The interplay of variants near LEKR and CCNL1 and social stress in relation to birth size.
BACKGROUND
We previously identified via a genome wide association study variants near LEKR and CCNL1 and in the ADCY5 genes lead to lower birthweight. Here, we study the impact of these variants and social stress during pregnancy, defined as social adversity and neighborhood disparity, on infant birth size. We aimed to determine whether the addition of genetic variance magnified the observed associations.


RESULTS
We analyzed data from the Northern Finland Birth Cohort 1986 (n=5369). Social adversity was defined by young maternal age (<20 years), low maternal education (<11 years), and/or single marital status. Neighborhood social disparity was assessed by discrepancy between neighborhoods relative to personal socio-economic status. These variables are indicative of social and socioeconomic stress, but also of biological risk. The adjusted multiple regression analysis showed smaller birth size in both infants of mothers who experienced social adversity (birthweight by -40.4 g, 95%CI -61.4, -19.5; birth length -0.14 cm, 95%CI -0.23, -0.05; head circumference -0.09 cm 95%CI -0.15, -0.02) and neighborhood disparity (birthweight -28.8 g, 95%CI -47.7, -10.0; birth length -0.12 cm, 95%CI -0.20, -0.05). The birthweight-lowering risk allele (SNP rs900400 near LEKR and CCNL1) magnified this association in an additive manner. However, likely due to sample size restriction, this association was not significant for the SNP rs9883204 in ADCY5. Birth size difference due to social stress was greater in the presence of birthweight-lowering alleles.


CONCLUSIONS
Social adversity, neighborhood disparity, and genetic variants have independent associations with infant birth size in the mutually adjusted analyses. If the newborn carried a risk allele rs900400 near LEKR/CCNL1, the impact of stress on birth size was stronger. These observations give support to the hypothesis that individuals with genetic or other biological risk are more vulnerable to environmental influences. Our study indicates the need for further research to understand the mechanisms by which genes impact individual vulnerability to environmental insults.
Department of Epidemiology and Biostatistics, Medical Research Council Health Protection Agency Centre for Environment and Health, Imperial College London, London, United Kingdom.
Anokhi
A
Ali Khan
Alina
A
Rodriguez
Sylvain
S
Sebert
Marika
M
Kaakinen
Stéphane
S
Cauchi
Philippe
P
Froguel
Anna-Liisa
AL
Hartikainen
Anneli
A
Pouta
Marjo-Riitta
MR
Järvelin
D000328:Adult; D000483:Alleles; D001724:Birth Weight / Q000235:genetics*; D015331:Cohort Studies; D016213:Cyclins / Q000235:genetics*; D005260:Female; D005387:Finland; D005838:Genotype; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D008423:Maternal Age; D015999:Multivariate Analysis; D020641:Polymorphism, Single Nucleotide; D011247:Pregnancy; D012044:Regression Analysis; D018570:Risk Assessment; D012307:Risk Factors; D012923:Social Class; D012959:Socioeconomic Factors; D013315:Stress, Psychological; D055815:Young Adult
C468873:CCNL1 protein, human; D016213:Cyclins