This syndrome is characterized by cellular radiation sensitivity, growth retardation, developmental delay, microcephaly, facial dysmorphisms, increased disposition to leukemia, variable degrees of immunodeficiency and reduced number of blood cells.

[7][8] Accumulation of DNA damage leading to stem cell exhaustion is regarded as an important aspect of aging.

[9][10] Deficiency of lig4 in pluripotent stem cells impairs Non-homologous end joining (NHEJ) and results in accumulation of DNA double-strand breaks and enhanced apoptosis.

[8] Lig4 deficiency in the mouse causes a progressive loss of haematopoietic stem cells and bone marrow cellularity during aging.

Nucleophilic attack by the 3' hydroxyl group of a second DNA end and release of AMP yield the ligation product.