Cytosine-Adenosine (CA)n repeats polymorphism in IGF-I gene and early growth in infants born appropriate and small for gestational age

BACKGROUND: IGF-I gene polymorphisms might alter IGF-I level resulting in decreased foetal and postnatal growth and increased risk for diabetes mellitus type 2 and cardiovascular diseases in adulthood. OBJECTIVES: We analyzed the association between Cytosine-Adenosine (CA)(10-24) repeats polymorphism in promoter region of the IGF-I gene and early growth in infants with birth weight appropriate for gestational age (AGA) and small for gestational age (SGA). DESIGN AND METHODS: All neonates were born at term, 196 of them were AGA and 26 SGA. Blood for DNA analyses was obtained from placental part of umbilical vein. Genotyping was performed using fragment analyses of IGF-I gene promoter region. The data about postnatal growth in the group of AGA children were obtained at the age of 18 months, in SGA children at 12 months. RESULTS: No differences in the frequency of wild type allele with (CA)(19) repeats and polymorphisms with (CA)(<19) or (CA)(>19) repeats were observed between AGA and SGA children. The average birth weight and length in AGA wild type (CA)(19) homozygotes were lower in comparison with AGA carriers of various (CA)(n) polymorphisms but all observed anthropometric differences disappeared at the age of 18 months. In SGA children, no differences were found between number of (CA)(n) repeats and anthropometric parameters both at birth and at the age of 12 months. CONCLUSIONS: Although (CA)(n) repeats polymorphism in IGF-I gene might affect prenatal growth in AGA children, our results have not shown any impact of variable number of (CA)(n) repeats in IGF-I gene on postnatal growth.