efficacy of AAT augmentation therapy in patients with a rapid decline in lung function has been supported by several randomised clinical trials, it is not reimbursed in many countries and an uncertainty prevails as to which AATD patient needs treatment and when the treatment should start [11]. The multiplicity of genotypes and the variable clinical presentation makes the counselling of AATD individuals challenging [12] and may result in both under- and overtreatment. Compared to lung involvement, liver affection has been studied even less and the burden of liver disease in AATD is only recently being appreciated [7, 8]. On the bright side, strong multinational registries have emerged and are likely to become particularly useful in uncovering the relevance of rare AATD genotypes as well as rare disease manifestations [13]. While liver transplantation still constitutes the only curative treatment option in end-stage liver disease related to AATD, multiple clinical studies are underway and use either RNA silencing or small molecules to counteract proteotoxic liver injury [8]. Moreover, the usefulness of AAT as an immunomodulatory protein is receiving more and more attention, and AAT augmentation therapy shows promise in the treatment of various immune-mediated disorders such as graft-versus-host disease [14]. Whether associated with severe deficiency alleles as a homozygous or heterozygous combination, AATD can be viewed both as a frequent condition and a rare disease. As a result, physicians of multiple disciplines, who systematically test for the presence of AATD, are confronted with many different genotypes as well as a highly variable clinical presentation. In addition, patients are often waiting for a correct diagnosis and are in need of evidence-based counselling explaining both the typical disease manifestations and the disease course [10, 12]. The knowledge and the standards of treatment also vary substantially between countries. With all this in mind, the goal of this Monograph is to provide a comprehensive and up-to-date overview, that covers most aspects of AATD. We have tailored the information to the physician taking care of lung and liver patients in daily practice, but have also included useful information for general practitioners who are responsible for the medical guidance of these patients. The book covers basic biology [1, 4, 5], genetics [2, 12], laboratory diagnostics [3] and the major organ manifestations. It describes the clinical presentation of AATD in both adults and children [6–9, 11], and includes chapters on genetic counselling, patient views and future therapies [10, 12, 14]. The authors of the individual chapters have produced a practice-guideline publication that comprises information on scientific background as well as application at the patient’s bedside. We would like to thank all authors for their hard work and involvement in the writing of this publication. We hope that this book will raise awareness about this underdiagnosed condition and improve the everyday life of individuals with AATD. References 1. Lomas DA, Irving JA, Gooptu B. Serpinopathies. In: Strnad P, Brantly ML, Bals R, eds. ɑ1-Antitrypsin Deficiency (ERS Monograph). Sheffield, European Respiratory Society, 2019 pp. 6–26. 2. Hobbs BD, Silverman EK, Cho MH. Genetics and epidemiology. In: Strnad P, Brantly ML, Bals R, eds. ɑ 1 -Antitrypsin Deficiency (ERS Monograph). Sheffield, European Respiratory Society, 2019 pp. 27–38. 3. Ferrarotti I, Ottaviani S. Laboratory diagnosis. In: Strnad P, Brantly ML, Bals R, eds. ɑ1-Antitrypsin Deficiency (ERS Monograph). Sheffield, European Respiratory Society, 2019 pp. 39–51. 4. Piccolo P, Attanasio S, Brunetti-Pierri N. Mechanisms of liver disease. In: Strnad P, Brantly ML, Bals R, eds. ɑ1-Antitrypsin Deficiency (ERS Monograph). Sheffield, European Respiratory Society, 2019 pp. 93–104. x https://doi.org/10.1183/2312508X.10026219