22q11.2 microdeletion and immunological status of Vietnamese children with tetralogy of Fallot and pulmonary atresia with ventricular septal defect

The 22q11.2 deletion (22q11.2Del) is one of the most common chromosomal microdeletions associated with a broad range of clinical manifestations, including congenital heart disease and immunodeficiency. Several studies reported a high frequency of 22q11.2Del in patients with conotruncal cardiac anomalies. Altered immune cell composition was also observed in cases of cardiac malformation. Our study aimed to describe the prevalence of 22q11.2Del and the immunological status of Vietnamese patients with Tetralogy of Fallot (TOF) and pulmonary atresia with ventricular septal defect (PA-VSD). This cross-sectional study included 210 patients with TOF and PA-VSD. The 22q11.2Del was detected using multiplex ligation-dependent probe amplification (MLPA). 22q11.2Del cases were subsequently confirmed by next-generation sequencing. Blood lymphocytes were assessed by flow cytometry, and immunoglobulin levels were measured by ELISA. We identified 22 patients (10.47%) with different types of 22q11.2Del. In particular, the LCR22A-LCR22D deletion type was detected in most cases (77.27%), followed by the LCR22A-LCR22B deletion (9.09%), the LCR22A-LCR22C deletion (9.09%), and the LCR22C-LCR22D deletion (4.55%). No differences in cardiac function and interventional history were observed between the 22q11.2Del and non-deletion groups. In patients with 22q11.2Del, we observed a significant reduction in the T-cell CD4/CD8 ratio and increased IgA levels. A considerable prevalence of 22q11.2Del was observed in Vietnamese patients with TOF and PA-VSD, although deletion types varied. Some immunological changes were observed in patients carrying both 22q11.2Del and cardiac anomalies.