[A study on the relationship between interleukin-4 promoter polymorphism and asthma in a Xinjiang Uyger population]

Abstract

Objective: To investigate the potential association of interleukin-4 (IL-4) polymorphism-589 (C/T) with specific clinical phenotypes of asthma in Xinjiang Uygur population.

Methods: Ninety-three Uyger asthmatics [asthmatic group (A), mild 30 (A(1)), moderate 32 (A(2)), severe 31 (A(3)); nocturnal asthma 41 (A(I)), non-nocturnal asthma 52 (A(II))] in whom linkage of asthma and atopy to chromosome 5q(31 - 33) was suggested and 62 normal healthy controls (B group) with the same ethnicity nearby Xinjiang Hetian region were investigated. The IL-4-589 (C/T) polymorphism was genotyped by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis. The serum eosinophil cationic protein (ECP) and total IgE and specific aeroallergens were detected using a Pharmacia UniCAP 100 type instrument, and pulmonary ventilatory function was measured by FEV(1)% and PEF.

Results: The IL-4 polymorphism-589 (C/T) frequency of the heterozygous CT was 42 (45.1%), homozygous CC 29 (31.2%), and homozygous TT 22 (23.7%) in A group. The frequency of the heterozygous CT was 26 (41.9%), homozygous CC 21 (33.9%), and homozygous TT 15 (24.2%) in B group. There were no significant differences in the distributions of the three genotypes between A group and B group (P > 0.05). The frequency of the homozygous CC was 39.0% in the A(I) group as compared to 25.0% in the A(II) group, the difference being significant (P = 0.026). The frequency of the heterozygous CT was 40% (12/30) in A(1) group, 41% (13/32) in A(2) group and 55% (17/31) in A(3) group. There were significant differences in the distributions of the three genotypes among A(1), A(2) and A(3) group (all P < 0.05). The total serum IgE levels were (75.2 +/- 43.2) kU/L and (52.3 +/- 22.4) kU/L in A group and B group respectively, and there was no significant difference in the levels of total serum IgE among the genotypes in both A and B groups (P > 0.05). The serum ECP levels were (7.9 +/- 5.4) microg/L and (4.8 +/- 1.9) microg/L in A group and B group respectively, the difference being significant between the two groups (P < 0.01). The positive rate of specific IgE antibody was 18.3% (17/93), and 0% (0/62) in A group and B group respectively, and there was significant difference between the two groups (P < 0.01).

Conclusions: It is suggested that the IL-4 promoter-589 (C/T) polymorphism may be associated with nocturnal phenotypes of asthma, but not associated with pulmonary ventilatory function (P > 0.05) and serum total IgE level in this Xinjiang Uyger population.