title: A novel mutation in the CD40 ligand gene in a Chinese boy with X-linked hyper-IgM syndrome.
abstract: X-linked hyper-IgM Syndrome (XHIGM) is caused by a mutation of CD40 ligand (CD40L), which is normally expressed on activated CD4+ T cells and is responsible for immunoglobulin class switching. A 7-year-old boy with recurrent sino-pulmonary infections since the age of 3 months had normal CD3+, CD4+, CD8+T lymphocytes, and CD19+B lymphocytes and NK cells, but significantly elevated IgM and extremely decreased IgG and IgA. Sequencing of genomic DNA revealed that the patient had a 34 base deletion in intron 3 and exon 4 of CD40L(g.8172_8205del34bp), which lead to the entire deletion of exon 4 in cDNA (c.347_409del63bp, i.e.,exon 4 skipping) and an in-frame deletion of 21 amino acids in CD40L protein. Moreover, the patient had negligible CD40L expression on activated CD3+CD8-T lymphocytes. His mother and sister were carriers of the CD40L mutation. Our studies demonstrated a novel mutation in CD40L, which, to our knowledge, has not been reported previously.
authors.affiliation: Department of Pediatric Hematology/Immunology, West China Second University Hospital, Sichuan University, Chengdu, China.
authors.forename: Po-Ning
authors.initials: PN
authors.lastname: Liu
authors.forename: Hong
authors.initials: H
authors.lastname: Li
authors.forename: Qiang
authors.initials: Q
authors.lastname: Li
authors.forename: Zhong-Wei
authors.initials: ZW
authors.lastname: Yin
authors.forename: Chen-Yan
authors.initials: CY
authors.lastname: Zhou
authors.forename: Ming-Yan
authors.initials: MY
authors.lastname: Jiang
authors.forename: Xia
authors.initials: X
authors.lastname: Guo
mesh_terms: D044466:Asian People; D023201:CD40 Ligand / Q000097:blood / Q000235:genetics* / Q000276:immunology; D002648:Child; D005091:Exons; D005786:Gene Expression Regulation / Q000235:genetics / Q000276:immunology; D006801:Humans; D053307:Hyper-IgM Immunodeficiency Syndrome, Type 1 / Q000097:blood / Q000235:genetics* / Q000276:immunology; D007136:Immunoglobulins / Q000097:blood / Q000276:immunology; D008214:Lymphocytes / Q000276:immunology / Q000378:metabolism; D008297:Male; D009154:Mutation
chemical_list: D007136:Immunoglobulins; D023201:CD40 Ligand