[The current state of substitution treatment in congenital emphysema due to alpha-1-antitrypsin deficiency. The report of the National Registry]

[Respiratory disease registries in Spain: fundamentals and organization]

This present paper describes the general characteristics, objectives and organizational aspects of the respiratory disease registries in Spain with the aim to report their activities and increase their diffusion. The document compiles information on the following registries: the Spanish Registry of Patients with Alpha-1 Antitrypsin Deficiency, Spanish Registry of Bronchiectasis, International Registry of Thromboembolic Disease, Spanish Registry of Occupational Diseases, Spanish Registry of Pulmonary Artery Hypertension, Registry of Pleural Mesothelioma, Spanish Registry of Tuberculosis and Spanish Multi-center Study of Neuroendocrine Pulmonary Tumors. Our paper provides information on each of the registries cited. Each registry has compiled specific clinical information providing data in real situations, and completes the results obtained from clinical assays. Said information has been published both in national as well as international publications and has lead to the creation of various guidelines. Therefore, the activities of the professionals involved in the registries have spread the knowledge about the diseases studied, promoting the exchange of information among workgroups.

Augmentation therapy for emphysema due to alpha-1-antitrypsin deficiency

Alpha-1 antitrypsin deficiency (AAT) is a hereditary recessive autosomal disease caused by mutations in the AAT gene. This disease is characterized by abnormally low AAT concentrations in plasma, which, in its homozygote form, carries a high risk for the development of early pulmonary emphysema and liver damage. Since the end of the 1980s augmentation therapy with AAT from human plasma has been available for specific treatment of emphysema due to AAT deficiency. Intravenous augmentation therapy has been demonstrated to be safe and weekly infusions of AAT have resulted in plasma AAT concentrations above those considered protective for the lungs. However, life-long weekly infusions are not well accepted by patients, therefore pharmacokinetic studies have been performed to try to individualize the therapeutic regimen in order to obtain adequate trough serum AAT levels with prolonged intervals of administration. Therapeutic regimens administered every two weeks appear to be safe and result in adequate trough serum concentrations, but less-frequent administrations result in trough levels below the target. Alpha-1-antitrypsin deficiency is largely unrecognized and underdiagnosed. The foundation of national and international registries is a valid strategy to increase awareness about the disease and collect information about the natural history of this deficiency. Furthermore, the identification of a large number of patients will allow the development of new clinical trials aimed at finding better treatments for this infrequent condition.

[Alpha1-antitrypsin deficiency: situation in Spain and development of a screening program]

Studies undertaken in Spain indicate that 9% of the general population aged between 40 and 70 years is affected by chronic obstructive pulmonary disease (COPD). Although tobacco smoke is the causative factor in more than 90% of cases, it is estimated that only 10% to 20% of smokers develop COPD. This may be explained by the existence of genetic or environmental factors that modulate the toxic effects of tobacco. The best known genetic factor is alpha1-antitrypsin deficiency, which is associated with an increased risk of developing pulmonary emphysema in smokers. The most recent guidelines from both the World Health Organization and the American Thoracic Society/European Respiratory Society recommend the establishment of screening programs for the detection of alpha1-antitrypsin deficiency in patients with COPD. This strategy is crucial in Spain, where the disease is under diagnosed, mainly due to a low index of suspicion among doctors.

[PI*S and PI*Z alpha 1-antitrypsin deficiency: estimated prevalence and number of deficient subjects in Spain]

BACKGROUND AND OBJECTIVE

Alpha-1-antitrypsin deficiency (AATD) is an hereditary disorder with increased risk of pulmonary emphysema and chronic liver diseases in children and adults. Since it is possible currently in Spain to apply alpha-1-antitrypsin replacement therapy to AATD patients, the objective of this study was to calculate the total number of subjects affected by PIS and PIZ AATD, and its phenotypic distribution. SUBJECTS, MATERIAL AND METHOD: Selection of published studies on allelic frequencies PIS and PIZ according to the following criteria: a) alpha-1-antitrypsin phenotyping performed by isoelectrofocusing; b) rejection of "screening studies"; c) statistic precision factor score of 5, and d) samples representative of the Spanish general population.

RESULTS

Four out 34 cohorts were selected. Mean gene frequencies (per 1,000) were: 104 (95% confidence interval [CI], 96-113) for PI*S and 17 (95% CI, 14-21) for PI*Z. These data indicated that it would exist in Spain 9,173,181 AATD subjects (95% CI, 9,167,966-9,178,398), with the following phenotypic distribution: 7,358,263 (95% CI, 6,696,222-8, 072,328) for PIMS; 1,222,041 (95% CI, 972,767-1,539,805) for PIMZ; 436,023 (95% CI, 369,057-514,244) for PISS; 144,827 (95% CI, 107,227-195,038) for PISZ; and 12,026 (95% CI, 7,788-18,493) for PIZZ. The global prevalence was 1 out of 4.4 individuals, with the following distribution: PIMS 1/5; PIMZ 1/33; PISS 1/92; PISZ 1/278; and PIZZ 1/3,344.

CONCLUSIONS

AATD is a frequent but underdiagnosed disease in Spain.

Emphysema due to alpha-antitrypsin deficiency: familial study of the YBARCELONA variant

A 39-year-old female patient, an ex-smoker with an 8-pack-year smoking history and severe pulmonary emphysema of early onset, received a diagnosis of alpha(1)-antitrypsin (AAT) deficiency and proved to be a carrier of a new deficient variant, YBARCELONA, derived from the normal M1 variant with two substitutions: one in exon III and the other in exon V. AAT genotype of eight members of the same family and study of lung function of the index case and family members at baseline and after 6 years of follow-up were performed. Five subjects were PiYM, with intermediate serum AAT concentrations and normal pulmonary function. No changes were observed over 6 years in pulmonary function of the PiYM patients who were nonsmokers; however, the PiYY index case presented worsening of pulmonary function with FEV(1) of 33%. The heterozygotes PiYM have AAT concentrations similar to the PiMZ and, at 6 years, the nonsmokers presented no worsening in pulmonary function. The risk associated with this variant in its heterozygous form may be similar to that described for PiMZ.

[Screening program for alpha-1 antitrypsin deficiency in patients with chronic obstructive pulmonary disease, using dried blood spots on filter paper]

Alpha-1 antitrypsin (AAT) deficiency is an under-diagnosed disease and screening programs have therefore been recommended for patients with chronic obstructive pulmonary disease (COPD). We present the results of the pilot phase of a screening program for AAT deficiency in order to evaluate the technique used, the procedures for transporting samples and the results obtained. Over a period of one month, five centers collected samples from all COPD patients for whom plasma concentrations of AAT or Pi phenotype had not yet been determined. Capillary blood spots were dried on filter paper and then sent by surface mail to a central laboratory for study. An immunonephelometric assay was used to determine AAT and DNA phenotyping was done by use of a Light Cycler. Samples were analyzed from 86 COPD patients (76 men, 10 women) with a mean age of 68.2 years. AAT deficiency was ruled out for 74 patients (86%) who had concentrations above the cutoff established, although one of them was MZ heterozygote by genotype. Among the 12 remaining patients (13.9%), only two also had a Z allele. The rest were individuals with concentrations below the established threshold and no evidence of a Z allele (10 patients, 11.6%). The Z allele frequency observed (3/172; 1.74%) was very similar to that found in the general population. The results of this pilot study allowed us to confirm that the method used to collect samples worked well. The sampling method is applicable, easy and well-accepted by participating physicians. It allowed AAT concentrations and Z allele deficiency to be determined. The method correlates well with standard techniques used for samples in whole blood.