[Homozygous alpha 1-antitrypsin deficiency. Lung changes in children and adolescents]

Homozygous alpha 1-antitrypsin deficiency can lead to pan-lobular emphysema early in adulthood. Based on own studies and a review of the literature the article dates up the knowledge about risk factors (especially smoking), the variable clinical pattern (relationship to bronchial hyperreactivity) and pulmonary function (30% pulmonary hyperinflation) of children and adolescents with homozygous alpha 1-antitrypsin deficiency (PIZZ). It discusses diagnostic (selective screening, regular lung function tests) and therapeutic possibilities (substitution) as well as preventive aspects (passive and active smoking cessation).

Allelic frequency of a p53 polymorphism in human lung cancer

p53 is a tumor suppressor gene that is mutated in diverse tumor types. Here we report the frequencies of common polymorphic variants at codon 72 of the p53 gene in germline DNA of lung cancer cases and controls as determined by a polymerase chain reaction strategy. The observed allelic distribution was found to be significantly different between African-Americans and Caucasians in this U.S. population. The frequency of polymorphic variants was similar in lung cancer cases and controls after adjustment for race. However, among lung cancer patients the proline variant at codon 72 was in excess in adenocarcinoma patients by comparison with other histologies.

Improved phenotyping of alpha 1-antichymotrypsin (ACT) by isoelectric focusing and immunoprinting: first demonstration of a deficient protein variant in the ACT system

Genetic variation of human alpha 1-antichymotrypsin (ACT) was investigated in sera using thin-layer polyacrylamide gel isoelectric focusing (pH range 4.0-6.5) followed by immunoprinting with a monospecific anti-human ACT antibody. Sialidase-treated samples showed a microheterogeneous banding pattern which consisted of two major and several additional minor components with isoelectric points between pH 5.0 and 5.3. A population study of 200 unrelated individuals from southern Germany revealed no genetic variation. In a clinical investigation, however, we found a unique banding pattern in a female patient suffering from chronic obstructive pulmonary disease. In comparison with the monomorphic normal type the detected variant phenotype shows two additional bands that have lower intensities and are located cathodically to their major bands. Inheritance of the deficient IEF variant "ACT Bochum" was confirmed by a family study. To our knowledge this is the first genetic ACT mutant to be observed at the protein level.

The characterization of a mutation of the 3' flanking sequence of the alpha 1-antitrypsin gene commonly associated with chronic obstructive airways disease

A restriction fragment length polymorphism (RFLP) of the 3' flanking region of the alpha 1-antitrypsin (AAT) gene, detected with the restriction enzyme TaqI, occurs in about 17% of patients with chronic obstructive airways disease (COAD). To characterize the mutation the sequence of this region of the normal AAT gene had to be determined. The sequence containing the site of the mutation was amplified by the polymerase chain reaction and the DNA was sequenced in six COAD patients. The mutation is a G to A transition and occurs in a region containing potential regulatory sequences corresponding to enhancer elements. It is as yet unclear if the mutation alters the expression of AAT.

Effects of passive smoking on lung growth in children

The objective of this study was to determine the effects of passive smoking on functional lung growth in children and adolescents. It was hypothesized that passive smoking might reduce lung function growth, especially in susceptible children. The assumption was that those most susceptible would be children who started with low lung function, as it had been shown that they had slower growth of lung function, and start to decline earlier. There were 138 non-Hispanic Caucasian children and adolescents, ages 5 through 15, who had at least three satisfactory longitudinal lung function tests over a 13 year period in the Tucson epidemiological study of airway obstructive diseases. Those who started in childhood with normal function did not show any effect of passive smoking, nor did females who started with low lung function. Males starting with low lung function whose parents smoked showed definite changes. Their forced expiratory volume in 1 second (FEV1) grew even more slowly between ages 13 through 16, related primarily to continuous parental smoking. They also had higher rates of decline for FEV1 to forced vital capacity (FVC) ratio and maximum flow at 50% vital capacity to FVC ratios than either the low function group without passive smoking or the normal function groups. This was independent of any symptoms or diagnoses present in this male low function group.

