Clinical features and natural history of severe alpha 1-antitrypsin deficiency. Roger S. Mitchell Lecture.
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Extensive research, stimulated by the recognition of an association between alpha 1-antitrypsin (alpha 1-AT) deficiency and emphysema, has greatly advanced our understanding of emphysema in general. In this article, we review the literature concerning the basic defect, inheritance, pathogenesis of lung disease, clinical, physiologic, and roentgenographic findings in patients with severe (Pi SZ) deficiency of alpha 1-AT. Data obtained in relatives with alpha 1-AT deficiency, who have not been seen by a physician, should more truly reflect the risk of having lung disease. These studies confirm the increased risk of developing lung disease in cigarette smokers. The implications of the finding that subjects with Pi SZ are probably not at an increased risk of lung disease is discussed with regards to replacement therapy. The natural history of unselected subjects with alpha 1-AT deficiency remains unknown.
By light microscopy and immunoperoxidase methods, morphology and distribution of alpha-1-proteinase inhibitor (Api) cells in the pancreatic islets were studied in seven patients with and in 17 patients without periodic acid-Schiff-positive, diastase-resistant globules in the liver. Five of the seven patients with liver globules had cirrhosis and emphysema, suggesting genetic deficiency of Api, which was confirmed in four by pi phenotyping (blood from one patient was not available). The two remaining patients had only a mild degree of liver fibrosis and mild emphysema and showed a normal MM phenotype. Islet cell hyperplasia and an increased population of Api cells were observed in all five patients with genetic deficiency, compared with the 17 patients without Api deficiency. These morphologic changes were more pronounced in the one homozygous patient than in the heterozygous patients. Nesidioblastosis, ductular proliferation, and atypia of insular cells were seen only in patients with an abnormal phenotype. The increased amount of Api in the islets in the genetic deficiency state may be due to hyperplasia and hypertrophy of Api cells or due to storage of abnormal Api in the preexisting Api cells. The exact stimulus for islet cell hyperplasia and proliferation of Api cells is still unknown.
The homozygous mutant klotho (KL-/-) mouse, which is deficient in klotho gene expression, exhibits multiple phenotypes resembling human aging that include a short life span, arteriosclerosis, osteoporosis, skin atrophy, and ectopic calcifications. Histologic examination of KL-/- mice at 4 weeks of age reveals pulmonary emphysema. The emphysematous changes are not caused by a developmental defect or hypoplasia of the lung. The lungs of heterozygous mutant klotho (KL+/-) mice show emphysematous changes and alveolar calcification which are almost identical to those in KL-/- mice. These observations indicate that the klotho gene expression is essential to maintaining normal alveolar architecture in postnatal life. Pulmonary function tests reveal prolonged expiration time in KL-/- mice. The expression of type IV collagen and surfactant protein-A mRNA is markedly upregulated in KL-/- mice, suggesting that a defect in matrix synthesis or in type II pneumocyte function, or both, may be involved in the pathogenesis of pulmonary emphysema in this mutant. Several animal strains have been reported to develop pulmonary emphysema, but the klotho mouse is unique because it simultaneously exhibits various aging phenotypes. Analysis of pulmonary emphysema in klotho mice will provide a unique insight into the relationship between pulmonary emphysema and aging.
BACKGROUND AND METHODS: Single lung transplantation for emphysema is now standard practice despite initial concerns, including the possibility that the compliant diseased lung would compress the transplanted lung as a result of hyperinflation. We describe a patient with severe bilateral bullous emphysema and alpha-1-antitrypsin deficiency who underwent single lung transplantation after which hyperinflation of the native lung led to significant compression of the pulmonary allograft. The patient subsequently underwent bullectomy of the contralateral lung with marked improvement in his functional status. RESULTS: After bullectomy, the patient's forced expiratory volume in 1 second increased from 1.77 to 2.82 L, his total lung capacity fell from 7.23 to 6.19 L, and his 6-minute walk increased from 724 to 1269 feet. However, 7 months after bullectomy, there was evidence that the bullous disease in the native lung was recurring. CONCLUSIONS: Significant hyperinflation of the native lung with compromise of the pulmonary allograft can occur after single lung transplantation for bullous emphysema. Bullectomy of the diseased lung after transplantation improved allograft function in our patient. Alternatively, bilateral lung transplantation for severe bilateral bullous emphysema may be considered.
Alpha-1-antitrypsin (alpha 1AT) deficiency is a hereditary disorder characterized in adults by a high risk for the development of severe destructive lung disease at an early age. The present study was designed to draw conclusions concerning the characteristics of a referral population of 124 patients with alpha 1AT deficiency and symptomatic emphysema. Typically, the alpha 1AT level was 30 mg/dl, and the alpha 1AT phenotype was almost always PiZZ. The individuals in this population were most often male, caucasian, and ex-smokers, and they had become dyspneic between 25 and 40 yr of age. Most routine blood tests were normal. The chest radiographs and ventilation-perfusion studies typically showed abnormalities with a lower zone distribution, and about one third of the study population had evidence suggestive of pulmonary hypertension. Lung function tests were typical for emphysema; the FEV1 and DLCO were the parameters most dramatically reduced, and the annual rate of decline of those parameters was greater than that of the general population. The cumulative probability of survival of this population indicated a significantly shortened lifespan with a mean survival of 16% at 60 yr of age compared with 85% for normal persons.
