IGF1 promoter polymorphism and cranial growth in individuals born very preterm.

BACKGROUND Major defects in the IGF1 gene are associated with severely reduced cranial and linear growth. The association between IGF1 promoter polymorphisms and growth is uncertain. AIMS To test the effect of the IGF1 192-bp allele on cranial and linear growth and body mass index (BMI) from birth until age 5 years, and on IQ and serum IGF-1 at age 19 years. METHODS In a birth cohort, including 285 individuals born at a gestational age <32 weeks from the Project On Preterm and Small-for-gestational age infants (POPS), cohort anthropometric measurements were analyzed. At age 19 years IGF1 genotype, serum IGF-1 level and IQ were determined. Regression analyses were performed with mixed models. RESULTS Homozygotes for the 192-bp allele had a slower cranial growth from birth until age 5 years, and a tendency towards less brain sparing and a slower linear growth compared to the other 2 genotype groups. IGF1 genotype was not associated with IQ or BMI development. Head circumference SDS at age 5 years was positively associated with IQ at age 19 years. CONCLUSION Homozygosity for the IGF1 192-bp allele is associated with a slower cranial growth from birth until age 5 years in individuals born very preterm.