Three cases of alpha 1-antitrypsin deficiency: a review of diagnostic and therapeutic strategies

Deficiency of alpha 1-antitrypsin is an unusual cause of emphysema. This deficiency may be suspected when the age of onset and severity of disease are out of proportion to the history of inhaled agents (usually cigarette exposure). Three patients seen during a relatively short time in a private practice underscore the variability of presentation. Proper diagnosis offers such patients several benefits, particularly in view of new potential therapies.

Family study of alpha 1-antitrypsin deficiency: effects of cigarette smoking, measured genotype, and their interaction on pulmonary function and biochemical traits

To gain insight into the variable expression of lung disease in alpha 1-antitrypsin (alpha 1AT) deficiency, five quantitative variables including forced expiratory volume at 1 sec (FEV1), forced expiratory flow rate between 25 and 75% of forced vital capacity (FEF25-75), total serum alpha 1AT, oxidized serum alpha 1AT, and total serum immunoglobulin E (IgE) were measured in alpha 1AT deficient individuals and their families. The effect of a known, measured genotype (the Pi type) was estimated for each quantitative trait; the influence of mode of case ascertainment on the measured genotype effect was also assessed. These analyses showed that total alpha 1AT levels are strongly influenced by Pi type; IgE levels are unaffected by Pi type; and FEV1, FEF25-75, and oxidized alpha 1AT are moderately influenced by Pi type. The effect of genotype-by-environment interaction between Pi type and pack-years of cigarette smoking on the five quantitative phenotypes was studied using an analysis of covariance. Significant Pi x pack-years interaction was evident for FEV1, but this effect is confounded in this data set with the Pi x age interaction. Probands who were ascertained because they had chronic obstructive pulmonary disease (COPD) do not demonstrate the significant Pi x pack-years interaction effect of the Pi x pack-years subjects ascertained for other reasons demonstrate. The effect of the Pi x pack-years interaction on FEV1 was no longer significant on a transformed scale, (FEVf12,) thus providing an additive scale for future data analysis. The increased sensitivity of Pi MZ individuals in our sample to cigarette smoking reduced the Pi x packs-years interaction effect on FEF25-75 to borderline significance. This investigation has provided an opportunity to incorporate both measured genotype and genotype-by-environment interaction analyses into the study of the variable expression of lung disease in Pi Z individuals.

Cloning of the human ?2-macroglobulin gene and detection of mutations in two functional domains: the bait region and the thiolester site

Overlapping genomic clones of the human alpha 2-macroglobulin (alpha 2M) gene were isolated from a cosmid library and were used to map 80 kb of the chromosomal region of this gene. Fragments carrying the two exons encoding the bait region and the exon encoding the thiolester site were partially sequenced and PCR primers were designed for the amplification of both functional domains. By direct genomic sequencing of these domains in 30 healthy individuals and in 30 patients with chronic lung disease three mutations were detected. The first was a sequence polymorphism occurring near the thiolester site of the gene, changing Val1000 (GTC) to Ile1000 (ATC), with allele frequencies of 0.30 (GTC) and 0.70 (ATC), respectively. No difference of alpha 2M serum levels was observed for these two alleles. The second mutation occurred within the thiolester site of one patient, changing Cys972(TGT) to Tyr972(TAT). Since activation of the internal thiolester formed between Cys972 and Gln975 in each of the subunits of the tetrameric alpha 2M is involved in the covalent cross-linking of the activating proteinase, this mutation is predicted to interfere with alpha 2M function. The alpha 2M serum level was within the normal range in this patient. In one healthy individual we detected an alteration of the bait region sequence, which is usually encoded by two different exons separated by an intron of size 1.6 kb. In this individual, PCR amplification of genomic DNA using the bait region primers produced the common fragment of size 1.8 kb and an additional variant fragment of size 0.23 kb. This finding, and the genomic sequencing data of this individual, indicate that he carries two different alleles of the alpha 2M gene: one with the regular structure (bait exon I-intron-bait exon II), the other with the two bait exons fused into one. Direct genomic sequencing of the two alpha 2M functional domains is a useful tool for the detection of the genetic, and possibly the functional, heterogeneity of alpha 2M. This, in turn, may provide some insight into the hitherto unknown physiological role(s) of alpha 2M, by studying in vivo effects of naturally occurring mutations of the gene.

