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Alpha 1-antitrypsin deficiency

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Mazia Fatima, MBBS [2]

Synonyms and keywords:: Alpha-1-deficiency; Anti-protease deficiency;

For patient information, click here Template:DiseaseDisorder infobox

Overview


Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Mazia Fatima, MBBS [2]

Overview

Alpha 1-antitrypsin deficiency (A1AD or Alpha-1) is a genetically inherited disorder that results in defective production of alpha 1-antitrypsin. Alpha 1-antitrypsin deficiency (A1AD) was discovered in 1963 by Carl-Bertil Laurell and Eriksson at the University of Lund, Sweden. In 1969, Sharp et al was the first to discover the association between liver disease and development of A1AD. There is no established system for the classification of alpha 1-antitrypsin deficiency. Alpha 1-antitrypsin (A1AT) is synthesized and secreted mainly by hepatocytes. Alpha 1-antitrypsin (A1AT) protects the lungs from proteases like the neutrophil elastase enzyme. Genetic mutation in the SERPINA1 gene results in decreased levels of alveolar alpha1 antitrypsin. Proteases accumulate in the alveoli causing a destruction of alveolar walls and resultant emphysema. Accumulation of alpha1-antitrypsin in hepatocytes results in chronic liver disease. Panacinar emphysema is commonly associated with AATD with loss of all portions of the acinus from the respiratory bronchiole to the alveoli. In alpha1-antitrypsin deficiency (AATD), the emphysematous areas are uniformly distributed throughout the lobule found more commonly in the basilar portions of the lung. Alpha 1-antitrypsin deficiency has to be differentiated from other conditions with similar presentation like autoimmune hepatitis, bronchiectasis, bronchitis, chronic obstructive pulmonary disease (COPD), cystic fibrosis, emphysema, primary ciliary dyskinesia (Kartagener Syndrome), viral hepatitis. Alpha 1-antitrypsin deficiency (A1AD) is more common in people of Northern European, Iberian, and Saudi Arabian descent. First degree relatives of patients with known AAT deficiency are at an increased risk for the condition. Smoking is risk factor for development of serious lung disease in patients with AAT deficiency. Risk for lung disease also increases with exposure to dust, fumes, or other toxic substances. According to the Spanish Society of Pneumology and Thoracic Surgery (SEPAR), all COPD patients should be screened for AATD at least once in their lifetime. All patients with unexplained liver disease with or without respiratory symptoms should be evaluated for alpha1-antitrypsin deficiency AATD. If left untreated, not all patients with deficient gene develop symptomatic emphysema or cirrhosis. The symptoms of alpha1-antitrypsin deficiency (AATD) in the first two decades of life are mainly of associated liver disease progressing to pulmonary manifestations appear later in life. Emphysema is seen in nonsmokers in the fifth decade of life and during the fourth decade of life in smokers. Less common associations are panniculitis and cytoplasmic antineutrophil antibody‒positive vasculitis. The most common cause of death is emphysema. Chronic liver disease is the second most common cause of death. Common complications of AATD include pneumothorax, pneumonia, acute exacerbation of airflow obstruction, and respiratory failure. Physical examination of patients with AATD is usually remarkable for signs characteristic of increased respiratory work, airflow obstruction and hyperinflation that varies according to the severity of emphysema. A reduced concentration of serum alpha1-antitrypsin levels is diagnostic of AATD. Laboratory findings consistent with the diagnosis of AATD include moderate-to-severe airflow obstruction with an FEV1 in the range of 30-40% of the predicted value, reduced vital capacity, increased lung volumes secondary to air trapping (residual volume >120% of predicted value) are usually present, and diffusing capacity values are reduced substantially (<50% of predicted value) in most symptomatic patients. On chest X-ray alpha1-antitrypsin deficiency (AATD) emphysema presents as a hyperlucent appearance because healthy tissue has been destroyed. On High-resolution CT (HRCT) scan of the chest, hypoattenuated areas resulting from a lack of lung tissue are panlobular and characteristic lower zone predominance. Patients with low or borderline serum levels are tested with phenotyping (serum levels < 100 mg/dL) by isoelectric focusing (IEF) is the most commonly used method to definitively detect the alpha1-antitrypsin phenotype that indicates a risk for AATD. Genotyping uses DNA extracted from circulating mononuclear blood cells that utilizes DNA amplification techniques with melt-curve analysis. Recommendations based on treatment guidelines for AATD include: Alpha 1-antitrypsin enzyme repletion, smoking cessation, long-acting inhaled bronchodilators, preventive vaccinations against influenza and pneumococcus, pulmonary rehabilitation for patients with functional impairment, supplemental oxygen if needed, lung transplantation, treatment of COPD exacerbation in all patients of AATD should include AAT repletion. Lung transplantation may be recommended for some patients with end-stage lung disease. Effective measures for the primary prevention of alpha 1-antitrypsin deficiency includes vaccination against hepatitis A and hepatitis B to decrease the risk of liver complications. Secondary prevention strategies following alpha1-antitrypsin deficiency (AATD) includes avoid cigarette smoking. Smoking accelerates the progression of emphysema in severely deficient individuals by as much as 15 years when compared to their nonsmoking controls. The ATS/ERS AAT Deficiency Task Force recommends that all exacerbations with purulent sputum be treated with early antibiotic therapy. Prompt and effective treatment of infections provides protection from additional lung injury from an influx of neutrophils into the alveolus.

