Birth Size, Postnatal Growth and Growth during Growth Hormone Treatment in Small-for-Gestational-Age Children: Associations with IGF1 Gene Polymorphisms and Haplotypes?

Background: Short small-for-gestational-age (SGA) children experience pre- and postnatal growth restriction, which might be influenced by polymorphisms in the IGF1 gene. The well-known-841(CA)n/192 bp polymorphism has been associated with birth size and cardiovascular disease. Aims: To determine whether birth size, postnatal growth and growth during growth hormone (GH) treatment, were associated with IGF1 gene polymorphisms and haplotypes. Methods: 201 short SGA children were investigated for four IGF1 gene polymorphisms in the promoter (-G1245A,-841(CA)n), intron 2 (+3703(CT)n) and 3UTR (+A1830G). Spontaneous growth and growth during GH treatment were studied. Results: The-1245 A allele was identified as a marker-allele for the well-known-841(CA)n/non-192 bp allele, both part of haplotype 2. The-1245 A allele was not associated with head circumference at birth, but was associated with a postnatal 0.3 SDS smaller head circumference at age 1-3. The-1245 A allele was also associated with a 1-week shorter gestational age which explained the association with a smaller absolute birth size. No associations were found with gestational age-adjusted birth size, height and weight SDS during postnatal life and with growth during GH treatment. Conclusions: The-G1245A SNP appeared to be a marker for the well-known-841(CA)n/192 bp polymorphism. Haplotype 2, of which the-1245 A allele was the marker, was associated with a smaller head circumference SDS during spontaneous postnatal growth, but not during GH treatment.