find any significant difference in age, smoking load, FEV1, or the presence of bronchiectasis between the groups with a normal and a reduced A1AT dosage, neither for 1 nor 2-allele mutation for A1ATD. Conclusions: Our patients presented a high frequency of emphysema, bronchiectasis and bronchial thickening, and early-beginning respiratory symptoms. The most frequent genotype was Pi*ZZ. Heterozygous genotypes and normal levels of A1AT also manifested significant lung disease.

RESUMO Objetivo: Caracterização clínica, funcional, radiológica e genotípica dos pacientes portadores de mutações do gene da alfa-1 antitripsina (A1AT) em um centro de referência em doença pulmonar obstrutiva crônica (DPOC) no Brasil. Métodos: Estudo transversal de pacientes com mutação no gene da A1AT compatível com deficiência. Foram avaliadas características genotípicas, demográficas, clínicas, tomográficas, de função pulmonar, e dosagem de A1AT. Resultados: De 43 pacientes suspeitos para deficiência de alfa-1 antitripsina (DA1AT), a doença foi confirmada por genotipagem em 27. A mediana da dosagem de A1AT foi de 45 mg/dL, e 4 pacientes (15%) apresentavam dosagens normais. A idade mediana foi de 54 anos, 63% dos participantes eram do sexo masculino e a idade do início dos sintomas prevalente foi aos 40 anos. A mediana do volume expiratório forçado no primeiro segundo (VEF1) foi de 1,37 L (43% do previsto). Enfisema tomográfico foi encontrado em 77,8% dos indivíduos, sendo panlobular em 76% e de predomínio em lobos inferiores em 48%. A frequência de bronquiectasias foi de 52%, e a de espessamento brônquico, de 81,5%. O genótipo mais encontrado foi Pi*ZZ (40,7%). Os demais genótipos foram: Pi*SZ (18,5%), Pi*M1Z (14,8%), Pi*M1S (7,4%), Pi*M2Z (3,7%), Pi*M1I (3,7%), Pi*ZMnichinan (3,7%), Pi*M3Plowell (3,7%) e Pi*SF (3,7%). Não encontramos diferença significativa para idade, carga tabágica, VEF1 e presença de bronquiectasias entre os grupos com dosagem de A1AT normal versus alterada, nem entre 1 alelo versus 2 alelos com mutação para DA1AT. Conclusões: Nossos pacientes apresentaram alta frequência de enfisema, bronquiectasias e espessamento brônquico, com início precoce dos sintomas respiratórios. O genótipo mais frequente foi Pi*ZZ, embora genótipos heterozigotos e níveis normais de A1AT também tenham se manifestado com doença pulmonar significativa.

Déficit de Alfa-1-antitripsina y su tratamiento / Alpha-1 antitrypsin deficiency and its treatment

Alpha-1 antitrypsin deficiency (AATD) is a genetic disorder caused by a mutation in the codifying gene for the alpha-1 antitrypsin (AAT) protein, which has anti-elastase activity. While there is extensive genetic variability, the most common genotypes associated with AATD are PI*Z y PI*S. Most clinical manifestations are pulmonary (i.e. emphysema) and hepatic, though other pathologies, such as panniculitis and Wegener's granulomatosis, can also present with this disorder. To date, there is no cure for AATD, and treatment options are focused on reducing the frequency of exacerbations and relieving symptoms; among these, augmentation therapy, which raises AAT levels through serum injections of the protein to correct the deficit, has been the most effective. Novel findings of this therapy are discussed, along with research efforts that explore new treatment options based on gene therapy or the use of protein chaperones, for instance. In Chile, no epidemiological studies on AATD have been conducted, so it is unknown exactly how many individuals are affected or if they receive adequate treatment. (AU)

Prevalence of alpha-1 antitrypsin deficiency and allele frequency in patients with COPD in Brazil / Prevalência da deficiência de alfa-1 antitripsina e frequência alélica em pacientes com DPOC no Brasil

