LIG4 and neoplasm: DNA ligase IV defect causes the "Ligase IV syndrome" (phenotypically similar to the Nijmegen breakage syndrome, NBS) with possible typical SCID or Omenn syndrome, dysmorphic facies, microcephaly, growth retardation, psychomotor delay, skin anomalies, pancytopenia, and predisposition (also in heterozygotes) to leukemia and other neoplasia [65].