Characteristics of gene mutations in Vietnamese pediatric patients with Inborn Errors of Immunity: a cross-sectional study

Inborn Errors of Immunity (IEIs) are rare genetic disorders that cause immunodeficiency. Diagnosis and classification of these disorders are challenging due to the heterogeneous clinical manifestations and genetic mutations. This is the first study to fully describe the spectrum of gene mutations and genetic diversity of IEIs in Vietnamese pediatric patients. A cross-sectional study was conducted on pediatric patients diagnosed with IEIs at Children’s Hospital 1, Vietnam, from 2014 to 2024. Ninety-two patients with identified mutations were enrolled. Genetic testing was performed using Sanger, fluorescence in situ hybridization, and whole exome sequencing to identify pathogenic variants. Clinical and epidemiological data were collected from medical records and mutations were classified according to the IUIS 2024 classification. The study identified 99 mutations in 33 different genes, with X-linked inheritance being predominant (53.2%). The antibody deficiency and immune dysregulation groups were the most common (22.8% for each mutation). Nineteen novel mutations were identified, all of which were predictively classified as pathogenic or likely pathogenic. The majority of mutations caused protein truncations, leading to loss of function, especially in the immunodeficiencies affecting cellular and humoral immunity and the phagocyte disorder groups. Clinical manifestations differed markedly between the different gene groups, highlighting the complexity of diagnosing IEIs. The number of cases with mutations causing X-linked inheritance was dominant, which was similar to studies from Asian countries, though different from studies from Africa due to the rates of consanguineous marriage. In addition, the variability between clinical phenotype and genotype in IEIs noted from our study has been a significant obstacle to the classification of diseases and their efficient treatment. This is the largest single center cohort to date in Vietnam to describe gene mutations in children with IEIs. The results of the study emphasize the importance of genetic testing in the diagnosis and treatment of IEIs, and open possible directions for further research for novel mutations.