Historical Perspective

Alpha 1-antitrypsin deficiency (A1AD) was discovered in 1963 by Carl-Bertil Laurell (1919–2001) and Eriksson at the University of Lund, Sweden. In 1969, Sharp et al were the first to discover the association between liver disease and development of A1AD.

Classification

There is no established system for the classification of alpha 1-antitrypsin deficiency.

Pathophysiology

Alpha 1-antitrypsin (A1AT) is synthesized and secreted mainly by hepatocytes. However, other sources of the enzyme include macrophages and bronchial epithelial cells.Alpha1-antitrypsin enzyme is a member of the serine protease inhibitor (serpin) family of proteins. Alpha 1-antitrypsin (A1AT) protects the lungs from proteases like the neutrophil elastase enzyme.Genetic mutation in the SERPINA1 gene results in decreased levels of alveolar alpha1 antitrypsin. Proteases accumulate in the alveoli causing a destruction of alveolar walls and resultant emphysema. Excess alpha1-antitrypsin in hepatocytes results in chronic liver disease. SERPINA1 gene mutation alters the configuration of the alpha1-antitrypsin molecule and prevents its release from hepatocytes. By far, the most common severe deficient variant is the Z allele, which is produced by substitution of a lysine for glutamate at position 342 of the molecule. This accounts for 95% of the clinically recognized cases of severe alpha-1 AT deficiency. On cut section of the lung, emphysematous process is evidenced by dilated air spaces and loss of lung parenchyma. Superimposed infections can result in scarring. Panacinar emphysema is commonly associated with AATD with loss of all portions of the acinus from the respiratory bronchiole to the alveoli. In alpha1-antitrypsin deficiency (AATD), the emphysematous areas are uniformly distributed throughout the lobule found more commonly in the basilar portions of the lung.

Differentiating Alpha 1-antitrypsin deficiency from Other Diseases

Alpha 1-antitrypsin deficiency has to be differentiated from other conditions with similar presentation like autoimmune hepatitis, bronchiectasis, bronchitis, chronic obstructive pulmonary disease (COPD), cystic fibrosis, emphysema, primary ciliary dyskinesia (Kartagener syndrome), and viral hepatitis.

Epidemiology and Demographics

Alpha 1-antitrypsin deficiency (A1AD) is more common in people of Northern European, Iberian, and Saudi Arabian descent. Most researchers believe it is markedly underrecognized. The incidence of AATD is estimated to be 20 cases per 100,000 individuals worldwide. The prevalence of AATD is estimated to be 70,000-100,000 cases annually. Alpha1-antitrypsin deficiency (AATD) is one of most common lethal genetic diseases among the adult white population. AATD has estimated 117 million carriers and 3.4 million affected individuals.

Risk Factors

First degree relatives of patients with known AAT deficiency are at an increased risk for the condition. Smoking is a risk factor for the development of serious lung disease in patients with AAT deficiency. The risk for lung disease also increases with exposure to dust, fumes, or other toxic substances.

Screening

According to the Spanish Society of Pneumology and Thoracic Surgery (SEPAR), all COPD patients should be screened for AATD at least once in their lifetime. All patients with an unexplained liver disease with or without accompanying respiratory symptoms should be evaluated for AATD.

Natural History, Complications, and Prognosis

If left untreated, not all patients with deficient gene develop symptomatic emphysema or cirrhosis. In symptomatic patients, the median time between observation of symptoms and diagnosis is approximately 8 years. The symptoms of alpha1-antitrypsin deficiency (AATD) in the first two decades of life are mainly of the associated liver disease progressing to pulmonary manifestations appear later in life. Emphysema, is seen in nonsmokers in the fifth decade of life and during the fourth decade of life in smokers. Less common associations are panniculitis and cytoplasmic antineutrophil cytoplasmic antibody-positive vasculitis. The most common cause of death is emphysema. Chronic liver disease is the second most common cause of death. Common complications of AATD include pneumothorax, pneumonia, acute exacerbation of airflow obstruction, and respiratory failure. Prognosis depends on how patients are identified. Patients identified as a result of screening often have an excellent prognosis. Those identified because of their symptoms have a poor prognosis.

Diagnosis

Diagnostic Criteria

A reduced concentration of serum alpha 1-antitrypsin levels is diagnostic of alpha 1-antitrypsin deficiency (AATD).

