TRAC and severe combined immunodeficiency: We report a previously unreported homozygous TRAC variant causing a premature stop codon in three siblings with classical SCID phenotype.<h4>Methods</h4>Comprehensive immunological and molecular analyses were performed, including lymphocyte immunophenotyping, proliferation assays, qPCR for T helper (Th) subset-related gene expression, and cytokine secretion profiling.