A 49-year-old woman was found to have emphysema associated with alpha 1-antitrypsin deficiency in February 1975. She was followed until her death in October, 1994. The Pi phenotype was M null and the genotype was M malton. She had been on home oxygen therapy since 1987. An autopsy revealed the typical bullous lungs with panacinar emphysema. We know of no previous case in Japan of emphysema associated with alpha 1-antitrypsin deficiency.
Of 72 patients with radiological evidence of pulmonary emphysema, emphysema occurred either alone or in association with bronchitis in 61, and 8 of these (13%) were found to have alpha(1)-antitrypsin deficiency. The main features of this condition are: exertional dyspnoea of relatively early onset (generally between 30 and 45 years of age), severely impaired FEV(1) and T(L)CO, and radiological emphysema predominantly affecting the lower zones of the lungs. It is probable that any patient with all the above abnormalities has alpha(1)-antitrypsin deficiency. There is evidence to suggest that cigarette smoking may hasten the onset of this type of emphysema.
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A survey of alpha1-antitrypsin phenotypes and serum trypsin inhibitory capacities was performed in 1,841 seventh grade junior high school students. Antitrypsin deficiency states were detected only in white subjects (3.04) per cent) and not in 461 subjects of other races or of Mexican origin. A screening level of serum trypsin inhibitory capacity at 75 per cent of normal or less included all of the deficient phenotypes, but phenotyping was necessary to eliminate a small percentage of normal and unimportant variant phenotypes from this group. It is suggested that future programs for detecting antitrypsin deficiency and for counseling students who are genetically prone to develop pulmonary emphysema be aimed primarily at white populations.
Alpha1-antitrypsin (alpha1-AT) is a serum protease inhibitor with a well established role in bodily defense against destructive inflammatory diseases. alpha1-AT exhibits inheritable genetic polymorphism (Pi types). Certain Pi types have been shown to predispose to emphysema and, in this study, also appear to be related to increased chronic periodontitis susceptibility.
Patients afflicted with emphysema demonstrate altered peripheral skeletal muscle fibre composition and atrophy. It is unknown whether these alterations are general to all skeletal muscles independent of function, phenotype or oxidative capacity. Therefore, the purpose of this investigation was to determine whether emphysema induces alterations in muscle fibre composition or atrophy in respiratory and locomotory muscles with diverse fibre types and metabolic profiles. Fibre composition and cross-sectional area were measured in selected hindlimb muscles and diaphragm of hamsters following saline (control, n=7) or elastase (emphysema, n=15) instillation. Excised lung volume increased 145% with emphysema. Fibre composition was largely unaltered, with the exception of a 13% reduction in IIB fibres in the tibialis anterior muscle of emphysema animals. Type I fibre size was also mainly unaltered, except for a diminished cross-sectional area in plantaris muscle. However, fibre cross-sectional area of fast-twitch types IIA, IIX and/or IIB fibres was reduced in the caudal biceps femoris, vastus lateralis, tibialis anterior, gastrocnemius and plantaris muscles of emphysema animals. In contrast, there was a trend for emphysema to increase the cross-sectional area of type IIA fibres in the diaphragm. These data demonstrate that emphysema-induced atrophy primarily affects locomotory muscles, independent of phenotype or oxidative capacity.
The chest radiographs and computed tomographic (CT) scans of seven patients with homozygous proteinase inhibitor phenotype Z (PiZZ) alpha 1-antitrypsin deficiency were reviewed. All patients except one showed severe emphysema with or without bullous change. Bronchiectasis was detected in three patients by CT but only in two patients by chest radiography. A young patient developed bronchiectasis before symptomatic emphysema. We stress that patients with PiZZ are susceptible to bronchiectasis, and the widespread use of CT should reveal its true incidence which might not be as low as generally believed.
Alpha-1-antitrypsin deficiency (AAT deficiency) is one of the most common serious hereditary disorders in the world, as its affects all major racial subgroups worldwide, and there are an estimated 120.5 million carriers and deficient subjects worldwide. This genetic disease is related to susceptibility for development of jaundice in infants, liver disease in children and adults and pulmonary emphysema in adults. Moreover, AAT deficiency carrier phenotypes (PiMS and PiMZ) and deficiency allele phenotypes (PiSS, PiSZ and PiZZ) are suspected to predispose subjects to a variety of other adverse health effects. Because there is a limited database on the number of individuals affected by this disease worldwide, we have collected data on control cohorts in genetic epidemiological studies published on case-control studies in the peer-reviewed literature worldwide. Based on these data, we estimated the numbers of carriers and deficiency allele combinations for the two most common defective alleles, namely PiS and PiZ in 58 countries worldwide. The present paper focuses on the distribution of the PiS and PiZ deficiency alleles in Australia, Canada, New Zealand and the United States of America. A total of 31,042,232 individuals at risk for adverse health effects have been calculated in these four countries: 2,144,158 in Australia, 3,258,564 in Canada, 430,922 in New Zealand and 24,909,548 in the United States of America. The prevalences for all five phenotypic classes of AAT deficiency in each of these countries is as follows: Australia 1 out of 8.9, Canada 1 out of 9.8, New Zealand 1 out of 8.5 and the United States of America 1 out of 11.3. The geographical distribution of individual control cohorts and estimates of the numbers of carriers and deficiency allele phenotypes in each of these four countries are given in individual tables.