FAS and Autoimmunity: <h4>Background</h4>Autoimmune lymphoproliferative syndrome (ALPS) is a rare disease characterized by defective <i>FAS</i> signaling, which results in chronic, nonmalignant lymphoproliferation and autoimmunity accompanied by increased numbers of "double-negative" T-cells (DNTs) (T-cell receptor αβ+ CD4-CD8-) and an increased risk of developing malignancies later in life.<h4>Case presentation</h4>We herein report a case of a newborn boy with a novel germline homozygous variant identified in the <i>FAS</i> gene, exon 9, c.775del, which was considered pathogenic.