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Severe combined immunodeficiency and microcephaly in siblings with hypomorphic mutations in DNA ligase IV
Author(s) -
Buck Dietke,
Moshous Despina,
de Chasseval Régina,
Ma Yunmei,
le Deist Françoise,
CavazzanaCalvo Marina,
Fischer Alain,
Casanova JeanLaurent,
Lieber Michael R.,
de Villartay JeanPierre
Publication year - 2006
Publication title -
european journal of immunology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.272
H-Index - 201
eISSN - 1521-4141
pISSN - 0014-2980
DOI - 10.1002/eji.200535401
Subject(s) - dna ligase , biology , ku80 , ku70 , v(d)j recombination , homologous recombination , non homologous end joining , dna repair , dna repair protein xrcc4 , microcephaly , severe combined immunodeficiency , genetics , microbiology and biotechnology , immunodeficiency , mutation , dna , cancer research , gene , dna mismatch repair , recombination , dna binding protein , immune system , transcription factor
Abstract DNA double‐strand breaks (dsb) during V(D)J recombination of T and B lymphocyte receptor genes are resolved by the non‐homologous DNA end joining pathway (NHEJ) including at least six factors: Ku70, Ku80, DNA‐PK cs , Artemis, Xrcc4, and DNA ligase IV (Lig4). Artemis and Lig4 are the only known V(D)J/NHEJ factors found deficient in human genetic disorders. Null mutations of the Artemis gene result in a complete absence of T and B lymphocytes and increased cellular sensitivity to ionizing radiations, causing radiosensitive‐SCID. Mutations of Lig4 are exclusively hypomorphic and have only been described in six patients, four exhibiting mild immunodeficiency associated with microcephaly and developmental delay, while two patient had leukemia. Here we report a SCID associated with microcephaly caused by compound heterozygous hypomorphic mutations in Lig4. Residual activity of Lig4 in these patients is underscored by a normal pattern of TCR‐α and ‐β junctions in the T cells of the patients and a moderate impairment of V(D)J recombination as tested in vitro . These observations contrast with the severity of the clinical immunodeficiency, suggesting that Lig4 may have additional critical roles in lymphocyte survival beyond V(D)J recombination.