Lack of association between adult asthma and the tumour necrosis factor alpha-308 polymorphism gene

Tumour necrosis factor (TNF)alpha is a cytokine endowed with potent inflamm atory properties that may contribute to airway inflammation in asthma, It h as previously been shown that the single base pair polymorphism-308 (G to A substitution) in the promoter of TNF alpha gene results in enhanced cytoki ne secretion. Whether this polymorphism is associated with the presence of phenotypic expression of asthma is questioned. In this study the relative frequency of TNF1 and TNF2 alleles in a populati on of adult healthy subjects (n=98) and adult Caucasian asthmatics (n=95) w as compared taking into account their disease severity, atopic status and t heir smoking habit. For the whole group of asthma the genotype frequency for 1/1, 1/2, 2/2 were 67%, 33% and 0%, respectively, and not significantly different from those found in the control group that reached 70%, 28% and 2% respectively (p>0.0 5). The allele frequencies in asthma were 86% and 14% for TNF1 and TNF2 res pectively while the corresponding figures were 85% and 15% in the control g roup (p>0.05). Furthermore, subdividing asthmatics into severe forced expir atory volume in one second <60% pred), atopic or smoking patients did not s how any significant association with this TNFa polymorphism. To conclude the polymorphism -308 in the promoter of the TNF<alpha> gene do es not confer a susceptibility to develop asthma nor to grade its severity.