title: Di-nucleotide repeat polymorphisms of the insulin-like growth factor-1 gene and their association with IGF-1, insulin-like growth factor-binding protein-1 and birth size in a Sri-Lankan cohort.
abstract: BACKGROUND
  Insulin-like growth factor (IGF)-I is implicated in fetal growth. Ethnic variations of IGF-1 have also been suggested. Di-nucleotide repeat polymorphisms of the IGF-1 gene or their association with IGF-1 levels and birth size have not been studied in Sri Lankans.
  
  
  OBJECTIVE
  To describe IGF-1 di-nucleotide repeat polymorphisms and their association with IGF-1 and IGF-binding protein (IGFBP)-1 levels and birth size in a cohort of Sri Lankans.
  
  
  METHODS
  A cross-sectional study on 200 mother-newborn pairs was carried out. Maternal and cord blood levels of IGF-1 and IGFBP-1 were measured by enzyme-linked immunosorbent assay. Three di-nucleotide repeat polymorphisms of the IGF-1 gene [cytosine-adenine (CA) repeats in the promoter and 3' regions and intron 2 cytosine-thymine (CT) repeat] were studied using PCR amplification and fragment analysis.
  
  
  RESULTS
  Cord blood IGFBP-1 levels correlated negatively with birth weight (p < 0.01) and crown-heel length (p < 0.05). Wild-type alleles of the CA repeat polymorphisms differed from those reported in other populations. Newborn and maternal intron 2 CT repeat polymorphism showed a significant effect on birth weight (p < 0.01 and p < 0.001, respectively), crown-heel length (p < 0.01) and head circumference (p < 0.01 and p < 0.05, respectively). Promoter region CA repeat polymorphism and intron 2 CT repeat polymorphism in the newborns were significantly (p < 0.05) associated with cord blood IGF-1 levels. Almost all these effects were limited to primiparous pregnancies.
  
  
  CONCLUSIONS
  In Sri Lankans intron 2 CT repeat polymorphism of the IGF-1 gene appears to be a significant contributor to IGF-1 levels and birth size in primiparous pregnancies.
authors.affiliation: Institute of Biochemistry, Molecular Biology and Biotechnology, University of Colombo, Colombo, Sri Lanka.
authors.forename: P
authors.initials: P
authors.lastname: Jayanthiny
authors.forename: K H
authors.initials: KH
authors.lastname: Tennekoon
authors.forename: E H
authors.initials: EH
authors.lastname: Karunanayake
authors.forename: J M
authors.initials: JM
authors.lastname: Kumarasiri
authors.forename: A P D S
authors.initials: AP
authors.lastname: Wijesundera
mesh_terms: D000328:Adult; D001724:Birth Weight / Q000235:genetics; D049628:Body Size / Q000235:genetics*; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D018900:Dinucleotide Repeats / Q000235:genetics / Q000502:physiology; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D018970:Insulin-Like Growth Factor Binding Protein 1 / Q000097:blood*; D007334:Insulin-Like Growth Factor I / Q000032:analysis* / Q000235:genetics* / Q000378:metabolism; D008297:Male; D010298:Parity / Q000502:physiology; D036801:Parturition / Q000097:blood* / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D011110:Polymorphism, Genetic / Q000502:physiology; D011247:Pregnancy; D013188:Sri Lanka; D055815:Young Adult
chemical_list: D018970:Insulin-Like Growth Factor Binding Protein 1; D007334:Insulin-Like Growth Factor I