ABSTRACT Objective: To determine the prevalence of alpha 1-antitrypsin (AAT) deficiency (AATD), as well as allele frequency, in COPD patients in Brazil. Methods: This was a cross-sectional study involving 926 COPD patients 40 years of age or older, from five Brazilian states. All patients underwent determination of AAT levels in dried blood spot (DBS) samples by nephelometry. Those with DBS AAT levels ≤ 2.64 mg/dL underwent determination of serum AAT levels. Those with serum AAT levels of < 113 mg/dL underwent genotyping. In case of conflicting results, SERPINA1 gene sequencing was performed. Results: Of the 926 COPD patients studied, 85 had DBS AAT levels ≤ 2.64 mg/dL, and 24 (2.6% of the study sample) had serum AAT levels of < 113 mg/dL. Genotype distribution in this subset of 24 patients was as follows: PI*MS, in 3 (12.5%); PI*MZ, in 13 (54.2%); PI*SZ, in 1 (4.2%); PI*SS, in 1 (4.2%); and PI*ZZ, in 6 (25.0%). In the sample as a whole, the overall prevalence of AATD was 2.8% and the prevalence of the PI*ZZ genotype (severe AATD) was 0.8% Conclusions: The prevalence of AATD in COPD patients in Brazil is similar to that found in most countries and reinforces the recommendation that AAT levels be measured in all COPD patients.

RESUMO Objetivo: Determinar a prevalência da deficiência de alfa 1-antitripsina (AAT), bem como a frequência alélica, em pacientes com DPOC no Brasil. Métodos: Estudo transversal com 926 pacientes com DPOC, com 40 anos ou mais, oriundos de cinco estados brasileiros. Todos os pacientes foram submetidos a dosagem de AAT em amostras de sangue seco por meio de nefelometria. Aqueles em que a concentração de AAT no sangue seco foi ≤ 2,64 mg/dl foram submetidos a dosagem sérica de AAT. Aqueles em que a concentração sérica de AAT foi < 113 mg/dl foram submetidos a genotipagem. Quando os resultados foram discrepantes, foi realizado o sequenciamento do gene SERPINA1. Dos 926 pacientes com DPOC estudados, 85 apresentaram concentração de AAT em sangue seco ≤ 2,64 mg/dl, e 24 (2,6% da amostra) apresentaram concentração sérica de AAT < 113 mg/dl. A distribuição genotípica nesse subgrupo de 24 pacientes foi a seguinte: PI*MS, em 3 (12,5%); PI*MZ, em 13 (54,2%); PI*SZ, em 1 (4,2%); PI*SS, em 1 (4,2%); e PI*ZZ, em 6 (25,0%). Na amostra estudada, a prevalência global da deficiência de AAT foi de 2,8% e a prevalência do genótipo PI*ZZ (deficiência grave de AAT) foi de 0,8%. Conclusões: A prevalência da deficiência de AAT em pacientes com DPOC no Brasil é semelhante àquela encontrada na maioria dos países e reforça a recomendação de que se deve medir a concentração de AAT em todos pacientes com DPOC.

rare case of alpha 1-antitrypsin deficiency associated with hypogammaglobulinemia and recurrent pulmonary thrombosis

Alpha 1 -antitrypsin [AAT] belongs to the family of serpins [serine protease inhibitors]. Loop sheet polymerization is the pathology behind serpinopathies which encompasses AAT, anti-thrombin III and neuroserpin deficiency. To the best of our knowledge, we report the first case of alpha 1-antitrypsin deficiency associated with hypogammaglobulinemia and recurrent pulmonary thrombosis without any concomitant use of drugs

Validation and development of an immunonephelometric assay for the determination of alpha-1 antitrypsin levels in dried blood spots from patients with COPD / Desenvolvimento e validação de um método de imunonefelometria em amostras de sangue em papel-filtro para a dosagem da alfa-1 antitripsina em pacientes com DPOC

