Maternal 25-hydroxyvitamin D concentration and offspring birth size: effect modification by infant VDR genotype.
OBJECTIVE
We tested the hypothesis that the relationship between maternal 25-hydroxyvitamin D (25-(OH)D) and offspring birth size differs according to offspring vitamin D receptor (VDR) genotype (Apa1, Bsm1, Fok1 or Taq1).


METHODS
Mothers of 354 singleton babies had serum 25-(OH)D concentration measured at 28-30 weeks of gestation and consented to measurement of their babies soon after birth. DNA was extracted from the babies' Guthrie cards.


RESULTS
There was evidence of effect modification by infant FokI genotype. Babies of deficient mothers had lower birth weight with FF or Ff, but not ff genotype (P-value for interaction after adjustment for potential confounding factors=0.02), but thicker subscapular and suprailiac skinfolds with ff, but not FF or Ff genotype (P=0.008 and 0.02, respectively). Sample size was insufficient to investigate effect modification by the other VDR polymorphisms.


CONCLUSIONS
These preliminary findings suggest that studies of maternal vitamin D status and birth size may need to take VDR genotype into account.
Morley
R
R
Clinical Epidemiology and Biostatistics Unit, Department of Paediatrics, University of Melbourne, Melbourne, Victoria, Australia. ruth.morley@mcri.edu.au
Carlin
J B
JB
Pasco
J A
JA
Wark
J D
JD
Ponsonby
A-L
AL
D000328:Adult; D001724:Birth Weight / Q000235:genetics*; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D020641:Polymorphism, Single Nucleotide; D011247:Pregnancy / Q000097:blood; D018167:Receptors, Calcitriol / Q000235:genetics*; D012885:Skinfold Thickness; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood; D014808:Vitamin D Deficiency / Q000097:blood / Q000235:genetics*; D044465:White People
D018167:Receptors, Calcitriol; D014807:Vitamin D; C104450:25-hydroxyvitamin D