Non classical HLA genes and non-HLA genes in a population of infants at familial risk of atopy.

Aim: We investigated on parental history and IgE serum level in 2588 consecutive newborns to individuate babies "at risk" of atopy at birth and we analysed the polymorphisms of class III region to evaluate the association with immunogenetic markers of HLA: C4A, C4B, LTA, RAGE and TNFA genes; we performed TNF and IgE receptor (FCERB1) physiologically related gene polymorphisms.

Result: 791 babies/2588 (30.6%) were considered "at risk" for atopy and followed-up: 400 had familial history of atopy (at least one parent or sibling), 256 had IgE >0.35 kUA/l at birth and during the follow-up and 135 were positive for both conditions. The allele C4B2 was significantly more frequent in the sample of babies at risk (22.1% vs 10%, p< 0.001). Furthermore, the mean value of IgE at birth in babies carrying the allele C4B2 was 2.26 KUA/l versus 0.74 KUA/l in those not carrying this allele (p=0.01). No significant association emerged for RAGE at the centromeric end of class III region and for LTA, TNFA at the telomeric one. TNFRI, TNFRII and FCERB1 gene polymorphisms also seemed not implicated.

Conclusion: Our study confirms that HLA class III region seems involved in familial predisposition to atopy, and C4B gene probably acts as a marker of a more restricted subregion.