Mutation in the TCRα subunit constant gene (TRAC) leads to a human immunodeficiency disorder characterized by a lack of TCRαβ+ T cells
Neil V. Morgan, … , Sophie Hambleton, Eamonn R. Maher
Neil V. Morgan, … , Sophie Hambleton, Eamonn R. Maher
Published January 4, 2011
Citation Information: J Clin Invest. 2011;121(2):695-702. https://doi.org/10.1172/JCI41931.
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Research Article Immunology

Mutation in the TCRα subunit constant gene (TRAC) leads to a human immunodeficiency disorder characterized by a lack of TCRαβ+ T cells

Abstract

Inherited immunodeficiency disorders can be caused by mutations in any one of a large number of genes involved in the function of immune cells. Here, we describe two families with an autosomal recessive inherited immunodeficiency disorder characterized by increased susceptibility to infection and autoimmunity. Genetic linkage studies mapped the disorder to chromosomal region 14q11.2, and a homozygous guanine-to-adenine substitution was identified at the last base of exon 3 immediately following the translational termination codon in the TCRα subunit constant gene (TRAC). RT-PCR analysis in the two affected individuals revealed impaired splicing of the mRNA, as exon 3 was lost from the TRAC transcript. The mutant TCRα chain protein was predicted to lack part of the connecting peptide domain and all of the transmembrane and cytoplasmic domains, which have a critical role in the regulation of the assembly and/or intracellular transport of TCR complexes. We found that T cells from affected individuals were profoundly impaired for surface expression of the TCRαβ complex. We believe this to be the first report of a disease-causing human TRAC mutation. Although the absence of TCRαβ+ T cells in the affected individuals was associated with immune dysregulation and autoimmunity, they had a surprising level of protection against infection.

Authors

Neil V. Morgan, Sarah Goddard, Tony S. Cardno, David McDonald, Fatimah Rahman, Dawn Barge, Andrew Ciupek, Anna Straatman-Iwanowska, Shanaz Pasha, Mary Guckian, Graham Anderson, Aarnoud Huissoon, Andrew Cant, Warren P. Tate, Sophie Hambleton, Eamonn R. Maher

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Figure 3

Identification of a homozygous G-to-A substitution in the first base following the termination codon (*1) in TRAC.

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Identification of a homozygous G-to-A substitution in the first base fol...
(A) Wild-type and mutant TRAC sequence traces. The position of the *1G>A sequence change in the patients is indicated by the arrows. The boxed sequence shows the tetranucleotide translation termination signal. (B) RT-PCR analysis of TRAC showing skipping of exon 3, which segregates within the two families. (C) Schematic showing exon structure and domains of mutant and natively spliced mRNA and sequence trace from RT-PCR of TRAC, resulting in skipping of exon 3 (exon structure adapted from IMGT repertoire; http://www.imgt.org/textes/IMGTrepertoire/).