LIG4 syndrome

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LIG4 syndrome
Synonyms	Ligase IV syndrome
Pronounce
Specialty	Clinical genetics
Symptoms	Microcephaly, developmental delay, immunodeficiency, facial dysmorphism
Complications	N/A
Onset	Congenital
Duration	Lifelong
Types	N/A
Causes	Mutations in the LIG4 gene
Risks
Diagnosis	Genetic testing, clinical evaluation
Differential diagnosis	Nijmegen breakage syndrome, Ataxia-telangiectasia, Seckel syndrome
Prevention	Genetic counseling
Treatment	Hematopoietic stem cell transplantation, supportive care
Medication
Prognosis	Variable, depending on severity
Frequency	Rare
Deaths

LIG4 syndrome is a rare autosomal recessive genetic disorder characterized by hypersensitivity to ionizing radiation and a propensity to develop malignancies. The syndrome is caused by mutations in the LIG4 gene, which is involved in the repair of DNA double-strand breaks.

Symptoms and Signs

Patients with LIG4 syndrome typically present with a variety of clinical manifestations, including microcephaly, unusual facial features, growth retardation, and immunodeficiency. They may also have a higher risk of developing leukemia and lymphoma.

Genetics

LIG4 syndrome is caused by mutations in the LIG4 gene, which encodes a DNA ligase that is essential for the repair of DNA double-strand breaks. These breaks can occur spontaneously during DNA replication or can be induced by ionizing radiation or certain chemicals. The LIG4 protein is involved in the non-homologous end joining (NHEJ) pathway, which is one of the major pathways for repairing these breaks.

Diagnosis

The diagnosis of LIG4 syndrome is based on clinical features, laboratory findings, and the identification of a pathogenic mutation in the LIG4 gene. Laboratory findings may include lymphopenia, anemia, and increased levels of gamma globulin.

Treatment

There is currently no cure for LIG4 syndrome. Treatment is supportive and may include regular monitoring for malignancies, immunoglobulin replacement therapy for immunodeficiency, and avoidance of ionizing radiation.

See Also

• DNA repair
• Non-homologous end joining
• Genetic disorders

References

• O'Driscoll M, Cerosaletti KM, Girard PM, et al. DNA ligase IV mutations identified in patients exhibiting developmental delay and immunodeficiency. Molecular Cell. 2001;8(6):1175-1185.
• Buck D, Malivert L, de Chasseval R, et al. Cernunnos, a novel nonhomologous end-joining factor, is mutated in human immunodeficiency with microcephaly. Cell. 2006;124(2):287-299.

NIH genetic and rare disease info

• NIH info on LIG4 syndrome

LIG4 syndrome is a rare disease.

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