Epidemiological and Clinical Characteristics of Hereditary Angioedema in the Baltic States

Natalja Kurjane^1,2*Adine Kanepa^1,2Signe Purina^1,3Lasma Lapina^1,3Krista Ress⁴Marget Savisaar⁵Ieva Bajoriuniene⁶Edita Gasiuniene⁷Kotryna Linauskiene⁸Anželika Chomičienė⁸Brigita Gradauskiene⁷Laura Malinauskiene⁸

• ¹Riga Stradiņš University, Riga, Latvia
• ²Paula Stradiņš Clinical University hospital, Center for Clinical Immunology and Allergology, Riga, Latvia
• ³Allergic Diseases Diagnosis and Treatment Centre, Riga, Latvia
• ⁴East Tallinn Central Hospital, Centre of Allergology and Immunology, Tallinn, Estonia
• ⁵Tartu University Hospital, Lung Clinic, Tartu, Estonia
• ⁶Centre of Primary Immunodeficiency, Lithuanian University of Health Sciences, Kaunas, Lithuania
• ⁷Centre of Primary Immunodeficiency, Department of Immunology and Allergology, Lithuanian University of Health Sciences, Kaunas, Lithuania
• ⁸Vilnius University, Faculty of Medicine, Institute of Clinical Medicine, Clinic of Chest Diseases, Immunology and Allergology, Vilnius, Lithuania

Background: Hereditary angioedema (HAE) is a rare, potentially life-threatening disorder characterised by recurrent episodes of localised oedema caused by bradykinin overproduction. Accurate epidemiological data are essential for optimising diagnosis and treatment, particularly in underrepresented regions such as the Baltic states. This study aimed to examine the prevalence, clinical characteristics, genetic variants, and treatment accessibility for patients with HAE in the Baltic states of Estonia, Latvia, and Lithuania. Methods: This retrospective study included HAE patients diagnosed according to the WAO/EAACI 2021 criteria between 2004 and 2024. Demographic, clinical, and genetic data were collected and evaluated. Descriptive statistical analysis was performed using Jamovi (version 2.3). Results: A total of 78 patients were identified in Estonia (n=30), Latvia (n=12) and Lithuania (n=36) from 2004 till 2024. In Lithuania, 7 patients had died and 3 were lost to follow-up, resulting in 26 patients remaining under active observation. While the total number of HAE cases identified across the three countries was reported, detailed clinical data and analyses were limited to the 68 patients who were alive and actively followed at the time of data collection. Estonia exhibited the highest point prevalence (2.19 per 100,000), while Latvia had the lowest (0.65). The median diagnostic delay was longest in Latvia (24 years) and shortest in Estonia (9.5 years). SERPING1 gene pathogenic variants predominated. Estonia had the broadest availability of treatments, whereas Latvia had restricted access to modern therapies. Conclusion: Considerable variation exists in HAE prevalence, diagnosis, and treatment across the Baltic states. Estonia exemplifies best practices, while Latvia remains underserved. Regional collaboration and standardised care protocols are urgently needed.