All issues > Volume 49(12); 2006

Original Article

Korean J Pediatr. 2006;49(12):1340-1347. Published online December 15, 2006.

Analysis of cytosine adenine(CA) repeat polymorphism of the IGF-I gene and influence on serum IGF-I levels in healthy children and adolescents

Myung Jin MJ Ko¹, Tae Gyu TG Hwang¹, Jeong Nye JN Lee², Woo Yeong WY Chung¹

¹Department of Pediatrics, College of Medicine, Inje University, Busan, Korea
²Department of Laboratory Medicine, College of Medicine, Inje University, Busan, Korea

Correspondence Woo Yeong WY Chung ,Email: chungwy@chol.com

Abstract

Purpose
: The aim of the present study was to investigate the role of polymorphic cytosine adenine (CA) repeat of the IGF-I gene in the age-related alterations of serum IGF-I levels in healthy children.
Methods
: Two hundred and forty three normal healthy children (136 boys; 107 girls) aged between 7 and 15 years were enrolled in the present study. The primers were designed to cover the promoter regions containing the polymorphic CA repeat. Data were analyzed using GeneMapper software, version 3.7. All analyses were performed using MEDCALC software packages.
Results
Deletion of 2 bp (G, A) following 3' of CA repeat were observed in all Korean children. The CA repeat sequences ranged from 17 to 23, and 19 CA repeat were the most common with an alleles frequency of 39.3 percent. Considering genotypes, 63.8 percent of subjects were homozygote or heterozygote for 19 CA repeat (192 bp allele), suggesting that this is wild type allele from which all other alleles originated in Korean children. Homozygote for 19 CA repeat were 14.7 percent, heterozygote for 19 CA repeat was 49.1 percent and 19 CA noncarriers totalled 36.2 percent. In 19 CA repeat noncarriers, the mean height, weight and serum IGF-I level were lower compared with those of 19 CA homozygous carriers, but statistically not significant. Correlations between serum IGF-I level and age according to the IGF-I genotypes revealed statistically significant relationships in the all groups, in the 19 CA repeat carrier group and, even in the noncarrier group.
Conclusions
: There were no significant differences of the mean height, weight and serum IGF-I levels among three different genotype groups. Also, there were no significantly different correlations between 19 CA repeat polymorphisms and serum IGF-I levels, according to genotype. Our results suggest that the IGF-I 19 CA repeat gene polymorphism is not associated with circulating IGF-I levels in healthy children.

Keywords :Serum , IGF-I level , 19 CA polymorphism , IGF-I gene , Healthy children