Hong Kong Med J 2010;16(Suppl 4):S8-12
Sequencing analysis of the 3' region of the cagA gene in Helicobacter pylori isolated from Hong Kong Chinese patients
KF To, JHM Tong, RWM Lung, WK Leung, KW Ng
Department of Anatomical and Cellular Pathology, The Chinese University of Hong Kong, Hong Kong
1. The cagA gene is suggested as a marker for Helicobacter pylori strains with enhanced virulence, and diversity in the 3’ region of the gene may be associated with different biological activities of various strains.
2. We conducted the largest and most comprehensive series of sequence analyses of the H pylori cagA 3’ region and documented sequence variants prevailing in Hong Kong.
3. Three subtypes (1, 2, and 3) of the cagA gene were classified based on the type and number of amino acid repeats in the 3’ region. Although subtypes 2 and 3 (containing 4 copies of R1 EPIYA repeats) significantly correlated with aggressive disease, subtype 1 remained the most common strain in Hong Kong (96% of the samples).
4. 964-T/S/V variants carrying mutations in a residue adjacent to the tyrosine phosphorylation site were detected in benign lesions only. This observation should be confirmed in a larger sample, together with a functional analysis to elucidate the biological significance of these variants.