History and Symptoms

Alpha 1-antitrypsin deficiency (A1AD) may be slow to manifest in symptom onset in newborns. As patient ages, liver dysfunction will occur. The hallmark of AATD is dyspnea. A positive history of dyspnea and liver cirrhosis or chronic hepatitis is suggestive of AATD. The presentation of the disease varies depending on the type of mutation associated with AATD. Symptoms of alpha-1 antitrypsin deficiency include shortness of breath, wheezing, rhonchi and rales (may appear to be due to recurring respiratory infections), and obstructive asthma that does not respond to treatment.

Physical Examination

Physical examination of patients with AATD is usually remarkable for signs characteristic of increased respiratory work, airflow obstruction and hyperinflation that varies according to the severity of emphysema. Patients with mild emphysema usually have no abnormal findings on physical examination. Patient may appear normal. Those with severe emphysema develop tachypnea and pursed-lip breathing. Other findings on physical examination include pulsus paradoxus, scalene muscle retraction, intercostal muscle retraction, wheezing, hepatomegaly, hyperinflation results in barrel chest, increased percussion note, decreased breath sound intensity, and distant heart sounds.

Laboratory Findings

A reduced concentration of serum alpha1-antitrypsin levels is diagnostic of AATD. Laboratory findings consistent with the diagnosis of AATD include moderate-to-severe airflow obstruction with an FEV1 in the range of 30-40% of the predicted value, reduced vital capacity, increased lung volumes secondary to air trapping (residual volume >120% of predicted value) are usually present, diffusing capacity values are reduced substantially (<50% of predicted value) in most symptomatic patients. Serum alpha1-antitrypsin levels are determined by nephelometry. Serum testing is used for diagnostic testing in those patients with family histories compatible with alpha1-antitrypsin deficiency or with siblings with known alpha1-antitrypsin deficiency. In patients with clinical features that are highly suggestive of alpha1-antitrypsin deficiency but whose serum levels are within the reference range the next best step is to perform a functional assay of alpha1 antiprotease, which measures the ability of the patient’s serum to inhibit human leukocyte elastase. Perform liver function tests in patients with low or borderline levels of alpha1-antitrypsin. Measurement of serum transaminases, bilirubin, albumin, and routine clotting function (activated partial thromboplastin time and international normalized ratio).

Imaging Findings

X-ray

On chest Xray of Alpha1-antitrypsin deficiency (AATD), emphysema presents as a hyperlucent appearance because the healthy tissue has been destroyed. Affected regions can also present as oligemic areas on x-ray because they lack the normal rich pattern of branching blood vessels. A characteristic feature observed in about two thirds of PiZZ patients of alpha1-antitrypsin deficiency is that the emphysema has a striking basilar distribution. In contrast, cigarette smoking is associated with a more severe apical disease.

CT scan

On High-resolution CT (HRCT) scan of the chest, hypoattenuated areas result from a lack of lung tissue. As tissue is lost, pulmonary vessels appear smaller, fewer in number, and spread farther apart. Mild forms of alpha1-antitrypsin disease can be missed on HRCT scanning. However, when the disease is moderate, panlobular and characteristic lower zone predominance is observed. Severe forms may be indistinguishable from severe centrilobular emphysema. normal lung structures have been replaced by abnormal airspaces CT of the abdomen shows evidence of hepatomegaly or cirrhosis or hepatocellular carcinoma.

Other Diagnostic Studies

Patients with low or borderline serum levels are tested with phenotyping (serum levels < 100 mg/dL) by isoelectric focusing (IEF) is the most commonly used method to definitively detect the alpha1-antitrypsin phenotype that indicates a risk for AATD. Genotyping uses DNA extracted from circulating mononuclear blood cells that utilize DNA amplification techniques with melt-curve analysis.

Treatment

Medical Therapy

Treatment guidelines for AATD include: alpha 1 antitrypsin enzyme repletion, smoking cessation, long-acting inhaled bronchodilators, preventive vaccinations against influenza and pneumococcus, pulmonary rehabilitation for patients with functional impairment, supplemental oxygen if needed, lung transplantation, treatment of COPD exacerbation in all patients of AATD should include AAT repletion.

Surgery

Lung transplantation may be recommended for some patients with end-stage lung disease. Alpha 1-antitrypsin deficiency accounts for about 5% of all lung transplantation performed in the United States. Five year survival rates following lung transplant is approximately 50%. The rate of FEV1 decline among AATD patients who received double lung transplantation was faster than among single lung recipients. The estimated median survival time was 11 years in transplant recipients versus 5 years in controls. Lung volume reduction surgery (LVRS) can help relieve dyspnea and improve exercise capacity in patients with emphysema. Data regarding the efficacy of LVRS for individuals with AATD is limited and generally less favorable in magnitude and duration of FEV1 improvement.

Primary Prevention

Effective measures for the primary prevention of alpha 1-antitrypsin deficiency includes vaccination against hepatitis A and B is recommended to decrease the risk of liver disease.