Sequence analysis of the cystic fibrosis gene in patients with disseminated bronchiectatic lung disease. Application in the identification of a cystic fibrosis patient with atypical clinical course

The diagnosis of classical cystic fibrosis (CF) is easily made by clinical assessment alone, but may be missed or delayed in cases with an atypical clinical course. In a recent major study the age at diagnosis varied between 2 months and 47 years. For diagnostic purposes we have investigated the cystic fibrosis transmembrane regulator (CFTR) gene in 10 adult patients (age 18 to 45 years) with chronic obstructive pulmonary disease since childhood or adolescence and bronchiectases disseminated through both lungs. Only one subject (a 29-year-old male) had exocrine pancreatic insufficiency (PI); all others were pancreatic-sufficient (PS). The first nucleotide (ATP)-binding fold of the CFTR was analyzed by direct sequencing of polymerase chain reaction (PCR)-amplified genomic DNA in these cases. Two patients with different phenotypes (one PI, one PS) were found to be homozygous for the common delta F508 mutation of the CFTR gene, which proved the diagnosis of cystic fibrosis in their cases and allowed genetic counselling. The PS patient had normal sweat tests and had not previously been recognized as having CF. Four other patients were heterozygous for delta F508, with no other mutation in exons 10 or 11 of the gene, and four patients had normal sequences of these exons. Because only about 70% of all CF chromosomes carry delta F508, the unexpectedly high frequency (4/8 = 50%) of heterozygosity for delta F508 among the non-delta F508/delta F508 patients with bronchiectases suggests that some of these might also have unrecognized CF with rare genotypes and mutations in any of the 22 exons not sequenced.(ABSTRACT TRUNCATED AT 250 WORDS)

Longitudinal analyses of respiratory chemosensitivity in normal subjects

To evaluate relative contributions of inherent versus extrinsic factors to respiratory chemosensitivity, ventilatory responses to isocapnic progressive hypoxia and normoxic progressive hypercapnia were examined at intervals of 8 to 10 yr in 32 healthy male volunteers aged 42.2 +/- 1.4 yr (SEM) in the final examination. The volunteers included 22 sons of patients with chronic obstructive pulmonary disease. The mean value for the slope factor of the end-tidal PO2-ventilation hyperbola (A) significantly decreased from 98.3 +/- 12.2 to 77.4 +/- 10.3 L/min mm Hg (p less than 0.05), but that for the end-tidal PCO2 ventilation line (S) did not change over the years. The individual values for the hypoxic ventilatory response were significantly correlated (r = 0.63, p less than 0.001) between the initial and final examinations but not so for the hypercapnic ventilatory response (r = 0.23, NS), suggesting that the latter is more subject to influence from extrinsic factors than the former in the long term. The reproducibility of both tests expressed as coefficients of variation was similar or rather small for the hypercapnic ventilatory response, which was determined by three consecutive measurements at 1 wk intervals in a different group of six subjects. From these data we conclude that hypoxic chemosensitivity is more determined by factors inherent to the individual than hypercapnic chemosensitivity and that it is more systematically influenced by temporal factors, as demonstrated by the systematic decrease over the years.

