CHTF18 and Immunodeficiency: While sequencing of known genes implicated in immunodeficiency revealed no mutations, whole exome sequencing (WES) revealed several potential variants, with the most likely variants being mutations in CTBP2 and CHTF18. CTBP2 is a transcriptional corepressor which binds Proline-Isoleucine-Aspartate-Leucine-Serine (PIDLS) to repress target genes, including IL-2 (48, 49).