Deletion syndrome 22q11.2 (22q11.2DS) is the most common microdeletion syndrome in humans, with a prevalence in the general population of approximately 1 in 4000 live births. The genetic basis of 22q11.2DS lies in the deletion of region 11.2 on the long arm of chromosome 22. Due to the instability of this region and its susceptibility to mutations, the syndrome comprises a heterogeneous group of diseases with different phenotypes, of which DiGeorge syndrome (DGS) is the best known. The deletion of the 22q11.2 region affects a large number of genes, some of which are crucial for the development of various organ systems. This leads to a broad spectrum of clinical symptoms that can occur at different stages of life, including prenatal, infancy, childhood and even adulthood. These symptoms can range from mild to severe and often include congenital heart defects, facial anomalies, thymic hypoplasia, hypoparathyroidism and cleft palate. Most diagnoses are made early in life, with congenital heart defects being one of the fundamental abnormalities in establishing the clinical diagnosis of 22q11.2DS. The aim of this thesis was to present different clinical characteristics of these patients and four patients who presented with a different clinical picture, complicating the diagnosis and leading to a later diagnosis of 22q11.2 deletion syndrome. The focus was on a multidisciplinary and comprehensive approach to the detection and treatment of patients with this syndrome, emphasizing the importance of genetic testing, which is now the primary diagnostic method for confirming the disease. Timely genetic testing enables accurate diagnosis, which is crucial for planning appropriate treatment and monitoring of patients. However, it also has an important role in genetic counseling of families about the risks of the disease occurring in offspring and the possibilities of prenatal diagnosis.