A "splitting" look at chronic nonspecific lung disease (CNSLD): common features but diverse pathogenesis

The term chronic nonspecific lung disease (CNSLD) was proposed by the Ciba Symposium in 1959 as an umbrella term grouping chronic bronchitis, asthma, emphysema and irreversible or persistent obstructive lung disease. However, it has only been widely used by proponents of the Dutch Hypothesis, which states that these diseases all result from a common genetic root and should be considered as one disease. A major reason for proposing this hypothesis in 1961 was that these different entities share some common features, especially airway hyperresponsiveness. Although not formally disproven, evidence is accumulating--and reviewed here--against this "one disease concept"; hence, common features should not necessarily imply a common pathogenesis. Overlap features are sufficiently frequent in clinical practice to cause problems for labelling patients within the scope of CNSLD. The term could still be used as a starting point for a "splitting approach", identifying a small number of important basic features in order to allow a more systematic use of established labels for diseases within CNSLD. Our proposal for labelling emphasizes a consistent use of asthma, emphysema and chronic obstructive pulmonary disease (COPD), but restricts the use of chronic bronchitis to those patients with chronic bronchial hypersecretion without chronic airways obstruction.

[Analysis of dysanapsis in healthy twins and sons of patients with chronic obstructive lung disease]

Pulmonary function tests and tracheal cross-sectional area (X-SA) measured on chest roentgenograms were analyzed in 72 healthy pairs of twins and in 34 healthy sons of patients with chronic obstructive lung disease. In the twin study, genetic influence was positive on most pulmonary function tests, including VC, FEV1/FVC, V25, but not so on X-SA. The ratio of X-SA to VC, which represents dysanapsis, had no relation to sex nor height. However, the ratio of X-SA/VC showed marked sex-associated differences, when expressed as a function of VC, and had a negative correlation with VC both in men and women. The ratio of X-SA/VC was significantly lower in sons of patients with COPD than in normal controls, which was caused by significantly larger VC in the former group. The relatively low ratio of tracheal size to lung size may partly explain the susceptibility to the possible future development of COPD in those subjects.

Alpha 1-antitrypsin deficiency--diagnosis, treatment, and control: identification of patients

Severe alpha 1-antitrypsin (AAT) deficiency is a relatively common inherited condition in populations of Northern European heritage. Current estimates of the prevalence of the PiZ phenotype range between 1/3500 and 1/1670 in the United States. Clues to the whereabouts of the undiagnosed individuals with severe hereditary AAT deficiency can come from the existing information about the natural history and clinical course of disease. In the PiZ smoker, dyspnea develops soon after age 30 years or at least before age 40, and death from emphysema is likely by age 50. The PiZ nonsmoker has a prognosis only marginally worse than that of the susceptible smoker without AAT deficiency. Dyspnea often does not appear until after age 50 years, and clinically significant emphysema not usually until after age 60. All infants presenting with liver disease in the neonatal period should be tested for the deficiency. In adults, clinically significant dyspnea in the 30s and 40s, in association with abnormal lung function, should raise the suspicion of AAT deficiency. In nonsmokers, dyspnea at any age justifies further investigation. A serum AAT level below 80 mg/dl (11 microM) is considered abnormal; individuals falling in this range should be phenotyped. The formation of a Registry for severe hereditary AAT deficiency in the United States, under the auspices of the National Heart, Lung and Blood Institute of the NIH, is also described.

A family study of the variability of pulmonary function in alpha 1-antitrypsin deficiency. Quantitative phenotypes