Secondary Prevention

Secondary prevention strategies following alpha1-antitrypsin deficiency (AATD) includes avoiding cigarette smoke. Smoking accelerates the progression of emphysema in severely alpha 1 antitrypsin deficient individuals by as much as 15 years when compared to their nonsmoking controls. Pneumonia and annual influenza vaccines will help prevent respiratory infections in patients with alpha1-antitrypsin deficiency (AATD). The ATS/ERS AAT Deficiency Task Force recommends that all exacerbations with purulent sputum be treated with early antibiotic therapy. Prompt and effective treatment of infections may provide protection from additional lung injury from an influx of neutrophils into the alveolus.

Future or Investigational therapies

Treatment options for alpha 1-antitrypsin deficiency currently being studied include recombination and inhaled forms of alpha 1-antitrypsin. Other experimental therapies are aimed at the prevention of polymer formation in the liver. Gene therapy to deliver recombinant adeno-associated virus carrying the human AAT (alpha 1 antitrypsin) gene is also being investigated as an alternate treatment approach.

References


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Historical Perspective

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Mazia Fatima, MBBS [2]

Overview

Alpha 1-antitrypsin deficiency (A1AD) was discovered in 1963 by Carl-Bertil Laurell (1919–2001) and Eriksson at the University of Lund, Sweden. In 1969, Sharp et al was the first to discover the association between liver disease and development of A1AD.

Historical Perspective

  • In 1963, Carl-Bertil Laurell (1919–2001) and Eriksson at the University of Lund, Sweden was the first to discover A1AD at the General Hospital in Malmö, Sweden.[1][2]
  • Laurell, along with a medical resident, Sten Eriksson, observed the absence of the α1 band on protein electrophoresis in samples of patients. 60% of these patients were had developed emphysema at a young age.
  • In 1964, Gross described the animal model of emphysema caused by intratracheally instilled papain.
  • In 1967, Fagerhol described associated allelic variation of AAT.
  • In 1967, Janoff described neutrophil elastase.
  • In 1969, Sharp described association with neonatal cirrhosis. Sharp et al was the first to discover the association between liver disease and development of A1AD.

References

  1. Laurell CB, Eriksson S (1963). “The electrophoretic alpha 1-globulin pattern of serum in alpha 1-antitrypsin deficiency”. Scand J Clin Lab Invest. 15: 132&ndash, 140.
  2. Sharp H, Bridges R, Krivit W, Freier E (1969). “Cirrhosis associated with alpha-1-antitrypsin deficiency: a previously unrecognized inherited disorder”. J Lab Clin Med. 73 (6): 934–9. PMID 4182334.


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Classification

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Mazia Fatima, MBBS [2]

Overview

There is no established system for the classification of alpha 1-antitrypsin deficiency.

Classification

There is no established system for the classification of alpha 1-antitrypsin deficiency.

References


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Pathophysiology

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Mazia Fatima, MBBS [2]

Overview

Alpha 1-antitrypsin (A1AT) is synthesized and secreted mainly by hepatocytes. Alpha1-antitrypsin enzyme is a member of the serine protease inhibitor (serpin) family of proteins. Alpha 1-antitrypsin (A1AT) protects the lungs from proteases like the neutrophil elastase enzyme. A genetic mutation in the SERPINA1 gene results in decreased levels of alveolar alpha1 antitrypsin. Proteases accumulate in the alveoli causing a destruction of alveolar walls and resultant emphysema. Acculmulation of excess alpha1-antitrypsin in hepatocytes results in chronic liver disease. SERPINA1 gene mutation alters the structure of the alpha1-antitrypsin molecule and prevents its release from hepatocytes. By far, the most common severe deficient variant is the Z allele, which is produced by lysine substitution for glutamate at 342 position in the alpha 1-antitrypsin molecule. The Z allele accounts for 95% of the clinically recognized cases of severe alpha-1 AT deficiency. On cut section of the lung, emphysematous process is evidenced by dilated air spaces and loss of lung parenchyma. Superimposed infections can result in scarring. Panacinar emphysema is commonly associated with AATD with loss of all portions of the acinus from the respiratory bronchiole to the alveoli. In alpha1-antitrypsin deficiency (AATD), the emphysematous areas are uniformly distributed throughout the lobule found more commonly in the basilar portions of the lung.

Pathophysiology

The pathophysiology of alpha 1-antitrypsin deficiency (AATD) may be described as follows:[1][2][3]

