Transcriptional regulatory defects in the first intron of Bruton's tyrosine kinase
Authors: Shin, Dong-Min; Jo, Eun-Kyeong; Kanegane, Hirokazu; Futatani, Takeshi1; Zhao, Meina1; Song, Chang-Hwa; Yamagishi, Atsushi2; Miyawaki, Toshio1
Source: Pediatrics International, Volume 50, Number 6, December 2008 , pp. 801-805(5)
Publisher: Blackwell Publishing
Abstract:
Background: X-linked agammaglobulinemia (XLA), characterized by the early onset of recurrent bacterial infections, profound hypogammaglobulinemia, and a markedly diminished number of peripheral B lymphocytes, is caused by mutations in the Bruton's tyrosine kinase (BTK) gene. The >600 unique mutations identified to date include single base pair substitutions, small insertions or deletions, and gross deletions. A few cases, however, have been found to have no mutations in the coding region even with reduced BTK mRNA or protein expression. Mutations in intron 1 positions +5 (G→A) and +6 (T→G) of the BTK gene have been identified, and these changes were associated with reduced transcriptional activity. Methods: In the present study a novel mutation in intron 1 position +5 (G→T) was identified in a Japanese patient with XLA. The reporter constructs containing these mutations were made, and the reporter activities were measured using a luciferase assay. Results: All the mutant constructs were demonstrated to have reduced transcriptional activity. Conclusions: Positions +5 and +6 in intron 1 of the BTK gene are critical for transcriptional activity, and defects in these regions cause XLA.Keywords: Bruton's tyrosine kinase; intron 1; transcriptional regulatory elements; X-linked agammaglobulinemia
Document Type: Research article
DOI: 10.1111/j.1442-200X.2008.02739.x
Affiliations: 1: Department of Pediatrics, Graduate School of Medicine, University of Toyama, Toyama 2: Department of Pediatrics, Takayama Red Cross Hospital, Takayama, Japan

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