A group of 52 alpha 1-antitrypsin-deficient individuals of phenotype Pi Z and 117 of their relatives underwent a protocol including pulmonary function testing, completion of a questionnaire, and blood donation. Our population permitted a minimum frequency estimate (7 x 10(-4)) for Pi null alleles. Five quantitative phenotypes were measured, including FEV1, FEF25-75, total serum alpha 1AT, oxidized serum alpha 1AT, and total serum IgE. We found that (1) total alpha 1AT levels were higher in Pi Z subjects with lung function impairment (FEV1 less than or equal to 65% of predicted) than in Pi Z subjects who were not impaired; (2) Pi Z subjects with lung function impairment had elevated serum levels of oxidized alpha 1AT; and (3) IgE levels were relatively elevated in first-degree Pi MZ relatives of impaired Pi Z subjects. Moreover, FEV1 tended to be relatively reduced in heterozygous parents of impaired Pi Z subjects, suggesting that a subset of Pi MZ individuals are at risk for development of lung disease because of familial factors. These results represent an initial step toward the development of intermediate phenotypes that will be predictive of a severe course in alpha 1AT deficiency; they suggest that, in addition to cigarette smoking, atopic predisposition and undetermined familial factors may be important codeterminants of lung disease progression.

Highly variable clinical course in severe alpha 1-antitrypsin deficiency--use of polymerase chain reaction for the detection of rare deficiency alleles

Among 20 individuals with severe alpha 1-antitrypsin (alpha 1AT) deficiency we observed extremely variable clinical phenotypes ranging from rapidly progressive lung disease fatal at the age of 42 years to an asymptomatic individual with normal lung function at the age of 50 years. Eighteen subjects, including the asymptomatic one, carried the deficient Pi ZZ phenotype as determined by isoelectric focusing (IEF). Their mean alpha 1AT serum level was 36.7 +/- 7.7 mg/dl. DNA restriction analysis showed that all of them had the classical Pi Z-allele-associated DNA haplotype, thus confirming the IEF data. Obviously not all Pi ZZ individuals will have clinical sequelae caused by this genotype. The important differences in clinical course observed could not be explained by smoking habits alone. Probably additional factors are pertinent to the pathogenesis of the lung disease associated with alpha 1AT deficiency (defects in other genes, environmental influences other than smoking). In two patients with very low alpha 1AT serum levels definitive phenotyping by IEF was not possible. Therefore we investigated the molecular basis of their deficiency using polymerase chain reaction (PCR) amplification of the coding exons of their alpha 1AT genes and direct sequencing of the amplification products. Sequence data analysis showed that one of these patients, who had initially been phenotyped as Pi ZZ by IEF, had in fact the genotype Pi QObellinghamZ, thus explaining her low alpha 1AT serum level of 20 mg/dl. The other patient (alpha 1AT serum level 3.7 mg/dl) exhibited the rare genotype Pi MheerlenQOgranite falls. Despite his nearly complete alpha 1AT deficiency, he suffered from only moderately severe pulmonary disease at the age of 42 years.

Lung cancer and the debrisoquine metabolic phenotype

In a case-control study, we tested the hypothesis that the genetically determined ability to metabolize debrisoquine is related to risk of lung cancer. Overall, individuals who were extensive metabolizers of debrisoquine were at significantly greater risk of lung cancer than those who were poor or intermediate metabolizers (odds ratio = 6.1; 95% confidence interval = 2.2-17.1). In this study, case patients had lung cancer, and control subjects had either chronic obstructive pulmonary disease or cancers other than lung cancer. Results were adjusted for age, race, asbestos exposure, and smoking. Both black and white individuals who were extensive metabolizers of debrisoquine were at significantly increased risk after similar adjustment (for blacks, odds ratio = 4.5, 95% confidence interval = 1.1-18.1; for whites, odds ratio = 10.2, 95% confidence interval = 2.0-51.4). Significantly increased risk of lung cancer was also present for individuals who were extensive metabolizers when subjects with chronic obstructive pulmonary disease or other cancers were considered separately. These data confirm that the ability to metabolize debrisoquine is a major determinant of susceptibility to lung cancer. Evaluation of the marker in other case-control settings, further exploration of racial differences, and the prospective evaluation of this marker in subgroups at high risk of lung cancer are areas worthy of further study.