Lung

Liver

Genetics

  • Alpha1-antitrypsin deficiency (AATD) is inherited in an autosomally-codominant pattern caused by mutations in the SERPINA1 gene.[4]
  • Normal blood levels of alpha-1 antitrypsin are 1.5-3.5 gm/l.
  • The alpha-1 AT gene is located on the long arm of chromosome 14 (gene locus:14q32.1). The SERPINA1 gene has six introns, seven axons and 12.2kb in length. There have been 120 different alleles for alpha-1 AT variants that have been described, but only 10-15 are associated with severe alpha-1 deficiency.
  • Each allele has been given a letter code based upon electrophoretic mobility that varies according to protein charge from amino acid alterations on gel electrophoresis that is used to identify the PI phenotype.
  • SERPINA1 gene mutation alters the configuration of the alpha1-antitrypsin molecule and prevents its release from hepatocytes. By far, the most common severe deficient variant is the Z allele, which is produced by substitution of a lysine for glutamate at position 342 of the molecule. This accounts for 95% of the clinically recognized cases of severe alpha-1 AT deficiency.
  • The 75 alleles can basically be divided into four groups:
    • Normal – M alleles (normal phenotype is MM), found in 90% of the U.S. population, patients have normal lung function.
    • Deficient – Z allele (carried by 2-3% of the U.S. Caucasian population), have plasma levels of alpha-1 AT that is < 35% of normal.
    • Null (Z) – No detectable alpha-1 AT. Least common and most severe form of the disease.
    • Dysfunctional (S) – Patients have a normal alpha-1 AT level, but the enzyme does not function properly.
  • The most common allele is the M allele which codes for protease inhibitor (Pi) M protein.
  • The most common severe deficiency allele is the Z allele which, in the homozygous state (PiZZ).
  • The S allele is associated with AAT plasma levels approximately 60% of normal in the homozygous state.
  • In individuals with PiSS, PiMZ and PiSZ phenotypes, blood levels of A1AT are reduced to between 40 and 60% of normal levels, sufficient to protect the lungs from the effects of elastase in people who do not smoke.
  • In individuals with the PiZZ phenotype, A1AT levels are less than 15 % of normal, and patients are likely to develop emphysema at a young age; 50 % of these patients will develop liver cirrhosis, because the A1AT is not secreted properly and instead accumulates in the liver.
  • A liver biopsy of affected cases will reveal Periodic acid-Shiff (PAS)-positive, diastase-negative granules.
  • Differences in speed of migration of different protein variants on gel electrophoresis have been used to identify the PI phenotype, and these differences in migration relate to variations in protein charge resulting from amino acid alterations.
  • The M allele results in a protein with a medium rate of migration; the Z form of the protein has the slowest rate of migration.
  • Some individuals inherit null alleles that result in protein levels that are not detectable.
  • The S variant occurs at a frequency of 0.02–0.03 and is associated with mild reductions in serum AAT levels.
  • The Z variant is associated with a severe reduction in serum AAT levels. The most common alleles are the M variants with allele frequencies of greater than 0.95 and normal AAT levels.

Molecular Biology

Associated Conditions

α1-antitrypsin deficiency has been associated with a number of diseases:

Gross Pathology

Microscopic Pathology

  • Emphysema results in destruction of alveolar walls and permanent abnormal enlargement of the airspace distal to the terminal bronchiole. [5]
  • In alpha1-antitrypsin deficiency (AATD), the emphysematous areas are uniformly distributed throughout the lobule found more commonly in the basilar portions of the lung.
  • In contrast, emphysema resulting from cigarette smoking characteristically involves the centrilobular lung and respiratory bronchioles in the central portion of the lobule, initially at the apex of the lung.

References

  1. Stoller JK, Aboussouan LS (2012). “A review of α1-antitrypsin deficiency”. Am. J. Respir. Crit. Care Med. 185 (3): 246–59. doi:10.1164/rccm.201108-1428CI. PMID 21960536.
  2. Stoller JK, Brantly M (2013). “The challenge of detecting alpha-1 antitrypsin deficiency”. COPD. 10 Suppl 1: 26–34. doi:10.3109/15412555.2013.763782. PMID 23527684.
  3. Stoller JK (2016). “Alpha-1 antitrypsin deficiency: An underrecognized, treatable cause of COPD”. Cleve Clin J Med. 83 (7): 507–14. doi:10.3949/ccjm.83a.16031. PMID 27399863.
  4. “The genetics of α1-antitrypsin: a family study in England and Scotland – COOK – 1975 – Annals of Human Genetics – Wiley Online Library”.
  5. Greene DN, Elliott-Jelf MC, Straseski JA, Grenache DG (2013). “Facilitating the laboratory diagnosis of α1-antitrypsin deficiency”. Am. J. Clin. Pathol. 139 (2): 184–91. doi:10.1309/AJCP6XBK8ULZXWFP. PMID 23355203.


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Causes

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Mazia Fatima, MBBS [2]

Overview

Alpha1-antitrypsin deficiency (AATD) is caused by a mutation in the SERPINA1 gene. SERPINA1 is located on chromosome 14.

Causes

References

  1. Hazari YM, Bashir A, Habib M, Bashir S, Habib H, Qasim MA, Shah NN, Haq E, Teckman J, Fazili KM (2017). “Alpha-1-antitrypsin deficiency: Genetic variations, clinical manifestations and therapeutic interventions”. Mutat. Res. 773: 14–25. doi:10.1016/j.mrrev.2017.03.001. PMID 28927525.
  2. Stoller JK (2016). “Alpha-1 antitrypsin deficiency: An underrecognized, treatable cause of COPD”. Cleve Clin J Med. 83 (7): 507–14. doi:10.3949/ccjm.83a.16031. PMID 27399863.


