Skip to main content
. Author manuscript; available in PMC: 2015 Jul 1.
Published in final edited form as: Behav Genet. 2014 May 3;44(4):368–382. doi: 10.1007/s10519-014-9656-8

Table 3. Variance of sIL-6R level due to rs2228145, total heritability of sIL-6R level, and estimates from linkage analysis.

Observed variance due to rs2228145 genotype
Genotype Frequencya sIL-6R level (10-8 g/mL)b Genotypic Value Frequency* sIL-6R (deviation from μ)2 Frequency*squared deviation
CC p2= 0.15 5.698 + a 0.15*5.698 = 0.87 (5.698- μ)2 = 2.32 0.15*2.32 = 0.35
AC 2pq=0.48 4.418 d 0.48*4.418 = 2.10 (4.418- μ)2 = 0.06 0.48*0.06 = 0.03
AA q2= 0.37 3.238 - a 0.37*3.238 = 1.20 (3.238- μ)2 = 0.88 0.37*0.88 = 0.33
Total μ=0.87+2.10+1.20 = 4.17 VSNP=0.35+0.03+0.33 = 0.71
(95% CI: 0.68-0.74)
Extended twin family model estimates
VsIL-6R VA VD VC VE V/Vtotal h2 d2 c2 e2
ACDE modelc Vtotal= 1.35 0.89 0.08 0.00 0.38 1.00 0.66 0.06 0.00 0.28
ACDE + rs2228145d Vresidual= 0.66 0.24 0.02 0.01 0.39 Vresidual/Vtotal= 0.49 0.18 0.01 0.01 0.29
Effect of rs2228145e VSNP= 0.69 0.65 0.06 -0.01 -0.01 VSNP/Vtotal= 0.51 0.48 0.05 0.01 0.01
Linkage analysis estimates
VsIL-6R VA-linkage VA-polygenic VD VC VE V/Vtotal h2 d2 c2 e2
Linkage modeled at rs2228145 Vtotal=1.39 0.96 0 - - 0.43 1 0.69 - - 0.31
Linkage+ association modeled at rs2228145 Vresidual=0.67 0.26 0 - - 0.41 Vresidual/Vtotal =0.48 0.19 - - 0.30
a

p=minor allele frequency=0.39 and q=major allele frequency=0.61

b

Mean sIL-6R level, corrected for age and sex, for each genotype group.

μ= Mean sIL-6R level in the population, estimated from the genotype frequencies and corresponding sIL-6R levels for each genotype group.

c

ACDE model without SNP effects, in which Vtotal is decomposed into VA, VD, VC, and VE.

d

Model in which the additive effect of rs2228145 on sIL-6R level is modeled, and the residual variance of sIL-6R (Vresidual=Vtotal - VSNP) is decomposed into VA, VC, VD and VE.

e

The effect of rs2228145 was inferred from the difference between model c and model d Vtotal=Total (phenotypic) variance of age- and sex-adjusted sIL-6R levels. VSNP= Variance of sIL-6R level attributable to rs2228145, VSNP/Vtotal = Proportion of total (phenotypic) variance sIL-6R level explained by rs2228145, Vresidual/Vtotal= Proportion of total (phenotypic) variance sIL-6R level not explained by rs2228145, VA=Additive genetic variance, VD=Non-additive genetic variance, VC=Sibling-shared environmental variance, VE=Unique environmental variance, h2= VA/Vtotal, d2= VD/Vtotal, c2= VC/Vtotal, e2= VE/Vtotal.

VA-linkage =Variance due to linkage, which is based on the pi-hat measure at rs2228145, derived from the IBD matrix of relatives

VA-polygenic = Variance due to all additive genetic effects that are not captured within the linkage component (i.e. additive genetic variance that is not linked to the IL6R locus), which was estimated from the phenotypic covariance of relatives following the assumption that on average 50% of VA-polygenic is shared among first degree relatives.