Cindy Boer

214 | Chapter 5.1 ▲ Figure 2: Characteristics of the final datasets of the two cohorts. GenR (A) and RS (B). Number of observed taxa at each taxonomy level Top: indicates the number of unique OTUs identified in each tax-onomic clade, top A: RS cohort, top B: GenR cohort. Bottom: Donut plots indicate the average relative abundances of the top major phyla in each cohort. Donut plots of the COPSAC cohort (children aged 6 years) and doughnut plots of FGFP and LLD cohorts (adults) are plotted for comparison with the abun-dance in GenR and RS. in the GenR cohort (mean 3.81; SD=0.57; Figure 2 ). Furthermore, we observed the absence of kingdom Archaea and a lower abundance of phylum Firmicutes in the GenR cohort as compared to RS ( Figure 2 ). To validate our datasets, we compared the averaged phylum level profiles of our cohorts with those of other cohorts of similar characteristics (i.e., age range, ethnic background). In addition, we tested the well-established association between BMI and alpha diversity[11,13,40], and we determined the association between single OTUs and BMI and compared these results with other cohorts. To compare GenR and RS 16S datasets with other populations, we used the 16S datasets of the COPSAC39, LLD[40,41] and FGFP[42] cohorts. The average phylum-level profiles of GenR were similar to those of COPSAC, and the average phylum-level pro- files of RS were similar to those of LLD and FGFP ( Figure 2 ). The lower abundance of phylum Firmicutes in the GenR cohort was also observed in the COPSAC cohort[39]. Further, in order to validate our microbiome datasets, we investigated the association of gut microbiome with BMI. We excluded subjects of non-Northern European origin from both GenR and RS, which resulted in a dataset of 1,712 GenR samples and a dataset of 1,371 RS samples.