Nineteen SNPs that associated with adult height in Weedon et al, 2008 [4] or their proxies were genotyped using DNA collected as part of the NFBC1966 cohort at age 31 y. 5,470 DNA samples were available; maximum 4,577 were included in the final analyses due to the exclusions explained in the Statistical Analyses (see also Figure 2). Genotyping was conducted using TaqMan SNP genotyping assays (Applied Biosystems, Foster City, California). PCRs were carried as recommended in the assay literature and genotypes derived from a 7900HT Sequence Detection System plate reader (Applied Biosystems, Foster City, California). Twelve positive samples and twelve negative wells were used as part of the quality control protocol. Genotyping results were checked to ensure the allele frequencies were in HWE. A full plate (384) was duplicated for the purposes of quality control. The duplication error rate was calculated as the number of (genotypes disagreed/number of samples duplicated)/2. For most assays the duplication error rate was zero with no discrepancies between the results. There were four assays where one or two samples were discrepant between the two sets of genotyping (where approximately 340 samples were duplicated on both plates).
