A combined T cell and B cell immunodeficiency that is caused by a mutatino in the LIG4 gene, a DNA ligase, encoding a protein essential for V(D)J recombination and DNA double-strand break (DSB) repair through nonhomologous end joining (NHEJ). Patients present with immunodeficiency and developmental and growth delay. (Human Disease Ontology, DOID_0060021)
