The association between birth weight and adolescent systolic blood pressure in a caucasian birth cohort differs according to skin type, CRH promoter or 11HSD2 genotype

Terry Dwyer ^1*, Leigh Blizzard ², Briony Patterson ², Anne-Louise Ponsonby ¹, Kara Martin ², Stephen Quinn ², Michele M Sale ³, Stephen M Richards ², Ruth Morley ⁴, Stephen Rich ³ and Joanne L Dickinson ²

¹ Menzies Research Institute/Murdoch Childrens Research Institute, Australia
² Menzies Research Institute, Australia
³ Menzies Research Institute/University of Virginia School of Medicine, Australia
⁴ Murdoch Childrens Research Institute, Australia

^* To whom correspondence should be addressed. E-mail: terry.dwyer{at}mcri.edu.au.

Accepted 17 March 2008

Abstract

Objective: to examine twhether the inverse association between birth weight and blood pressure varies by skin pigmentation and/or related genotypes Study design: we followed-up 671 children from a predominantly Caucasian birth cohort to adolescence (mean age 14.4; SD 0.64).

Methods: Data on birthweight, socioeconomic status, maternal antenatal smoking, adolescent blood pressure and polymorphisms of candidate genes were obtained and analysed by multiple linear regression.

Results: an increase in birth weight of one kilogram was associated with a not statistically significant difference in adolescent systolic blood pressure of -0.53 mm Hg (95% CI -1.72 to 0.66mm Hg) per 1kg after adjustment for child age and cohort entry criteria. The inverse birth weight-systolic blood pressure association was stronger for those with darker skin ( 2% melanin) (P=0.02), for those with more copies of the C allele of corticotropin-releasing hormone (CRH) + T1273C (P=0.06), and for those with more copies of the short ( 236bp) form of the 11-HSD2 {CA} n repeat microsatellite (P=0.03).

Conclusions: These findings add to the evidence that cortisol-related pathways may account for at least part of the observed birth weight-blood pressure associations.