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Differentiating Alpha 1-antitrypsin deficiency from other Diseases

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Mazia Fatima, MBBS [2]

Overview

Alpha 1-antitrypsin deficiency has to be differentiated from other conditions with similar presentation like autoimmune hepatitis, bronchiectasis, bronchitis, chronic obstructive pulmonary disease (COPD), cystic fibrosis, emphysema, primary ciliary dyskinesia (Kartagener Syndrome), viral hepatitis.

Differentiating Alpha 1-antitrypsin deficiency from Other Diseases

Alpha 1-antitrypsin deficiency presents with symptoms of emphysema associated with compromised liver function tests and/or cirrhosis. Differential diagnosis of jaundice and RUQ pain includes:

Jaundice and RUQ pain differential diagnosis are:

Classification of jaundice based on etiology Disease History and clinical manifestations Diagnosis
Lab Findings Other blood tests Other diagnostic
Family history Fever RUQ Pain Pruritis Hepatomegaly AST ALT ALK BLR Indirect BLR Direct Viral serology
Jaundice Hepatocellular Jaundice Hemochromatosis + -/+ + ↑/N ↑/N N Ferritin Liver biopsy
Wilson’s disease + -/+ + N ↑/N N Serum cerulloplasmin Liver biopsy
Alcoholic hepatitis -/+ -/+ + ↑↑ N ↑/N N
Cirrhosis -/+ -/+ -/+ -/+ ↑/N ↑/N ↑/N -/+ Thrombocytopenia hypotrophied liver on ultrasound
Alpha 1-antitrypsin deficiency + -/+ -/+ + ↑/N ↑/N ↑/N Serum alpha1-antitrypsin levels decreased Hepatomegaly on CT
Cholestatic Jaundice Common bile duct stone -/+ + + -/+ N N N Dilated ducts on sonography CT/ERCP
Hepatitis A cholestatic type -/+ + + -/+ N N N + HAV- AB Abdominal ultrasound
EBV / CMV hepatitis -/+ + + -/+ N N N + Positive serology
Primary biliary cirrhosis -/+ -/+ + -/+ N/↑ N/↑ N AMA positive Liver biopsy
Primary sclerosing cholangitis -/+ -/+ + -/+ N/↑ N/↑ N Beading on MRCP Liver biopsy
Pancreatic carcinoma + -/+ -/+ N/↑ N/↑ N Mass on ultrasound CT scan for diagnosis

The differential diagnosis of jaundice, fever, and RUQ pain are:

Classification of jaundice based on etiology Disease History and clinical manifestations Diagnosis
Lab Findings Other blood tests Other diagnostic
Family history Fever RUQ Pain Pruritis Hepatomegaly AST ALT ALK BLR Indirect BLR Direct Viral serology
Jaundice Hepatocellular Jaundice Alcoholic hepatitis -/+ -/+ + ↑↑ N ↑/N N
Cirrhosis -/+ -/+ -/+ -/+ ↑/N ↑/N ↑/N -/+ Thrombocytopenia Small liver on ultrasound
Alpha 1-antitrypsin deficiency + -/+ -/+ + ↑/N ↑/N ↑/N Serum alpha1-antitrypsin levels decreased Hepatomegaly on CT
Cholestatic Jaundice Hepatitis A cholestatic type -/+ + + -/+ N N N + HAV- AB Abdominal ultrasound
EBV / CMV hepatitis -/+ + + -/+ N N N + Positive serology PCR or ELISA

Differential diagnosis of cough with wheezes is :

Diseases Symptoms Signs Diagosis
Fever Cough Chest pain Wheezes Crackles Tachypnea Lab tests Imaging
Asthma Dry/Productive + +
  • CT scan shows:
    • Dilated bronchi.
    • Bronchial wall thickening.
    • Air trapping.
Bronchiolitis +/- Dry + + +/-
COPD + Productive + + +
Bacterial pneumonia + Productive + + + +/-
Cystic Fibrosis +/- Productive +/- + Cystic fibrosis transmembrane conductance regulator (CFTR) dysfunction evidenced by : X-ray :

Hyperinflation presents as:

  • Anterior bowing of the infant sternum.
  • Increased retrosternal air space.
  • Generalized pulmonary overinflation.
  • Multiple nodular densities represent mucus plugging and may present in finger-in-glove shape or as a combination of V- or Y-shaped branching and bandlike shadows.

Abdominal findings include dilated multiple loops of the small bowel are seen in neonatal meconium ileus.

