Characteristics of diseases in children with inherited α1-antitrypsin deficiency

Abstract

The article presents the current views on genetics, features of metabolic disorders, course of various clinical manifestations, diagnostic criteria, and treatment principles for monogenic enzymopathy — an inherited α1;antitrypsin (AAT) deficiency.

Inherited AAT deficiency manifests itself as four clinical syndromes: respiratory disease (pulmonary emphysema, chronic obstructive pulmonary disease (COPD), bronchial asthma, spontaneous pneumothorax, bronchiectasis); liver disease and blood vessel damage. Respiratory disease manifests itself between the ages of 20–40 years. Chronic pulmonary emphysema is typical for homozygous PiZZ gene carriers. The most unfavorable clinical course variant including persistent cough, COPD development, bronchial asthma, pneumonia, co-existence of various respiratory diseases and severe disorders of external respiration is the PISZ phenotype. Bronchial asthma has severe clinical course with torpid purulent endobronchitis; is often uncontrolled despite background therapy. In COPD patients, exacerbations are frequent, severe, and prolonged. The reduction in the vessels of the pulmonary circulation results in pulmonary hypertension, right ventricular failure. In AAT deficiency, there is a high incidence of bronchiectasis, lung cancer. Liver diseases manifest themselves as neonatal hepatitis, biliary atresia, liver cirrhosis, infectious complications. Chronic form is characterized by subclinical changes in the biochemical parameters of liver function most of which (up to 70%) normalize before the age of 18 years. In patients until the age of 20 years, disease slowly progresses and leads to the development of liver cirrhosis in 30% of cases, while older patients develop liver cirrhosis in 30–50% of cases. Some patients have a benign course of liver disease and present with hepatomegaly.

Hemorrhagic syndrome occurs when protease inhibitor gene product acquires the properties of antithrombin. Vascular disease manifests itself as necrotizing panniculitis, severe hemorrhagic vasculitis with serum antineutrophil cytoplasmic antibodies to proteinase (С-АNСА). AAT deficiency may coexist with systemic vasculitis, vascular aneurysm, many other diseases, as well as with the development of aplastic processes of various localization.

In addition to clinical manifestations, diagnosis of inherited AAT deficiency includes screening programs, instrumental (X-ray, spirometry, ECG, ultrasound), laboratory (liver function, coagulation profile, immunogram, serum AAT concentration), genetic investigations, exclusion testing for cystic fibrosis, viral hepatitis, and other diseases.

Treatment of patients with inherited AAT deficiency consists in adequate nutrition and physical activity; treatment of pre-existing conditions; prevention and timely therapy for respiratory infections; pathogenetic therapy. Pathogenetic therapy for AAT deficiency is a replacement (augmentation) therapy with exogenous α1-antitrypsin concentrate. Replacement therapy is indicated only in patients >18 years of age with the PiZZ phenotype or other rare AAT phenotypes.

No conflict of interest was declared by the author.