OBJECTIVE: To validate and develop an immunonephelometric assay for the determination of alpha-1 antitrypsin (AAT) levels in dried blood spots from COPD patients in Brazil. METHODS: We determined AAT levels in serum samples and dried blood spots from 192 COPD patients. For the preparation of dried blood spots, a disk (diameter, 6 mm) was placed into a tube, eluted with 200 µL of PBS, and stored overnight at 4ºC. All of the samples were analyzed by immunonephelometry in duplicate. We used the bootstrap resampling method in order to determine a cut-off point for AAT levels in dried blood spots. RESULTS: The correlation coefficient between the AAT levels in serum samples and those in dried blood spots was r = 0.45. For dried blood spots, the cut-off value was 2.02 mg/dL (97% CI: 1.45-2.64 mg/dL), with a sensitivity, specificity, positive predictive value, and negative predictive value of 100%, 95.7%, 27.2%, and 100%, respectively. CONCLUSIONS: This method for the determination of AAT levels in dried blood spots appears to be a reliable screening tool for patients with AAT deficiency. .

OBJETIVO: Validar e desenvolver um método de dosagem de alfa-1 antitripsina (AAT) por imunonefelometria em amostras de sangue em papel-filtro em pacientes com DPOC no Brasil. MÉTODOS: Amostras de soro e de sangue em papel-filtro de 192 pacientes com DPOC foram utilizadas para a dosagem de AAT. Para a preparação das amostras de sangue em papel-filtro, um disco do papel com diâmetro de 6 mm foi colocado em um tubo e eluído com 200 µL de PBS, permanecendo por toda a noite a 4ºC. Todas as amostras foram analisadas em duplicata por imunonefelometria. O método de reamostragem bootstrap foi utilizado para a determinação de um ponto de corte para o nível de AAT nas amostras de sangue em papel-filtro. RESULTADOS: O coeficiente de correlação entre os níveis de AAT em soro e em sangue em papel-filtro foi de r = 0,45. Para as amostras em papel-filtro, o ponto de corte foi de 2,02 mg/dL (IC97%: 1,45-2,64 mg/dL), com sensibilidade, especificidade, valor preditivo positivo e valor preditivo negativo de 100%, 95,7%, 27,2% e 100%, respectivamente. CONCLUSÕES: Este método de determinação dos níveis de AAT em sangue em papel-filtro se mostrou uma ferramenta confiável para o rastreamento de pacientes com deficiência de AAT. .

Identification of Compound Heterozygous Mutation in a Korean Patient with Alpha 1-antitrypsin Deficiency / 대한진단검사의학회지

Alpha 1-antitrypsin (AAT) deficiency is a genetic disorder that primarily affects the lungs and liver. While AAT deficiency is one of the most common genetic disorders in the Caucasian population, it is extremely rare in Asians. Here, we report the case of a 36-year-old Korean woman with AAT deficiency who visited the emergency department of our hospital for the treatment of progressive dyspnea that had begun 10 years ago. She had never smoked. Chest computed tomography revealed panlobular emphysema in both lungs, which suggested AAT deficiency. The serum AAT level was 33 mg/dL (reference interval: 90-200 mg/dL). Four exons of the SERPINA1 gene, which is responsible for AAT deficiency, and their flanking regions were analyzed by PCR-direct sequencing. The patient was found to have 1 missense mutation (c.230C>T, p.Ser77Phe; Siiyama) and 1 frameshift mutation (c.1158dupC, p.Glu387ArgfsX14; QOclayton). This is the first Korean case of AAT deficiency confirmed by genetic analysis and the second case of a compound heterozygote of Siiyama and QOclayton, the first case of which was reported from Japan.

Deficiência de alfa-1 antitripsina: diagnóstico e tratamento / Alpha-1 antitrypsin deficiency: diagnosis and treatment