Emphysema +/- Productive + +/- + Chest X-ray reveals signs of emphysema include:
  • Increased retrosternal air space (see on lateral chest films).
  • A long narrow heart shadow.
  • Tapering vascular shadows.
  • Hyperlucency of the lungs.
Primary Ciliary Dyskinesia (Kartagener Syndrome) +/- Productive + + + Chest X-ray reveals :
Alpha 1-antitrypsin deficiency +/- Productive + + + Chest X-ray Alpha1-antitrypsin deficiency (AATD) emphysema presents as:
  • a hyperlucent appearance because healthy tissue has been destroyed.
  • Affected regions also are described as oligemic because they lack the normal rich pattern of branching blood vessels.
  • An unusual characteristic in alpha1-antitrypsin deficiency is found in about 60% of PiZZ patients is a striking basilar distribution.
  • In contrast, cigarette smoking is associated with more severe apical disease.

AATD can present as neonatal jaundice. The differential diagnosis for neonatal jaundice is: [3]

Etiology Of Neonatal Jaundice History and clinical manifestations Diagnosis
Lab Findings Other blood tests Other diagnostic
Family history Fever RUQ Pain Pruritis AST ALT ALK BLR Indirect BLR Direct Viral serology
Alpha-1 antitrypsin deficiency + -/+ -/+ N Genetic testing Liver biopsy
Breast feeding failure jaundice
Breast Milk Jaundice
Crigler-Najjar type 2 + N N N Genetic testing
Gilbert Syndrome + N N N Genetic testing
Rotor syndrome + N N N N Genetic testing Liver biopsy
Dubin-Johnson syndrome + N N N N Genetic testing Liver biopsy
Hereditory spherocytosis + -/+ N N N N Genetic testing Osmotic fragility
G6PD deficiency + N N N N Genetic testing
Thalassemia + N N N N Genetic testing
Sickle cell disease + N N N N Genetic testing
Immune hemolysis -/+ N N N N Autoantibodies

References

  1. Ghanei M, Tazelaar HD, Chilosi M, Harandi AA, Peyman M, Akbari HM; et al. (2008). “An international collaborative pathologic study of surgical lung biopsies from mustard gas-exposed patients”. Respir Med. 102 (6): 825–30. doi:10.1016/j.rmed.2008.01.016. PMID 18339530.
  2. Lazović B, Svenda MZ, Mazić S, Stajić Z, Delić M (2013). “Analysis of electrocardiogram in chronic obstructive pulmonary disease patients”. Med Pregl. 66 (3–4): 126–9. PMID 23653989.
  3. Fargo MV, Grogan SP, Saguil A (2017). “Evaluation of Jaundice in Adults”. Am Fam Physician. 95 (3): 164–168. PMID 28145671.


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Epidemiology and Demographics

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Mazia Fatima, MBBS [2]

Overview

Alpha 1-antitrypsin deficiency (A1AD) is more common in people of Northern European, Iberian, and Saudi Arabian descent. Most researchers believe it is markedly underrecognized. The incidence of alpha 1-antitrypsin deficiency (A1AD) is estimated to be 20 cases per 100,000 individuals worldwide. The prevalence of alpha 1-antitrypsin deficiency AATD is estimated to be 70,000-100,000 cases annually. Alpha1-antitrypsin deficiency (AATD) is one of most common lethal genetic diseases among adult white population. Alpha1-antitrypsin deficiency AATD has estimated 117 million carriers and 3.4 million affected individuals. AATD is more prevalent among the white population. Alpha 1-antitrypsin deficiency (A1AD) is more common in people of Northern European, Iberian, and Saudi Arabian descent. Most researchers believe it is markedly under-recognized. Men and women are affected equally by AATD.

Epidemiology and Demographics

Epidemiology and demographic details of alpha 1-antitrypsin deficiency are as follows:[1][2][3]

In a recent survey, the average time interval between the onset of pulmonary symptoms and time of diagnosis was 7.2 years. About 43% of patients see at least 3 physicians before the diagnosis is established, and 12% see between 6 and 10. Thus, most authors believe that alpha-1 AT deficiency is markedly under-recognized. Because there are genetic implications to the next generation, that diagnosis can assist in smoking prevention / cessation.

Incidence

The incidence of AATD is estimated to be 20 cases per 100,000 individuals worldwide.

Prevalence

The prevalence of AATD is estimated to be 10,000 per 100,000 patients annually. Alpha1-antitrypsin deficiency (AATD) is one of most common lethal genetic diseases among adult white population. AATD has estimated 117 million carriers and 3.4 million affected individuals.

Race

AATD is more prevalent among the white population. Alpha 1-antitrypsin deficiency (A1AD) is more common in people of Northern European, Iberian, and Saudi Arabian descent. Most researchers believe it is markedly under-recognized.

Sex

Men and women are affected equally by AATD.

Age

References

  1. Stoller JK, Aboussouan LS (2012). “A review of α1-antitrypsin deficiency”. Am. J. Respir. Crit. Care Med. 185 (3): 246–59. doi:10.1164/rccm.201108-1428CI. PMID 21960536.
  2. Stoller JK, Brantly M (2013). “The challenge of detecting alpha-1 antitrypsin deficiency”. COPD. 10 Suppl 1: 26–34. doi:10.3109/15412555.2013.763782. PMID 23527684.
  3. Greene DN, Elliott-Jelf MC, Straseski JA, Grenache DG (2013). “Facilitating the laboratory diagnosis of α1-antitrypsin deficiency”. Am. J. Clin. Pathol. 139 (2): 184–91. doi:10.1309/AJCP6XBK8ULZXWFP. PMID 23355203.