The cystic fibrosis gene is not likely to be involved in chronic obstructive pulmonary disease

The etiology of chronic obstructive pulmonary disease (COPD) is still unknown, and both genetic and environmental factors may play a role. Some clinical aspects of COPD occur similarly in cystic fibrosis (CF), particularly in adult patients. A DNA polymorphic marker in strong linkage disequilibrium with the CF locus has been used to check the hypothesis that mutations of this locus might be involved in COPD. Its allele frequencies have been found to be in equilibrium in COPD patients as well as in appropriate control subjects. The determinants possibly involved in genetic predisposition to COPD therefore do not seem to comprise CF gene mutations.

[Idiopathic lung fibrosis]

In a 39-year-old patient with chronic progressive idiopathic pulmonary fibrosis, the genetic aspects, course and therapeutic possibilities of the disease are discussed. In February, 1987, the English-born patient, Anthony V., attended for initial examination on account of progressive dyspnoea, on which occasion radiology and pulmonary function analysis revealed advanced pulmonary fibrosis. The patient's family history revealed a familial genesis, since both his father (?) and his sister had died of this disease. A comparative of the patient's chest films with original chest films of his sister revealed almost identical findings. Within the previous twelve months, follow-up examinations done on A.V. revealed an increase in the restrictive component (reduction of vital capacity from 2,400 ml to 1,500 ml), development of partial respiratory failure at rest, and global respiratory failure in response to mild ergometric exercise despite intermittent high-dose steroid administrations superimposed on long-term, low-dose steroid therapy. The unfavourable evolution observed over the past 12 months is underscored by an increase in mean pulmonary arterial pressure from 18 mmHg initially to a present 34 mmHg at rest, and 46 mmHg under submaximal ergometric loading. The only option still left to the patient is the possibility of a lung transplantation, which - probably initially unilateral - is scheduled to be carried out in the near future at the Chest Surgery Department of the Medical University at Hannover.

DNA polymorphisms of the alpha 1-antitrypsin gene region in patients with chronic obstructive pulmonary disease

Alpha 1-antitrypsin (AAT) is an important part of the defence mechanism of the lung against proteolytic attack. The Z and Null mutants of the AAT gene are associated with very low or missing serum concentrations of AAT, so that for individuals with genotypes ZZ or Null there is a very high risk of developing chronic obstructive pulmonary disease (COPD). In more than 90% of the patients suffering from COPD, however, the common MM phenotype of AAT is expressed at normal AAT serum levels. The MM phenotype has a heterogeneous constitution and the alleles M1, M2 and M3 are distinguished by isoelectric focusing. At the DNA level many mutants of the AAT gene may exist that cannot be recognized by IEF. In this paper we report DNA sequence heterogeneity of the AAT gene region among 137 patients with COPD and 130 healthy control subjects. All 267 individuals studied were MM phenotype. Several restriction fragment length polymorphisms (RFLPs) were observed using genomic probes of the AAT gene. One allele (T2) of a Taq I RFLP located 1 kb downstream of the AAT gene was significantly more frequent in patients (15.3%) than in controls (5.4%) (P less than 0.005). The relative incidence of COPD was 3.3 times higher for subjects carrying at least one T2 allele than for the common T1T1 genotype. The T2 allele may be in linkage disequilibrium with a functionally deficient variant of AAT or some gene in close neighbourhood, e.g. the alpha 1-antichymotrypsin gene. A deletion of 1.8 kb in the alpha 1-antichymotrypsin-like gene (PIL gene) occurs at a frequency of 0.26 in patients and in control subjects as well.

[Clinical aspects, diagnostic lung function and biochemical parameters in children with homozygous alpha 1-antitrypsin deficiency]

Both the clinical course of the homozygous alpha 1-PI deficiency and also the pulmonary function and measured clinical parameters in these children revealed very marked inter-individual fluctuations. In one child, the lung function revealed certain signs of incipient pulmonary emphysema. The biochemical parameters of two children revealed TIC/alpha 1-PI- and PEIC/alpha 1-PI ratios greater than 1. This indicates that, in addition to alpha 1-PI, further inhibitors may develop a compensatory effect.