Polymorphisms in the P1 promoter of the IGF-1 gene in children with growth disorders.

Background/aims: The aim of this study was to associate children's growth disorders with polymorphisms detected in the P1 promoter region of IGF1 (including SNP and (CA) n microsatellite repeat polymorphism) and IGF1 and IGFPB3 levels.

Methods: IGF-1 gene P1 promoter polymorphism was analyzed in DNA obtained from the blood of 51 children with growth disorders and 50 healthy children without growth disorders by means of PCR-SSCP and sequencing.

Results: Among children with growth disorders and the control group we found previously described polymorphisms in the P1 promoter of the IGF-1 gene (rs35767, rs5742612) and different genotypes. The frequency of both detected polymorphisms was no significantly different in the study and the control groups. The CA repeat sequence within the group of children in the study ranged from 11 to 21. The most common were homozygote 19/19 (49.02%) and heterozygote 19/20 (27.45%). Our results did not show any association between polymorphisms in the P1 promoter and IGF-1 levels in the serum of children with growth disorders.

Conclusions: This study demonstrated that SNP and (CA) n microsatellite repeat polymorphisms by themselves are not the primary regulatory elements of IGF-1 expression. However, our bioinformatics analysis has shown that the (CA) n microsatellite region in the P1 promoter of IGF-1 is able to form DNA loop structures which can modulate transcription.