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Risk Factors

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Mazia Fatima, MBBS [2]

Overview

First degree relatives of patients with known AAT deficiency are at an increased risk for the condition. Smoking is risk factor for development of serious lung disease in patients with AAT deficiency. Risk for lung disease also increases with exposure to dust, fumes, or other toxic substances.

Risk Factors

Risk factors associated with development of alpha 1-antitrypsin deficiency are as follows:[1][2]

References

  1. Kalfopoulos M, Wetmore K, ElMallah MK (2017). “Pathophysiology of Alpha-1 Antitrypsin Lung Disease”. Methods Mol. Biol. 1639: 9–19. doi:10.1007/978-1-4939-7163-3_2. PMID 28752442.
  2. Stoller JK, Aboussouan LS (2012). “A review of α1-antitrypsin deficiency”. Am. J. Respir. Crit. Care Med. 185 (3): 246–59. doi:10.1164/rccm.201108-1428CI. PMID 21960536.


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Screening

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Mazia Fatima, MBBS [2]

Overview

According to the Spanish Society of Pneumology and Thoracic Surgery (SEPAR), all COPD patients should be screened for AATD at least once in their lifetime. All patients with unexplained liver disease with or without respiratory symptoms should be evaluated for AATD.

Screening

Screening for alpha 1-antitrypsin deficiency includes:[1][2]

References

  1. Hersh CP (2017). “Diagnosing alpha-1 antitrypsin deficiency: the first step in precision medicine”. F1000Res. 6: 2049. doi:10.12688/f1000research.12399.1. PMC 5710307. PMID 29225784.
  2. Lascano JE, Campos MA (2017). “The important role of primary care providers in the detection of alpha-1 antitrypsin deficiency”. Postgrad Med. 129 (8): 889–895. doi:10.1080/00325481.2017.1381539. PMID 28929906.


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Natural History, Complications and Prognosis

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Mazia Fatima, MBBS [2]

Overview

If left untreated, not all patients with deficient gene develop symptomatic emphysema or cirrhosis. In symptomatic patients, the median time between observation of symptoms and diagnosis is approximately 8 years. The symptoms of alpha1-antitrypsin deficiency (AATD) in the first two decades of life are mainly of associated liver disease progressing to pulmonary manifestations appear later in life. Emphysema is seen in non-smokers in the fifth decade of life and during the fourth decade of life in smokers. Less common associations are panniculitis and cytoplasmic antineutrophil cytoplasmic antibody‒positive vasculitis. The most common cause of death is emphysema. Chronic liver disease is the second most common cause of death. Common complications of AATD include pneumothorax, pneumonia, acute exacerbation of airflow obstruction, respiratory failure. Prognosis depends on how patients are identified. Patients identified as a result of screening often have excellent prognosis. Those identified because of their symptoms have poor prognosis.

Natural History

Complications

Common complications of AATD include:[3]

Prognosis

Prognosis depends on how patients are identified. Patients identified as a result of screening often have excellent prognosis. Those identified because of their symptoms have poor prognosis.[1][2][3]

Features associated with poor prognosis include:

References

  1. 1.0 1.1 Brantly ML, Paul LD, Miller BH, Falk RT, Wu M, Crystal RG (1988). “Clinical features and history of the destructive lung disease associated with alpha-1-antitrypsin deficiency of adults with pulmonary symptoms”. Am. Rev. Respir. Dis. 138 (2): 327–36. doi:10.1164/ajrccm/138.2.327. PMID 3264124.
  2. 2.0 2.1 “Survival and FEV1 decline in individuals with severe deficiency of alpha1-antitrypsin. The Alpha-1-Antitrypsin Deficiency Registry Study Group”. Am. J. Respir. Crit. Care Med. 158 (1): 49–59. 1998. doi:10.1164/ajrccm.158.1.9712017. PMID 9655706.
  3. 3.0 3.1 3.2 Stoller JK, Tomashefski J, Crystal RG, Arroliga A, Strange C, Killian DN, Schluchter MD, Wiedemann HP (2005). “Mortality in individuals with severe deficiency of alpha1-antitrypsin: findings from the National Heart, Lung, and Blood Institute Registry”. Chest. 127 (4): 1196–204. doi:10.1378/chest.127.4.1196. PMID 15821195.


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Diagnosis

Diagnosis

History and Symptoms | Physical Examination | Laboratory Findings | Electrocardiogram | X Ray | CT | MRI | Echocardiography or Ultrasound | Other Imaging Findings | Other Diagnostic Studies

Treatment

Treatment

Medical Therapy | Surgery | Primary Prevention | Secondary Prevention | Cost-Effectiveness of Therapy | Future or Investigational Therapies

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Template:Endocrine, nutritional and metabolic pathology


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