An association study between the Clara cell secretory protein CC16 A38G polymorphism and asthma phenotypes.
BACKGROUND
Previously, an association has been reported between an increased risk of asthma and a polymorphism in the Clara cell secretory protein (CC16) gene [namely, an adenine to guanine substitution in the CC16 gene at position 38 (A38G) downstream from the transcription initiation site within the noncoding region of exon 1]. Homozygous individuals for the polymorphic sequence (AA genotype) were reported to have a significant (6.9 fold) increased risk of developing asthma. This finding has not been confirmed independently.


OBJECTIVE
To validate the association of CC16 A38G polymorphism to asthma in a separate well-characterized population through a case-control study.


METHODS
We conducted an association study using a sample of 217 unrelated Northern European Caucasians. Individuals were clinically characterized by a validated respiratory questionnaire, spirometry and bronchial reactivity measurement, and genotyped for the A38G polymorphism using PCR and restriction digestion. Association analysis was performed using the nonparametric Chi-squared tests.


RESULTS
In the unselected population, 43.3% participants were homozygous for the CC16*G allele and 45.4% were heterozygous (AG). We observed no significant difference in the distribution of positive bronchial reactivity to methacholine (at FEV1 PC20 of </= 8 mg/mL) across the three genotypes. Homozygous individuals for the CC16*A allele did not demonstrate an increased risk of asthma when compared to heterozygous or GG homozygotes. In addition, no significant difference was observed in the distribution of the CC16*A or *G alleles in the asthmatics vs. non-asthmatics.


CONCLUSIONS
CC16 polymorphism A38G does not influence the predisposition to asthma in this sample.
Mansur
A H
AH
Lung Injury & Inflammation Group, Department of Respiratory Medicine, Keele University and North Staffordshire Hospital, Staffordshire, UK. adelmansur@hotmail.com
Fryer
A A
AA
Hepple
M
M
Strange
R C
RC
Spiteri
M A
MA
D000293:Adolescent; D000328:Adult; D001249:Asthma / Q000235:genetics*; D016535:Bronchial Hyperreactivity / Q000235:genetics; D002874:Chromosome Mapping; D005260:Female; D005838:Genotype; D006801:Humans; D008297:Male; D008875:Middle Aged; D010641:Phenotype; D011110:Polymorphism, Genetic; D011506:Proteins / Q000235:genetics*; D014598:Uteroglobin
D011506:Proteins; C556389:SCGB1A1 protein, human; D014598:Uteroglobin