Severe Combined Immunodeficiency Due to Foxn1 Deficiency, also known as severe t-cell immunodeficiency-congenital alopecia-nail dystrophy syndrome, is related to t-cell immunodeficiency, congenital alopecia, and nail dystrophy and severe combined immunodeficiency. An important gene associated with Severe Combined Immunodeficiency Due to Foxn1 Deficiency is FOXN1 (Forkhead Box N1). Affiliated tissues include t cells and bone marrow, and related phenotypes are immunodeficiency and nail pits