Description of growth curve fitting and derivation of growth parameters from the fitted curves is described in Text S1. The derived parameters from the Reed1 [32] and Jolicoeur-Pontier-Abidi-2 (JPA-2) [33] models were used separately as outcomes in the SNP association analysis. Due to skewness, natural logarithmic transformation was used for PHV1 and PHV2. To account for the random variation attached to the derived growth parameters, the association analyses were weighted by the number of measurements per person within the age period in question (infancy: 0–24 months, puberty: 8–16 years for girls, 9–17 years for boys). A regression model assuming an additive genetic effect was fitted between each SNP and each growth parameter, adjusted for sex and PCs. Additionally, the same analyses were run with sex-SNP interaction included. Preliminary analyses showed that adjusting additionally for birth length and gestational age does not essentially change the results, and this adjustment was not done. Results are reported per one allele increase in the genotype, the reference allele being the height decreasing allele in the previous GWA studies. SAS (version 9.1.3.) was used for all the association analyses of genetic variants and growth parameters.
