In addition, reliabilities of genomic prediction obtained by combining the reference populations of Danish, Swedish and Finnish red cattle were higher than those using single-country reference populations [ 8].
The masked SNPs were then imputed from the genotype information provided by the reference population.
Whilst absolute Z-scores may be influenced by the reference population, changes are more likely to be preserved.
For across-population genomic prediction, the genetic correlation between populations has to be taken into account, because it limits the part of the genetic variance in the selection candidates that can be explained by the reference population.
The differences in sensitivity and specificity rates may be explained by the reference population, adopted cut-offs from various references, methods used to assess %BF, and the cut-offs for excess fat [ 31, 33].
However, in agreement with most studies using other approaches and not adjusting by the reference population [ 5, 27- 32], our finding of lower emergency department utilisation by immigrants suggests overall lower healthcare use in this population.
The cutoff value for low FFM was defined as FFMI below the 10th percentile and obesity was defined as FMI above the 90th percentile, as defined by the reference population [ 40].
As shown in Table 2, general practitioners were most often contacted by both groups but were contacted significantly less often by ambulance personnel than by the reference population, both for men (62% vs. 54%, P <0.001) and women (80% vs. 65%, P <0.001).
Also, the use of an annual average of 3.7 medications in patients with FMS (significantly higher than the 1.4 medications used by the reference population) gives us an idea of the difficulty of treating this syndrome and the degree of inefficiency of the current therapeutic armaments available for this health care problem.
Therefore, the increase in accuracy of genomic prediction achieved by enlarging the reference population, as shown by e.g. [ 1- 3], might not only result from a more accurate prediction of SNP effects, but also from capturing a larger proportion of the alleles that segregate in the complete population.