A deficiência de alfa-1 antitripsina é um distúrbio genético de descoberta recente e que ocorre com freqüência comparável à da fibrose cística. Resulta de diferentes mutações no gene SERPINA1 e tem diversas implicações clínicas. A alfa-1 antitripsina é produzida principalmente no fígado e atua como uma antiprotease. Tem como principal função inativar a elastase neutrofílica, impedindo a ocorrência de dano tecidual. A mutação mais freqüentemente relacionada à doença clínica é o alelo Z, que determina polimerização e acúmulo dentro dos hepatócitos. O acúmulo e a conseqüente redução dos níveis séricos de alfa-1 antitripsina determinam, respectivamente, doença hepática e pulmonar, sendo que esta se manifesta principalmente sob a forma de enfisema de aparecimento precoce, habitualmente com predomínio basal. O diagnóstico envolve a detecção de níveis séricos reduzidos de alfa-1 antitripsina e a confirmação fenotípica. Além do tratamento usual para doença pulmonar obstrutiva crônica, existe atualmente uma terapia específica com infusão de concentrados de alfa-1 antitripsina. Essa terapia de reposição, aparentemente segura, ainda não teve a eficácia clínica definitivamente comprovada, e o custo-efetividade também é um tema controverso e ainda pouco abordado. Apesar da sua importância, não existem dados epidemiológicos brasileiros a respeito da prevalência da doença ou da freqüência de ocorrência dos alelos deficientes. O subdiagnóstico também tem sido uma importante limitação tanto para o estudo da doença quanto para o tratamento adequado dos pacientes. Espera-se que a criação do Registro Internacional de Alfa-1 venha a resolver essas e outras importantes questões.

Alpha-1 antitrypsin deficiency is a recently identified genetic disease that occurs almost as frequently as cystic fibrosis. It is caused by various mutations in the SERPINA1 gene, and has numerous clinical implications. Alpha-1 antitrypsin is mainly produced in the liver and acts as an antiprotease. Its principal function is to inactivate neutrophil elastase, preventing tissue damage. The mutation most commonly associated with the clinical disease is the Z allele, which causes polymerization and accumulation within hepatocytes. The accumulation of and the consequent reduction in the serum levels of alpha-1 antitrypsin cause, respectively, liver and lung disease, the latter occurring mainly as early emphysema, predominantly in the lung bases. Diagnosis involves detection of low serum levels of alpha-1 antitrypsin as well as phenotypic confirmation. In addition to the standard treatment of chronic obstructive pulmonary disease, specific therapy consisting of infusion of purified alpha-1 antitrypsin is currently available. The clinical efficacy of this therapy, which appears to be safe, has yet to be definitively established, and its cost-effectiveness is also a controversial issue that is rarely addressed. Despite its importance, in Brazil, there are no epidemiological data on the prevalence of the disease or the frequency of occurrence of deficiency alleles. Underdiagnosis has also been a significant limitation to the study of the disease as well as to appropriate treatment of patients. It is hoped that the creation of the Alpha One International Registry will resolve these and other important issues.

Diagnosis of alpha-1-antitrypsin deficiency by DNA analysis of children with liver disease

BACKGROUND: Alpha-1-antitrypsin deficiency is a genetic disorder which is transmitted in a co-dominant, autosomal form. Alpha-1-antitrypsin deficiency affects mainly the lungs and the liver leading, in the latter case, to neonatal cholestasis, chronic hepatitis or cirrhosis. A precise diagnosis of Alpha-1-antitrypsin deficiency may be obtained by biochemical or molecular analysis. OBJECTIVE: The purpose of this study was to use DNA analysis to examine the presence of an alpha-1-antitrypsin deficiency in 12 children suspected of having this deficiency and who showed laboratory and clinical characteristics of the disease. PATIENTS AND METHODS: Twelve patients, aged 3 months to 19 years, who had serum alpha-1-antitrypsin levels lower than normal and/or had hepatic disease of undefined etiology were studied. The mutant alleles S and Z of the alpha-1-antitrypsin gene were investigated in the 12 children. Alpha-1-antitrypsin gene organization was analyzed by amplification of genoma through the polymerase chain reaction and digestion with the restriction enzymes Xmnl (S allele) and Taq-1 (Z allele). RESULTS: Seven of the 12 patients had chronic liver disease of undefined etiology and the other five patients had low serum levels of alpha-1-antitrypsin as well as a diagnosis of neonatal cholestasis and/or chronic liver disease of undefined etiology. Five of the 12 patients were homozygous for the Z allele (ZZ) and two had the S allele with another allele (*S) different from Z. CONCLUSION: These results show that alpha-1-antitrypsin deficiency is relatively frequent in children with chronic hepatic disease of undefined etiology and/or low alpha-1-antitrypsin levels (41.6 per cent). A correct diagnosis is important for effective clinical follow-up and for genetic counseling.