T-Cell Immunodeficiency with Thymic Aplasia, also known as nezelof syndrome, is related to t-cell immunodeficiency, congenital alopecia, and nail dystrophy and t cell deficiency. An important gene associated with T-Cell Immunodeficiency with Thymic Aplasia is TBX1 (T-Box Transcription Factor 1), and among its related pathways/superpathways is 22q11.2 copy number variation syndrome. Affiliated tissues include thymus and skin, and related phenotypes are aplasia of the thymus and cellular immunodeficiency