PAX1 and severe combined immunodeficiency: Importantly, PAX1 mutants (Cys368*; Asn155del and Val147Leu) were identified in otofaciocervical syndrome type 2 (OTFCS) patients with severe combined immunodeficiency (SCID), which characterized by severe T cell lymphopenia, causing increased susceptibility to viral, bacterial, and fungal infections since early in life, failed to attain T cell reconstitution after allogeneic hematopoietic stem cell transplantation (Yamazaki et al., 2020).